AIX 5.2b Security Target
Version: 1.10
Status: Final
Last Update: 2003-03-28
Document History
J.Haugh, A. Siegert
added P.STATIC to prevent dynamic
partitioning and TE.LPAR, OE.LPAR and
FDP_ACC.1 (LPAR), FDP_ACF.1 (LPAR) for
the IT environment to clearly express the
implications of the TOE running on LPAR
hardware; several minor adaptations
all
2003-03-28
1.10
Julie Haugh,
IBM Austin
Andreas Siegert, atsec
information security
Changes from AIX 5.2 to AIX 5.2b
All chapters
2003-02-27
1.0
Author
Summary
Changes
Date
Version
AIX 5.2b Security Target
Page 2 of 85 IBM Internal
© IBM 2002, 2003 2003.03.28
Table of Contents
25
5.2.6Selective Audit (FAU_SEL.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
5.2.5Selectable Audit Review (FAU_SAR.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
5.2.4Restricted Audit Review (FAU_SAR.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
5.2.3Audit Review (FAU_SAR.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
5.2.2User Identity Association (FAU_GEN.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
5.2.1Audit Data Generation (FAU_GEN.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
5.2Security Audit (FAU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
5.1.1 Requirements Taken from Protection Profile(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
5.1 TOE Security Functional Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
5 Security Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
4.2 Security Objectives for the TOE Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
4.1 Security Objectives for the TOE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
4 Security Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
3.4.3 Connectivity Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
3.4.2 Personnel Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
3.4.1 Physical Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
3.4 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17
3.3 Organizational Security Policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
3.2.2 Threats to be countered by measures within the TOE environment . . . . . . . . . . . . . .
16
3.2.1 Threats countered by the TOE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
3.2 Threats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
3 TOE Security Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
2.4.2.1 LPAR Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
2.4.2 Technical Environment for Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
2.4.1 File systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
2.4 Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
2.3 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
2.2.6 TSF Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
2.2.5 Security Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
2.2.4 Object Reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
2.2.3 Discretionary Access Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.2.2 Auditing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.2.1 Identification and Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
2.2 Summary of Security Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2.1 Intended Method of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
2 TOE Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
1.6 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.5 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.4 Strength of Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.3 CC Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.2 ST Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.1 ST Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AIX 5.2b Security Target
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44
6.3Detailed Design of Security Enforcing Functions . . . . . . . . . . . . . . . . . . . . . . . . . .
43
6.1.8 Secure and Non-Secure States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
43
6.1.7.2 Operation and Administrator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42
6.1.7.1 User Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42
6.1.7 TSF Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
42
6.1.6 TSF Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
41
6.1.5 Security Policy Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40
6.1.4 Network Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40
6.1.3 Non-Kernel TSF Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39
6.1.2 Kernel Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39
6.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39
6.1 Security Enforcing Components Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
39
6 TOE Summary Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
38
5.9 Security Requirements for the Non-IT Environment . . . . . . . . . . . . . . . . . . . . . . .
36
5.8 Security Requirements for the IT Environment . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
5.7.1 TOE Security Assurance Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
5.7 Strength of Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
5.6.4Reliable Time Stamps (FPT_STM.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
5.6.3Domain Separation (FPT_SEP.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
5.6.2Reference Mediation (FPT_RVM.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
5.6.1Abstract Machine Testing (FPT_AMT.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35
5.6Protection of the TOE Security Functions (FPT) . . . . . . . . . . . . . . . . . . . . . . . . . . .
34
5.5.9Security Management Roles (FMT_SMR.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34
5.5.9 Specification of Management Functions (FMT_SMF.1) . . . . . . . . . . . . . . . . . . . . . . . .
34
5.5.8Revocation of Object Attributes (FMT_REV.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
5.5.7Revocation of User Attributes (FMT_REV.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
5.5.6Management of Authentication Data (FMT_MTD.1) . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
5.5.5Management of User Attributes (FMT_MTD.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
5.5.4Management of Audited Events (FMT_MTD.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
5.5.3Management of the Audit Trail (FMT_MTD.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
5.5.2Static Attribute Initialization (FMT_MSA.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
5.5.1Management of Object Security Attributes (FMT_MSA.1) . . . . . . . . . . . . . . . . . . . . . .
32
5.5Security Management (FMT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
5.4.6User-Subject Binding (FIA_USB.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
5.4.5Identification (FIA_UID.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
5.4.4Protected Authentication Feedback (FIA_UAU.7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
5.4.3Authentication (FIA_UAU.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.4.2Strength of Authentication Data (FIA_SOS.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.4.1User Attribute Definition (FIA_ATD.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.4Identification and Authentication (FIA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.3.4Subject Residual Information Protection (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28
5.3.3Object Residual Information Protection (FDP_RIP.2) . . . . . . . . . . . . . . . . . . . . . . . . . .
26
5.3.2Discretionary Access Control Functions (FDP_ACF.1) . . . . . . . . . . . . . . . . . . . . . . . .
26
5.3.1Discretionary Access Control Policy (FDP_ACC.1) . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
5.3User Data Protection (FDP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
5.2.9Prevention of Audit Data Loss (FAU_STG.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25
5.2.8Action in Case of Possible Audit Data Loss (FAU_STG.3) . . . . . . . . . . . . . . . . . . . . . .
25
5.2.7Guarantees of Audit Data Availability (FAU_STG.1) . . . . . . . . . . . . . . . . . . . . . . . . . . .
AIX 5.2b Security Target
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© IBM 2002, 2003 2003.03.28
69
7.2 PP Tailoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
69
7.1 PP Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
69
7 Protection Profile Claims . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
68
6.5 TOE Security Functions requiring a Strength of Function . . . . . . . . . . . . . . . . . .
67
6.4 Assurance Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
67
6.3.2 User Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
6.3.1 System Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
6.3 Supporting functions not part of the TSF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
6.2.7.7 Diagnosis (TP.7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
66
6.2.7.6 Internal TOE Protection Mechanisms (TP.6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
65
6.2.7.5 TSF Databases (TP.5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64
6.2.7.4 Trusted Processes (TP.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64
6.2.7.3 Kernel Extensions (TP.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
64
6.2.7.2 Kernel (TP.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
6.2.7.1 TSF Invocation Guarantees (TP.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
6.2.7 TSF Protection (TP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
6.2.6.5 Time Management (SM.5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
62
6.2.6.4 Management of User, Group and Authentication Data (SM.4) . . . . . . . . . . . . . . . . . . .
61
6.2.6.3 Access Control Configuration and Management (SM.3) . . . . . . . . . . . . . . . . . . . . . . .
60
6.2.6.2 Audit Configuration and Management (SM.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60
6.2.6.1 Roles (SM.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60
6.2.6 Security Management (SM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
6.2.5.4 Object Reuse: Miscellaneous Objects (OR.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
6.2.5.3 Object Reuse: Queuing System Objects (OR.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
6.2.5.2 Object Reuse: IPC Objects (OR.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
58
6.2.5.1 Object Reuse: File System Objects (OR.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
57
6.2.5 Object Reuse (OR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
56
6.2.4.5 Discretionary Access Control: IPC Objects (DA.5) . . . . . . . . . . . . . . . . . . . . . . . . . . .
56
6.2.4.4 Discretionary Access Control: TCP Connections (DA.4) . . . . . . . . . . . . . . . . . . . . . . .
53
6.2.4.3 Discretionary Access Control: File System Objects (DA.3) . . . . . . . . . . . . . . . . . . . . .
53
6.2.4.2 Extended Permissions (DA.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
52
6.2.4.1 Permission Bits (DA.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
52
6.2.4 Discretionary Access Control (DA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
6.2.3.6 Audit Record Loss Prevention (AU.6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
6.2.3.5 Audit File Protection (AU.5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
50
6.2.3.4 Audit Review (AU.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
49
6.2.3.3 Audit Record Processing (AU.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
49
6.2.3.2 Audit Record Generation (AU.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
6.2.3.1 Audit Record Format (AU.1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
6.2.3 Auditing (AU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
6.2.2.6 Logoff Processing (IA.6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
6.2.2.5 Login Processing (IA.5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
6.2.2.4 User Identity Changing (IA.4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45
6.2.2.3 Interactive Login and Related Mechanisms (IA.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45
6.2.2.2 Common Authentication Mechanism (IA.2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
44
6.2.2.1 User Identification and Authentication Data Management (IA.1) . . . . . . . . . . . . . . . . .
44
6.3.2Identification and Authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
44
6.3.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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85
9 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
84
8.5 PP Claims Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
83
8.4.3 Strength of function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
83
8.4.2 Assurance Measures Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
8.4.1 Security Functions Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
8.4 TOE Summary Specification Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
8.3.9 Evaluation Assurance Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
8.3.8 Strength of function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
80
8.3.7 Justification of unresolved dependencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
8.3.6 Security Requirements Dependency Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
8.3.5 Security Requirements Sufficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
79
8.3.4 Justification of explicitly expressed security requirements . . . . . . . . . . . . . . . . . . . .
78
8.3.3 Rationale for Security Requirements for the IT environment . . . . . . . . . . . . . . . . . . .
77
8.3.2 Security Requirements Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
76
8.3.1 Security Requirements Refinements Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
75
8.3 Security Requirements Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
73
8.2.2 Security Objectives Sufficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
8.2.1 Security Objectives Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
8.2 Security Objectives Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
8.1.3 Rationale for additional Organizational Security Policies . . . . . . . . . . . . . . . . . . . . . .
72
8.1.2 Ratinale for the inclusion of Threats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71
8.1.1 Rationale for additonal Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71
8.1 Rationale for additional Threats, Assumptions and Organizational Security
Policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71
8 Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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References
[CC] Common Criteria for Information Technology Security Evaluation,
CCIMB-99-031, Version 2.1, August 1999
[CEM] Common Methodology for Information Technology Security Evaluation, CEM-99/045, Part 2 - Evaluation
Methodology, Version 1.0, 1999
[GUIDE] ISO/IEC PDTR 15446 Title: Information technology – Security techniques – Guide for the production of
protection profiles and security targets, ISO/IEC JTC 1/SC 27 N 2449, 2000-01-04
[CAPP] Controlled Access Protection Profile, Issue 1.d, 8 October 1999
[ITSEC] Information Technology Security Evaluation Criteria,
Version 1.2, CEC, June 1991
[ST-ITSEC] Security Target for AIX 4.3 (for the ITSEC evaluation)
[ST-BESTX] Security Target for the evaluation of BEST-X (Common Criteria Version 1.0)
[TARGET] AIX 5.2b Security Target (this document)
[CR] AIX Version 5.2b , Commands Reference Vols. 1-6
[BOS] AIX Version 5.2b, Technical Reference: Base Operating System and Extensions, Vols. 1-2
[COM] AIX Version 5.2b, Technical Reference: Communication
[KAS] AIX Version 5.2b, Technical Reference: Kernel and Subsystems, Vols 1-2
[FR] AIX Version 5.2b, Files Reference
[SMG] AIX Version 5.2b, System Management Guides
[SMC] AIX Version 5.2b, System Management Concepts
[NIMG] AIX Version 5.2b, Network Installation and Management Guide
[KEDS] AIX Version 5.2b, Kernel Extensions and Device Support Programming Concepts
[AIX6000] AIX Internals and Architecture, David A. Kelly, J. Ranade
Workstation Series, McGraw-Hill, 1996
[CIS] AIX Security Release 3.1, Component Interface Specification
[CDS] Administrative Command Security, Component Device Specification
[KERNEL] Kernel Internals, Workshop Documentation (AIX Worldwide Technology Transfer), Ken Rozendal
[CXREF] Cross Reference List of AIX 5.2b
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1 Introduction
This is the final version of the Security Target document for the evaluation of AIX 5.2b.
1.1 ST Identification
Title: AIX 5.2b Security Target, Version 1.1
Keywords: AIX, AIX 5.2b, general-purpose operating system, POSIX, UNIX, LPAR
This document is the security target for the CC evaluation of the IBM AIX 5L for POWER V5.2 with Recommended
Maintenance Package 5200-01, Program Number 5765-E62, (hereafter: AIX 5.2b) operating system product, and is
conformant to the Common Criteria for Information Technology Security Evaluation [CC].
1.2 ST Overview
This security target documents the security characteristics of the AIX 5.2b operating system.
AIX 5.2b is a highly-configurable UNIX-based operating system which has been developed to meet the requirements of
the Controlled Access Protection Profile developed by the Information Systems Security Organization within the
National Security Agency to map the TCSEC C2 class of the U.S. Department of Defence (DoD) Trusted Computer
System Evaluation Criteria (TCSEC) to the Common Criteria framework. This includes the requirements for
Identification and Authentication, Audit, Object Reuse and Access Control including the use of Access Control Lists.
Several servers running AIX 5.2b can be connected to form a distributed system. The communication aspects within
AIX 5.2b used for this connection are also part of the evaluation. It is assumed that the communication links themselves
are protected against interception and manipulation by measures which are outside the scope of this evaluation.
1.3 CC Conformance
This ST is conformant to the Controlled Access Protection Profile version 1.d [CAPP].
This ST is CC Part 2 extended and Part 3 conformant, with a claimed Evaluation Assurance Level of EAL4 augmented
by ALC_FLR.1.
Note: The evaluation assurance level named in the Protection Profile is EAL 3 with no augmentation. This Security
Target claims an evaluation assurance level of EAL 4 augmented by ALC_FLR.1. Since EAL 4 is hierarchical to EAL 3
conformance to the assurance requirements of the Protection Profile is given.
In addition this Security Target has replaced the security functional requirements FIA_UAU.1 and FIA_UID.1 as listed
in the Protection Profile by the security functional requirements FIA_UAU.2 and FIA_UID.2 which are hierarchical to
the ones listed in the Protection Profile. Compliance to the security functional requirements as listed in the Protection
Profile is therefore still given.
After the CAPP has been published and evaluated, AIS 32, Final Interpreation 065 of the CC has been published, which
defines a new family has been added to the FMT class. This family FMT_SMF has just one component FMT_SMF.1.
AIS 32, Final Interpretation 065 also has modified the definition of the components FMT_MOF.1, FMT_MSA.1 and
FMT_MTD.1 such that they now contain a dependency on the new component FMT_SMF.1. To comply with this
interpretation and satisfy the dependencies of FMT_MSA.1 and FMT_MTD.1, FMT_SMF.1 has been added as a
functional requirement. This then is additional to the requirements defined in the CAPP.
EAL 4 has been augmented by ALC_FLR.1 since this is also covered by the Mutual Recognition Arrangement.
1.4 Strength of Function
The claimed strength of function for this TOE is: SOF-medium.
1.5 Structure
The structure of this document is as defined by [CC] Part 1 Annex C.
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y Section 2 is the TOE Description.
y Section 3 provides the statement of TOE security environment.
y Section 4 provides the statement of security objectives.
y Section 5 provides the statement of IT security requirements.
y Section 6 provides the TOE summary specification, which includes the detailed specification of the IT Security
Functions.
y Section 7 provides the Protection Profile claim
y Section 8 provides the rationale for the security objectives, security requirements, TOE summary specification and
PP claims against [CAPP].
1.6 Terminology
This section contains definitions of technical terms that are used with a meaning specific to this document. Terms
defined in the [CC] are not reiterated here, unless stated otherwise.
Administrative User: This term refers to an administrator of an AIX system. Some administrative tasks requires use of
the root username and password so that they can become the superuser (with a user ID of 0) while other tasks can be
performed by specified users only.
Authentication data: This includes a user identifier, password and authorizations for each user of the product.
Object: In AIX, objects belong to one of four categories: file system objects, other kernel objects (such as processes,
programs and interprocess communication), window system objects and miscellaneous objects. See table xx in section
on object reuse for a list of all objects handled by AIX 5.2b.
Product: The term product is used to define all hardware and software components that comprise the distributed AIX
5.2b system.
Public object: A type of object for which all subjects have read access, but only the TSF or the system admibistrator
have write access.
Role: A role represents a set of actions that an authorized user, upon assuming the role, can perform.
Security Attributes: As defined by functional requirement FIA_ATD.1, the term ‘security attributes’ includes the
following as a minimum: user identifier; group memberships; user authentication data; and security-relevant roles.
Subject: There are two classes of subjects in AIX:
y untrusted internal subject - this is an AIX process running on behalf of some user, running outside of the TSF (for
example, with no privileges).
y trusted internal subject - this is an AIX process running as part of the TSF. Examples are service daemons and the
process implementing the identification and authentication of users.
System: Includes the hardware, software and firmware components of the AIX product which are connected/networked
together and configured to form a usable system.
Target of Evaluation (TOE): The TOE is defined as the AIX 5.2b operating system, running and tested on the hardware
and firmware specified in this Security Target. The BootPROM firmware as well as the hardware form part of the TOE
Environment.
User: Any individual/person who has a unique user identifier and who interacts with the AIX product.
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2 TOE Description
The target of evaluation (TOE) is the operating system AIX Version 5.2b.
AIX is a general purpose, multi-user, multi-tasking operating system. It is compliant with all major international
standards for UNIX systems, such as the POSIX standards, X/Open XPG 4, Spec 1170, and FIPS Pub 180. It provides a
platform for a variety of applications in the governmental and commercial environment. AIX is available on a broad
range of computer systems from IBM, ranging from departmental servers to multi-processor enterprise servers, and is
capable of running in an LPAR (Logical Partitioning) environment.
The AIX 5.2b evaluation shall consist of a distributed, closed network of high-end, mid-range and low-end IBM pSeries
servers running the evaluated version of AIX 5.2b. The hardware platforms selected for the evaluation shall consist of
machines which are projected to be available when the evaluation has completed and to remain available for a
substantial period of time afterwards.
The TOE Security Functions (TSF) consists of those parts of AIX that run in kernel mode plus some trusted processes.
This are the functions that enforce the security policy as defined in this Security Target. Tools and commands executed
in user mode that are used by the system administrator need also to be trusted to manage the system in a secure way. But
as with other operating system evaluations they are not considered to be part of this TSF.
Also the hardware and the BootProm firmware is considered not to be part of the TOE but part of the TOE environment.
The TOE shall include installation from CDROM and the network.
The TOE shall include standard networking applications, such as ftp, rlogin, rsh and NFS. Port-filtering will be used to
protect network applications which might otherwise have security exposures.
The TOE shall include the X-Window graphical interface and many X-Window applications. System administration
tools shall include the smitty non-graphical system management tool. The WebSM administrative tool is being excluded.
The TOE environment also includes applications that are not evaluated, but are used as unprivileged tools to access
public system services, for example the Netscape browser or the Adobe Acrobat Reader to access the supplied online
documentation (which is provided in HTML and PDF formats). No HTTP server is included in the evaluated
configuration.
2.1 Intended Method of Use
The TOE is a UNIX based multi-user multi-tasking operating system. The TOE is a multi-user system providing service
to several users at the same time. After successful login, the users have access to a general computing environment,
allowing the start-up of user applications, issuing user commands at shell level, creating and accessing files. The TOE
provides adequate mechanisms to separate the users and protect their data. Privileged commands are restricted to the
system administrator role.
Although AIX supports a concept of privileges, that allow to define several roles with specific administrative rights, this
Security Target does not include those privileges as part of the security requirements and security enforcing functions.
Instead the standard Unix model of unprivileged users and a system administrator with full root privileges is used. So,
whenever this Security Target mentions the system administrator role it is identical to a the term „root”.
The TOE permits one or more processors and attached peripheral and storage devices to be used by multiple users to
perform a variety of functions requiring controlled shared access to the data stored on the system. Such installations are
typical of personal, workgroup, or enterprise computing systems accessed by users local to, or with otherwise protected
access to, the computer systems.
The TOE provides facilities for on-line interaction with users. Networking is covered only to the extent to which the
TOE can be considered to be part of a centrally-managed system that meets a common set of security requirements.
It is assumed that responsibility for the safeguarding of the data protected by the TOE can be delegated to the TOE
users. All data is under the control of the TOE. The data is stored in named objects, and the TOE can associate with
each controlled object a description of the access rights to that object.
All individual users are assigned a unique user identifier. This user identifier supports individual accountability. The
TOE authenticates the claimed identity of the user before allowing the user to perform any further actions.
The TOE enforces controls such that access to data objects can only take place in accordance with the access restrictions
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placed on that object by its owner or other suitably authorized user.
Access rights (e.g. read, write, execute) can be assigned to data objects with respect to subjects (users). Once a subject is
granted access to an object, the content of that object may be freely used to influence other objects accessible to this
subject.
AIX 5.2b is the platform for a large amount of commercial and scientific applications.
AIX 5.2b complies with the following international standards:
y XPG4 Base 95 Profile (X/Open Portability Guide),
y XPG4 Commands and Utilities V2 (X/Open Portability Guide),
y ANSI/IEEE 1003.2:1992,
y ISO/IEC 9945-2 1993
y FIPS PUB 189 (Effective date April 3, 1995)
y SPEC 1170
AIX 5.2b has significant security extensions compared to standard UNIX systems:
y Access Control Lists,
y Integrity Protection,
y A Journaled File System,
y Integrated login framework.
AIX 5.2b provides easy to use interfaces for users and system administrators:
y SMIT for system and user administration,
2.2 Summary of Security Features
The primary security features of the product are:
y Identification and Authentication
y Audit
y Discretionary Access Control
y Object reuse functionality
y Security Management
y TSF Protection.
These primary security features are supported by domain separation and reference mediation, which ensure that the
features are always invoked and cannot be bypassed.
2.2.1 Identification and Authentication
AIX 5.2b provides identification and authentication based upon user passwords. The quality of the passwords used can
be enforced through configuration options controlled by AIX 5.2b. Other authentication methods (e. g. Kerberos
authentication) that are supported by AIX 5.2b in general are not part of the evaluated configuration. Especially
pluggable authentication modules that would allow e. g. to use a token based authentication process are not part of the
evaluated configuration. The default configuration for authentication is used, which uses passwords to authenticate
users.
2.2.2 Auditing
AIX 5.2b can collect extensive auditing information about security related actions taken or attempted by users, ensuring
that users are accountable for their actions.
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For each event record, the audit event logger prefixes an audit header to the event-specific information. This header
identifies the user and process for which this event is being audited, as well as the time of the event. The code that
detects the event supplies the event type and return code or status and optionally, additional event-specific information
(the event tail). Event-specific information consists of object names (for example, files refused access or tty used in
failed login attempts), subroutine parameters, and other modified information.
This audit trail can be analyzed to identify attempts to compromise security and determine the extent of the compromise.
2.2.3 Discretionary Access Control
Discretionary Access Control (DAC) restricts access to objects, such as files and is based on Access Control Lists
(ACLs) and the standard UNIX permissions for user, group and others. Access control mechanisms also protect IPC
objects from unauthorized access. In addition, AIX Supports ACLs on Sockets for TCP connections.
2.2.4 Object Reuse
All resources are protected from Object Reuse (scavenging) by one of three techniques: explicit initialization, explicit
clearing, or storage management. Three general techniques are used to meet this requirement:
y Explicit Initialization: The resource’s contents are explicitly and completely initialized to a known state before the
resource is made accessible to a subject after creation.
y Explicit Clearing: The resource's contents are explicitly cleared to a known state when the resource is returned for
re-use.
y Storage Management: The storage making up the resource is managed to ensure that uninitialized storage is never
accessible.
2.2.5 Security Management
The management of the security critical parameters of AIX 5.2b is performed by the system administrator. A set of
commands that require system administrator privileges are used for system management. Security parameters are stored
in specific files that are protected by the access control mechanisms of the TOE against unauthorized access by users
that are not the system administrator.
2.2.6 TSF Protection
While in operation, the kernel software and data are protected by the hardware memory protection mechanisms. The
memory and process management components of the kernel ensure a user process cannot access kernel storage or
storage belonging to other processes.
Non-kernel TSF software and data are protected by DAC and process isolation mechanisms. In the evaluated
configuration, the reserved user ID root, or other reserved IDs equivalent to root, own the directories and files that
define the TSF configuration. In general, files and directories containing internal TSF data (e.g., audit files, batch job
queues) are also protected from reading by DAC permissions.
The TOE and the hardware and firmware components are required to be physically protected from unauthorized access.
The system kernel mediates all access to the hardware mechanisms themselves, other than program visible CPU
instruction functions.
The system administrator has the ability to start a program that checks the hardware for correct operation.
2.3 Software
The Target of Evaluation is based on the following system software:
y IBM AIX 5L for POWER V5.2 with Recommended Maintenance Package 5200-01, Program Number 5765-E62
The TOE documentation is supplied on CD-ROM.
The following table contains a list of LPPs / File Sets that make up the TOE.
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Table 2-2: List of LPPs / File Sets
System management tools.
sysmgt
AIX supported devices
devices
AIX Base Operating System
bos
X Windows server, libraries and applications
X11
Netscape browser and other client applications
Netscape
Various libraries, commands and classes associated with Java.
Java
Formats PDF files for on-screen viewing in an X-Window display.
Adobe
Description
LPP Name
2.4 Configurations
The evaluated configurations are defined as follows:
y The CC Evaluated file set must be selected at install time
y If a windowing environment is to be used, the CDE file set must be selected at install time.
y The role based system administration features of AIX 5.2b are not included.
y AIX 5.2b supports the use of IPv4 and IPv6, only IPv4 is included.
y Only 64 bit architectures are included.
y Web Based Systems Management (WebSM) is not included.
y Both network (NIM, Network Install Manager) and CD installations are supported.
y The default configuration for identification and authentication only. Support for other authentication options e.g.
smartcard authentication, is not included in the evaluation configuration.
y If the system console is used, it must be connect directly to the workstation and afforded the same physical
protection as the workstation.
y Dynamic Partitioning (Dynamic LPAR, DLPAR) is not supported in the evaluated configuration, i.e. the dynamic
(de-) allocation of resources to a partition during operations is not allowed and must be prevented by organizational
means in the IT environment.
The TOE comprises one or more of the server machines (and optional peripherals) listed in section 2.4.2 running the
system software listed in table 2-2 (a server running the above listed software is referred to as a “TOE server” below).
If the product is configured with more than one TOE server, they are linked by LANs, which may be joined by
bridges/routers or by TOE workstations which act as routers/gateways.
No other systems may be connected to the network.
2.4.1 File systems
The following file system types are supported:
y the new AIX journaled filesystem, jfs2,
y the standard remote filesystem access protocol, nfs (V3);
y the High Sierra filesystem for CD-ROM drives, cdrfsisofs.
y The process file system, procfs (/proc) , provides access to the process image of each process on the machine as if
the process were a “file”. Process access decisions are enforced by DAC attributes inferred from the underlying
process’ DAC attributes.
2.4.2 Technical Environment for Use
The following assumptions about the technical environment the TOE is intended to be used in are made:
a) The TOE is running on the following, LPAR enabled hardware platforms:
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ƒ IBM pSeries Symmetric Multiprocessor (SMP) Systems using Power4 CPUs (p630, p650, p690)
b) The following peripherals can be run with the TOE preserving the security functionality:
ƒ all terminals and printers supported by the TOE
ƒ all storage devices and backup devices supported by the TOE (hard disks, CDROM drives,streamer drives,
floppy disk drives)1
ƒ all Ethernet and Token-Ring network adapters supported by the TOE
ƒ all printer devices supported by the TOE
c) Network connectors supported by the TOE (e.g. Ethernet, Token Ring, etc.) supporting TCP/IP services over the
TCP/IP protocol stack.
2.4.2.1 LPAR Environment
The logical partitioning capable pSeries eServers p630, p650 and p690 support a logical partitioned environment that
enables the pSeries systems to run multiple logical partitions concurrently. In a logical partition, an operating system
instance runs with dedicated resources: processors, memory, and I/O slots. These resources are statically assigned to the
logical partition. The total amount of assignable resources is limited by the physically installed resources in the system.
Because the implementation of logical partitioning is static, one has to shut down every operating system instance in all
logical partitions to change the resource assignment of running logical partitions.
From a functional point of view, applications on top of an operating system are running inside partitions in the same
way they run on a stand-alone pSeries machine. There are no issues when moving an application from a stand-alone
server to a partition. Operating system software needs to be modified in some areas to call Hypervisor functions instead
of native code. The design of partitioning-capable pSeries servers is such that one partition is isolated from software
running in the other partitions, including protection against natural software defects and even deliberate software
attempts to break the partition barriers.
The logical resources of the underlying hardware that can be assigned to a partition are:
• Processors
• Main memory regions
• I/O slots
The assignment of those resources to the individual logical partitions is stored in non-volatile RAM. This part of the
NVRAM is maintained by a “Service Processor” and can not be read or modified directly by the TOE running in a
logical partition. The assignment itself is performed by a System Administrator, who uses a “Hardware Management
Console” (HMC) to define those assignments. The HMC communicates with the service processor that accepts the
commands from the HMC and sets the values to define the logical partitions in the non-volatile RAM (NVRAM)
accordingly.
The functions of the underlying LPAR architecture need to be used by different parts of the TOE. The following figure
shows the parts of AIX that interact with the functions of the IT environment. Adaptations in AIX have been made to
enable the TOE to interact in an LPAR specifíc way with the VMM, virtual TTY console, RTAS and kernel debugger.
Please note that the support of static logical partitions does not introduce any additional security functionality for the
TOE - the separation between partitions and protection of the TOE from operating systems running in other logical
partitions on the same underlying machine is completely enforced by the underyling machine.
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1
The system distinguishes between storage and backup devices. Storage devices are hardware devices holding parts of the AIX file
system, such as hard disks and CD ROMs. Backup devices are devices used for archiving data like floppy disks and streamer
tapes that do not have a file system. Note that the distinction depends on the actual usage.
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3 TOE Security Environment
3.1 Introduction
The statement of TOE security environment describes the security aspects of the environment in which the TOE is
intended to be used and the manner in which it is expected to be employed.
To this end, the statement of TOE security environment identifies the list of assumptions made on the operational
environment (including physical and procedural measures) and the intended method of use of the for the product,
defines the threats that the product is designed to counter, and the organisational security policies with which the
product is designed to comply.
3.2 Threats
The assumed security threats are listed below.
The IT assets to be protected comprise the information stored, processed or transmitted by the TOE. The term
“information” is used here to refer to all data held within a server, including data in transit between workstations.
The TOE counters the general threat of unauthorized access to information, where “access” includes disclosure,
modification and destruction.
The threat agents can be categorized as either:
y unauthorized users of the TOE, i.e. individuals who have not been granted the right to access the system; or
y authorized users of the TOE, i.e. individuals who have been granted the right to access the system.
The threat agents are assumed to originate from a well managed user community in a non-hostile working environment,
and hence the product protects against threats of inadvertent or casual attempts to breach the system security. The TOE
is not intended to be applicable to circumstances in which protection is required against determined attempts by hostile
and well funded attackers to breach system security.
The threats listed below are grouped according to whether or not they are countered by the TOE. Those that are not
countered by the TOE are countered by environmental or external mechanisms.
3.2.1 Threats countered by the TOE
T.UAUSER An attacker (possibly, but not necessarily, an unauthorized user of the TOE) may impersonate
an authorized user of the TOE. This includes the threat of an authorized user A that tries to
impersonate as another authorized user without knowing the authentication information.
T.UAACCESS An authorized user of the TOE may access information resources without having permission
from the person who owns, or is responsible for, the information resource for the type of access.
T.UAACTION An undetected violation of the security policy may be caused as a result of an attacker (possibly,
but not necessarily, an unauthorized user of the TOE) attempting to perform actions that the
individual is not authorized to do.
3.2.2 Threats to be countered by measures within the TOE environment
The following threats apply in environments where specific threats to distributed systems need to be countered.
TE.HWMF A unprivileged user or the privileged system administrator is losing stored data due to hardware
malfunction.
TE.COR_FILE Security enforcing or relevant files of the TOE are manipulated or accidentally corrupted
without the system administrator being able to detect this.
TE.HW_SEP The underlying hardware functions of the hardware the TOE is running on does not provide
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sufficient capabilities to support the self-protection of the TSF from unauthorized programs.
TE.LPAR When running in a logical partition, software running in a different partition than the TOE is
able to access resources that are assigned to the TOE (i.e. resource that belong to the partition
the TOE is running in).
3.3 Organizational Security Policies
The TOE complies with the following organizational security policies:
P.AUTHORIZED_USERS Only those users who have been authorized to access the information within the system
may access the system.
P.NEED_TO_KNOW The right to access specific data objects is determined on the basis of:
a) the owner of the object; and
b) the identity of the subject attempting the access; and
c) the implicit and explicit access rights to the object granted to the subject by the object owner.
P.ACCOUNTABLE The users of the system shall be held accountable for their actions within the system.
P.STATIC Dynamic partitioning must not be used for the allocation and de-allocation of resources to the
TOE’s partition during operation of the TOE. Only “static” partitioning may be performed while
the TOE is in a non-operating phase.
3.4 Assumptions
This section indicates the minimum physical and procedural measures required to maintain security of the AIX 5.2b
product.
3.4.1 Physical Aspects
A.LOCATE The processing resources of the TOE will be located within controlled access facilities which
will prevent unauthorized physical access.
A.PROTECT The TOE hardware and software critical to security policy enforcement will be protected from
unauthorized physical modification.
3.4.2 Personnel Aspects
A.MANAGE It is assumed that there are one or more competent individuals who are assigned to manage the
TOE and the security of the information it contains.
A.NO_EVIL_ADMIN The system administrative personnel are not careless, willfully negligent, or hostile, and will
follow and abide by the instructions provided by the administrator documentation.
A.COOP Authorized users possess the necessary authorization to access at least some of the information
man-aged by the TOE and are expected to act in a cooperating manner in a benign environment.
A.UTRAIN Users are trained well enough to use the security functionality provided by the system
appropriately.
A.UTRUST Users are trusted to accomplish some task or group of tasks within a secure IT environment by
excercising complete control over their data.
3.4.3 Connectivity Aspects
A.NET_COMP All network components (like bridges and routers) are assumed to correctly pass data without
modification.
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A.PEER Any other systems with which the TOE communicates are assumed to be under the same
management control and operate under the same security policy constraints. There are no
security requirements which address the need to trust external systems or the communications
links to such systems.
A.CONNECT All connections to peripheral devices and all network connections reside within the controlled
access facilities. Internal communication paths to access points such as terminals or other
systems are assumed to be adequately protected.
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4 Security Objectives
4.1 Security Objectives for the TOE
O.AUTHORIZATION The TOE must ensure that only authorized users gain access to the TOE and its resources.
O.DISCRETIONARY_ACCESS The TSF must control accessed to resources based on identity of users. The TSF
must allow authorized users to specify which resources may be accessed by which users.
O.AUDITING The TSF must record the security relevant actions of users of the TOE. The TSF must present
this information to authorized administrators.
O.RESIDUAL_INFO The TOE must ensure that any information contained in a protected resource is not released
when the resource is recycled.
O.MANAGE The TSF must provide all the functions and facilities necessary to support the authorized
administrators that are responsible for the management of TOE security and must ensure that
only authorized administrators are able to access such functionality.
O.ENFORCEMENT The TSF must be designed and implemented in a manner which ensures that the organizational
policies are enforced in the target environment The TOE security policy is enforced in a manner
which ensures that the organisational policies are enforced in the target environment i.e. the
integrity of the TSF is protected.
4.2 Security Objectives for the TOE Environment
All security requirements listed in this section are targetted at the non-IT environment of the TOE.
OE.ADMIN Those responsible for the TOE are competent and trustworthy individuals, capable of managing
the TOE and the security of the information it contains.
OE.CREDEN Those responsible for the TOE must ensure that user authentication data is stored securely and
not disclosed to unauthorized individuals. In particular:
Procedures must be established to ensure that user passwords generated by an administrator
during user account creation or modification are distributed in a secure manner, as appropriate
for the clearance of the system.
The media on which authentication data is stored must not be physically removable from the
distributed system by unauthorized users.
Users must not disclose their passwords to other individuals.
OE.INSTALL Those responsible for the TOE must establish and implement procedures to ensure that the
hardware, software and firmware components that comprise the distributed system are
distributed, installed and configured in a secure manner. This includes the static configuration of
logical partitions of the LPAR feature of the TOE environment.
OE.PHYSICAL Those responsible for the TOE must ensure that those parts of the TOE critical to security policy
are protected from physical attack which might compromise IT security objectives.
OE.INFO_PROTECTThose responsible for the TOE must establish and implement procedures to ensure that
information is protected in an appropriate manner. In particular:
DAC protections on security critical files (such as audit trails and authentication databases) shall
always be set up correctly.
All network and peripheral cabling must be approved for the transmittal of the most sensitive
data held by the system. Such physical links are assumed to be adequately protected against
threats to the confidentiality and integrity of the data transmitted.
OE.MAINTENANCE Administrators of the TOE must ensure that the comprehensive diagnostics facilities provided
by the product are invoked at every scheduled preventative maintenance period.
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OE.RECOVER Those responsible for the TOE must ensure that procedures and/or mechanisms are provided to
assure that, after system failure or other discontinuity, recovery without a protection (i.e.,
security) compromise is obtained.
OE.SOFTWARE_IN Those responsible for the TOE shall ensure that the system shall be configured so that only an
administrator can introduce new trusted software into the system.
OE.SERIAL_LOGIN Those responsible for the TOE shall implement procedures to ensure that users clear the screen
before logging off where serial login devices (e.g.IBM 3151 terminals) are used.
The following security objective applies in environments where specific threats to distributed systems need to be
countered. (Either physical protection measures or cryptographic controls may be applied to achieve this objective, but
they are not part of the TOE defined in this Security Target.)
OE.PROTECT Those responsible for the TOE must ensure that procedures and/or mechanisms exist to ensure
that data transferred between workstations is secured from disclosure, interruption or tampering.
OE.HW_SEP The underlying hardware must provide separation mechanism that can be used by the TOE to
protect the TSF and TSF data from unauthorized access and modification.
The following security objective applies when the TOE is running on underlying machines that have more than one
logical partition configured:
OE.LPAR The underlying hardware must protect the resources assigned to the logical partition the TOE is
running in against access from software running in a different logical partition.
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5 Security Requirements
5.1 TOE Security Functional Requirements
5.1.1 Requirements Taken from Protection Profile(s)
The security functional requirements for the TOE are as defined in [CAPP] with all the operations performed to SFRs
that have been left to the security target author. Two SFRs (FIA_UAU.1 and FIA_UID.1) defined in the PP have been
substituted by hierarchical superior ones (FIA_UAU.2 and FIA_UID.2). In addition the security functional requirement
FMT_SMF.1 has been added in accordance with AIS 32, Final Interpretation 065.
The security functional requirements of the Protection Profile are listed together with the Application Notes and
Rationals given in the Protection Profile. For some security functional requirements a specific Application Note for AIX
has been added.
5.2 Security Audit (FAU)
5.2.1 Audit Data Generation (FAU_GEN.1)
The TSF shall be able to generate an audit record of the auditable events listed in column “Event” of Table
5-1 (Auditable Events). This includes all auditable events for the basic level of audit, except FIA_UID.1’s
user identity during failures.
The TSF shall record within each audit record at least the following information:
a) Date and time of the event, type of event, subject identity, and the outcome (success or failure) of the
event;
b) The additional information specified in the „Details” column of Table 5-1 (Auditable Events)
Application Note from the PP: For some situations it is possible that some events cannot be automatically generated.
This is usually due to the audit functions not being operational at the time these events occur. Such events need to be
documented in the Administrative Guidance, along with recommendation on how manual auditing should be established
to cover these events.
Rationale from the PP: This component supports O.AUDITING by specifying the detailed, security-relevant and data
that the audit mechanism must be capable of generating and recording. The “basic” level of auditing was selected as
best representing the “mainstream” of contemporary audit practices used in the target environments.
Table 5-1: Auditable Events
FILE_Open
Unsuccessful attempts to read information
from the audit records.
FAU_SAR.2
5.2.4
See below1
Reading of information from the audit
records.
FAU_SAR.1
5.2.3
None
FAU_GEN.2
5.2.2
start_up:
ACCT_Enable
shutdown:
ACCT_Disable
Start-up and shutdown of the audit
functions.
FAU_GEN.1
5.2.1
Details
(Event Names)
Event
Component
Section
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1
Object auditing can be used to define the events to be audited specifically for the audit files. This feature allows to define the whole
set of events that should be audited for those files. Object auditing allows to define all actions on the audit file that should
generate an audit record.
USER_Login
PASSWORD_Change
USER_SU
All use of the user identification
mechanism, including the identity provided
during successful attempts.
FIA_UID.1
5.4.5
None
FIA_UAU.7
5.4.4
USER_Login
PASSWORD_Change
USER_SU
All use of the authentication mechanism.
FIA_UAU.1
5.4.3
USER_Login
PASSWORD_Change
USER_SU
Rejection or acceptance by the TSF of any
tested secret.
FIA_SOS.1
5.4.2
None
FIA_ATD.1
5.4.1
None
Note 1
5.3.4
None
FDP_RIP.2
5.3.3
FILE_Mode
FILE_Owner
FILE_Chpriv
FILE_Facl
FILE_Fchmod
FILE_Fchown
FILE_Fchpriv
FILE_Link
FILE_Mknod
FILE_Open (for
create)
FILE_Rename
FILE_Truncate
FILE_Unlink
FS_Rmdir
FS_Mount
FS_Umount
MSG_Owner
MSG_Mode
MSG_Delete
MSG_Create
SEM_Owner
SEM_Create
SEM_Delete
SEM_Mode
SHM_Create
SHM_Delete
SHM_Owner
SHM_Mode
All requests to perform an operation on an
object covered by the SFP.
FDP_ACF.1
5.3.2
None
FDP_ACC.1
5.3.1
AUD_Lost_Recs
Actions taken due to the audit storage
failure.
FAU_STG.4
5.2.9
AUD_Lost_Recs
Actions taken due to exceeding of a
threshold.
FAU_STG.3
5.2.8
None
FAU_STG.2
5.2.7
AUD_Bin_Def,
AUD_Events,
AUD_Objects
All modifications to the audit configuration
that occur while the audit collection
functions are operating.
FAU_SEL.1
5.2.6
None
FAU_SAR.3
5.2.5
Details
(Event Names)
Event
Component
Section
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PROC_Adjtime
Changes to the time.
FPT_STM.1
5.6.4
None
FPT_SEP.1
5.6.3
None
FPT_RVM.1
5.6.2
Diagnostic Error Log
or object auditing
(see Application Note)
Execution of the tests of the underlying
machine and the results of the test.
FPT_AMT.1
5.6.1
PROC_Privilege
Every use of the rights of a role.
(Additional / Detailed)
FMT_SMR.1
5.5.9
USER_Change
Modifications to the group of users that are
part of a role.
FMT_SMR.1
5.5.9
FILE_Acl
All modifications to the values of TSF
data.
FMT_REV.1
5.5.8
USER_Change
All attempts to revoke security attributes.
FMT_REV.1
5.5.7
USER_Change
PASSWORD_Change
PASSWORD_Flags
All modifications to the values of TSF
data.
FMT_MTD.1
5.5.6
USER_Change
All modifications to the values of TSF
data.
FMT_MTD.1
5.5.5
PROC_Sysconfig
ACCT_Disable
ACCT_Enable
AUD_it
AUD_Bin_Def
All modifications to the values of TSF
data.
FMT_MTD.1
5.5.4
Object auditing
events for the TSF
files containing the
TSF data
All modifications to the values of TSF
data.
FMT_MTD.1
5.5.3
Object auditing
events defined for
/etc/security/user
Modifications of the default setting of
permissive or restrictive rules.
All modifications of the initial value of
security attributes.
FMT_MSA.3
5.5.2
PROC_Environ
PROC_Privilege
PROC_Execute
PROC_RealUID
PROC_AuditID
PROC_SetUserIDs
PROC_RealGID
PROC_SetGroups
All modifications of the values of security
attributes.
FMT_MSA.1
5.5.1
PROC_Execute
PROC_RealUID
PROC_AuditID
PROC_SetUserIDs
PROC_RealGID
PROC_SetGroups
PROC_Environ
Success and failure of binding user security
attributes to a subject (e.g. success and
failure to create a subject).
FIA_USB.1
5.4.6
Details
(Event Names)
Event
Component
Section
Application Note for AIX: The execution of tests of the underlying machine and the results of the test are not stored in
the normal audit trail but in a separate Diagnostic Error Log file. This file is protected by the Discretionary Access
Control such that only the System Administrator can access the file. When an installation requires to audit the use of the
audit command, object auditing can be used where the diag command file is the object and execution is the access
mode.
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5.2.2 User Identity Association (FAU_GEN.2)
The TSF shall be able to associate each auditable event with the identity of the user that caused the event.
FAU_GEN.2.1
Application Note from PP: There are some auditable events which may not be associated with a user, such as failed
login attempts. It is acceptable that such events do not include a user identity. In the case of failed login attempts it is
also acceptable not to record the attempted identity in cases where that attempted identity could be misdirected
authentication data; for example when the user may have been out of sync and typed a password in place of a user
identifier.
Rationale from PP: O.AUDITING calls for individual accountability (i.e., “TOE users”) whenever security-relevant
actions occur. This component requires every auditable event to be associated with an individual user.
Application Note for AIX: AIX stores the identity of the user in the header field “ah_ruid” and “ah_luid” of each audit
record. For a description of the difference between the “real user id” and the “login user id” see chapter 6.
5.2.3 Audit Review (FAU_SAR.1)
The TSF shall provide authorized administrators with the capability to read all audit information from the
audit records: FAU_SAR.1.1
The TSF shall provide the audit records in a manner suitable for the user to interpret the information. FAU_SAR.1.2
Application Note from PP: The minimum information which must be provided is the same that which is required to be
recorded in 5.2.1.
The intent of this requirement is that there exist a tool for administrator be able to access the audit trail in order to assess
it. Exactly what manner is provided is an implementation decision, but it needs to be done in a way which allows the
administrator to make effective use of the information presented. This requirement is closely tied to 5.2.5 and 5.2.6. It is
expected that a single tool will exist within the TSF which will satisfy all of these requirements.
Rationale from PP: This component supports the O.AUDITING and O.MANAGE objectives by providing the
administrator with the ability to assess the accountability information accumulated by the TOE.
Application Note for AIX: The access control to audit files within AIX is regulated by the discretionary access control
of AIX. It is the task of the administrator to ensure that the audit files as well as the audit configuration files are
protected appropriately. Tools are provided to the administrator to read and format the audit records. For a more detailed
description see chapter 6.
5.2.4 Restricted Audit Review (FAU_SAR.2)
The TSF shall prohibit all users read access to the audit records, except those users that have been granted
explicit read-access. FAU_SAR.2.1
Application Note from PP: By default, authorized administrators may be considered to have been granted read access to
the audit records. The TSF may provide a mechanism which allows other users to also read audit records.
Rationale from PP: This component supports the O.AUDITING objective by protecting the audit trail from
unauthorized access.
Application Note for AIX: This requirement is satisfied by the access control facility of AIX. It is the task of the
system administrator to manage the read access right to the audit files appropriately.
5.2.5 Selectable Audit Review (FAU_SAR.3)
The TSF shall provide the ability to perform searches of audit data based on the following attributes: FAU_SAR.3.1
a) User identity;
b) the following audit record fields:
- audit event
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- user’s login name
- event status
- time the record was written
- command name
- process ID
- ID of the parent process
- kernel thread ID
- name of the host that generated the audit event
Application Note from PP: The ST must state the additional attributes that audit selectivity may be based upon (e.g.,
object identity, type of event), if any.
Rationale from PP: This component supports both the O.AUDITING and O.MANAGE objectives, by providing a
means for the administrator to assess the accountability information associated with an individual user.
Application Note for AIX: AIX provides two commands for audit data processing: AUDITPR and AUDITSELECT.
Details are described in chapter 6.
5.2.6 Selective Audit (FAU_SEL.1)
The TSF shall be able to include or exclude auditable events from the set of audited events based on the
following attributes: FAU_SEL.1.1
a) User identity;
b) file name
c) event type
Application Note from PP: The ST must state the additional attributes that audit selectivity may be based upon (e.g.,
object identity, type of event), if any.
Rationale from PP: This component supports both the O.AUDITING and O.MANAGE objectives, by providing a
means for the administrator to assess the accountability information associated with an individual user.
Application Note for AIX: The main configuration data for the audit is stored in the file /etc/security/audit/config. This
file together with /etc/security/user allows the administrator to include or exclude auditable events based on the identity
of the user. In addition the audit configuration file /etc/security/audit/objects allows to include or exclude auditable
events based on the file name.
5.2.7 Guarantees of Audit Data Availability (FAU_STG.1)
The TSF shall protect the stored audit records from unauthorized deletion. FAU_STG.1.1
The TSF shall be able to prevent modifications to the audit records. FAU_STG.1.2
Application Note from PP: On many systems, in order to reduce the performance impact of audit generation, audit
records will be temporarily buffered in memory before they are written to disk. In these cases, it is likely that some of
these records will be lost if the operation of the TOE is interrupted by hardware or power failures. The developer needs
to document what the likely loss will be and show that it has been minimized.
Rationale from PP: This component supports the O.AUDITING objective by protecting the audit trail from tampering,
via deletion or modification of records in it. Further it ensures that it is as complete as possible.
Application Note from AIX: Protection of stored audit records from deletion and modifications is performed using the
discretionary access control mechanisms of AIX.
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5.2.8 Action in Case of Possible Audit Data Loss (FAU_STG.3)
The TSF shall generate an alarm to the authorized administrator if the audit trail exceeds a configurable
limit of free blocks on the file system that holds the audit trail. FAU_STG.3.1 / NOTE 3
Application Note: For this component, an “alarm” is to be interpreted as any clear indication to the administrator that the
pre-defined limit has been exceeded. The ST author must state the pre-defined limit that triggers generation of the alarm.
The limit can be stated as an absolute value, or as a value that represents a percentage of audit trail capacity (e.g., audit
trail 75% full). If the limit is adjustable by the authorized administrator, the ST should also incorporate an FMT
requirement to manage this function.
Rationale from PP: This component supports the O.AUDITING and O.MANAGE objectives by providing the
administrator with a warning that a pending failure due to the exhaustion of space available for audit information.
Application Note from AIX: AIX 5.2b has been modified to implement such a variable and have it configurable.
5.2.9 Prevention of Audit Data Loss (FAU_STG.4)
The TSF shall be able to prevent auditable events, except those taken by the authorized administrator, and
either stop the system in panic mode or count the number of audit records lost if the audit trail is full.
FAU_STG.4.1 / NOTE 5
Application Note from PP: The selection of “preventing” auditable actions if audit storage is exhausted is minimal
functionality; providing a range of configurable choices (e.g., ignoring auditable actions and/or changing to a degraded
mode) is allowable, as long as “preventing” is one of the choices. If configurable, then FMT_MOF.1 should be
incorporated into the ST.
Rationale from PP: This component supports the O.AUDITING and O.MANAGE objectives by providing the audit trail
is complete with respect to non-administrative users while providing administrators with the ability to recover from the
situation.
Application Note for AIX: In the case all audit bins are full, AIX 5.2b can be configured to stop execution (panic) or
count the number of audit records lost. Normal execution can only be resumed after space for the audit bin is available.
This has to be achieved by an authorized administrator, that starts the system in single-user mode and perform the
necessry actions to make disk space available for auditing.
5.3 User Data Protection (FDP)
5.3.1 Discretionary Access Control Policy (FDP_ACC.1)
The TSF shall enforce the Discretionary Access Control Policy on processes acting on the behalf of users as
subjects and file system objects (ordinary files, directories, device special files, UNIX Domain socket
special files, named pipes), IPC objects (message queues, semaphores, shared memory segments) and
TCP ports as objects and all operations among subjects and objects covered by the DAC policy. FDP_ACC.1.1
Application Note from PP: For most systems there is only one type of subject, usually called a process or task, which
needs to be specified in the ST.
Named objects are those objects which are used to share information among subjects acting on the behalf of different
users, and for which access to the object can be specified by a name or other identity. Any object that meets this
criterion but is not controlled by the DAC policy must be justified.
The list of operations covers all operations between the above two lists. It may consist of a sublist for each
subject-named object pair. Each operation needs to specify which type of access right is needed to perform the
operation; for example read access or write access.
Rationale from PP: This component supports the O.DISCRETIONARY_ACCESS objective by specifying the scope of
control for the DAC policy.
Application Note for AIX: See chapter 6 for details of the Discretionary Access Control capabilities for the different
types of subjects.
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5.3.2 Discretionary Access Control Functions (FDP_ACF.1)
The TSF shall enforce the Discretionary Access Control Policy to objects based on the following: FDP_ACF.1.1
a) The user identity and group membership(s) associated with a subject; and
b) The following access control attributes associated with an object:
File system objects:
permission bits and extended permission. (Permission bits are the standard UNIX
permission bits for user, group, world. Extended permissions can be used to grant or deny
access to the granularity of a single user or group using Access Control Entries).
Access rights for file system objects are:
- read
- write
- execute (ordinary files)
- search (directories)
IPC objects:
permission bits
Access rights for IPC objects are:
- read
- write
TCP ports:
Access control lists with entries of the following form:
y user@host
y user@subnet
y group@host
y group@subnet
The only access right is the right to set up a connection on the specified port
The TSF shall enforce the following rules to determine if an operation among controlled subjects and
controlled objects is allowed: FDP_ACF.1.2
File system objects:
A subject must have search permission for every element of the pathname and the
requested access for the object. A subject has a specific type access to an object if the type
of access is within the union of all permission rights (grant entries) defined in the access
control list of the object for the subject and is not within the logical union of all restrictions
(deny entries) defined in the access control list of the object for the subject. If no entry in
the extended permissions either allows or denies access, the access right defined in the
permission bits apply. In any other case access is denied.
IPC objects:
Access permissions are defined by permission bits of the IPC object. The process creating
the object defines the creator, owner and group based on the userid of the current process.
Access of a process to an IPC object is allowed, if
y the userid of the of the current process is equal to the userid of the IPC object creator
or owner and the „owner” permission bit for the requested type of access is set or
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y the group id of the current process is equal to the goup id of the IPC object and the
„group” permission bit for the requested type of access is set or
y The „world” permission bit for the requested type of access is set
TCP ports:
Setting up a connection from another system to a TCP port on a given system can be
regulated by access control lists. A connection can only be established to a TCP port if the
connection is coming from a user and a host where the ACL for the TCP port has entry
either of the form user@host, group@host, user@subnet or group@subnet matches the
userid or groupid and the host or subnet.
In addition ports with numbers larger than 1024 can be turned into privileged ports, i. e. a
local user that wants to start a server process listening on such a port must have root
privileges.
The TSF shall explicitly authorize access of subjects to objects based in the following additional rules:
File System Objects:
A process with a user ID of 0 is known as a root user process. These processes are generally
allowed all access permissions. But if a root user process requests execute permission for a
program (as a file system object), access is granted only if execute permission is granted to
at least one user..
TCP ports:
Services listed in the file /etc/security/services are exempt from ACL checks FDP_ACF.1.3
The TSF shall explicitly deny access of subjects to objects based on no additional rules. FDP_ACF.1.4
Application Note from PP: A CAPP conformant TOE is required to implement a DAC policy, but the rules which
govern the policy may vary between TOEs; those rules need to be specified in the ST. In completing the rule assignment
above, the resulting mechanism must be able to specify access rules which apply to at least any single user. This single
user may have a special status such as the owner of the object. The mechanism must also support specifying access to
the membership of at least any single group. Conformant implementations include self/group/public controls and access
control lists.
A DAC policy may cover rules on accessing public objects; i.e., objects which are readable to all authorized users, but
which can only be altered by the TSF or authorized administrators. Specification of these rules should be covered under
5.3.2.
A DAC policy may include exceptions to the basic policy for access by authorized administrators or other forms of
special authorization. These rules should be covered under 5.3.2.
The ST must list the attributes which are used by the DAC policy for access decisions. These attributes may include
permission bits, access control lists, and object ownership.
A single set of access control attributes may be associated with multiple objects, such as all objects stored on a single
floppy disk. The association may also be indirectly bound to the object, such as access control attributes being
associated with the name of the object rather than directly to the object itself.
Rationale from PP: This component supports the O.DISCRETIONARY_ACCESS objective by defining the rules which
will be enforced by the TSF.
Application Note for AIX: The Discretionary access control mechanism is explained in more detail in chapter 6. There
the details of the handling of discretionary access control for the different types of objects is explained.
5.3.3 Object Residual Information Protection (FDP_RIP.2)
The TSF shall ensure that any previous information content of a resource is made unavailable upon the
allocation of the resource to all objects. FDP_RIP.2
Application Note from PP: This requirement applies to all resources governed by or used by the TSF; it includes
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resources used to store data and attributes. It also includes the encrypted representation of information.
Clearing the information content of resources on deallocation from objects is sufficient to satisfy this requirement, if
unallocated resources will not accumulate new information until they are allocated again.
Rationale from PP: This component supports the O.RESIDUAL_INFO objective.
Application Note for AIX: Chapter 6 describes for each object type how object resuse is handled.
5.3.4 Subject Residual Information Protection (Note 1)
The TSF shall ensure that any previous information content of a resource is made unavailable upon the
allocation of the resource to all subjects.4
Application Note from PP: This requirement applies to all resources governed by or used by the TSF; it includes
resources used to store data and attributes. It also includes the encrypted representation of information.
Clearing the information content of resources on deallocation from subjects is sufficient to satisfy this requirement, if
unallocated resources will not accumulate new information until they are allocated again.
Rationale from PP: This component supports the O.RESIDUAL_INFO objective.
Application Note for AIX: Chapter 6 describes how residual information protection for processes is handled.
5.4 Identification and Authentication (FIA)
5.4.1 User Attribute Definition (FIA_ATD.1)
The TSF shall maintain the following list of security attributes belonging to individual users: FIA_ATD.1.1
a) User Identifier;
b) Group Memberships;
c) Authentication Data;
d) Security-relevant Roles; and
e) Audit Classes.
Application Note from PP: The specified attributes are those that are required by the TSF to enforce the DAC policy,
the generation of audit records, and proper identification and authentication of users. The user identity must be uniquely
associated with a single individual user.
Group membership may be expressed in a number of ways: a list per user specifying to which groups the user belongs, a
list per group which includes which users are members, or implicit association between certain user identities and
certain groups.
A TOE may have two forms of user and group identities, a text form and a numeric form. In these cases there must be
unique mapping between the representations.
Rationale from PP: This component supports the O.AUTHORIZATION and O.DISCRETIONARY_ACCESS
objectives by providing the TSF with the information about users needed to enforce the TSP.
Application Note for AIX: The only security relevant role defined within the TOE is the role of a system administrator.
This role is identified by the userid of zero. The system needs to be configured such that access to files for system
administration is restricted such that no user not having a userid of 0 can have access to those critical files.
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4
This requirement was added in the CAPP Protection Profile to address resources that are not directly allocated to
objects. Chapter 6 explains in detail how object resuse is handled for many kind of resources, also those that are not
objects defined in this Security Target.
5.4.2 Strength of Authentication Data (FIA_SOS.1)
The TSF shall provide a mechanism to verify that secrets meet the following:FIA_SOS.1
a) For each attempt to use the authentication mechanism, the probability that a random attempt will succeed
is less than one in 1,000,000;
b) For multiple attempts to use the authentication mechanism during a one minute period, the probability
that a random attempt during that minute will succeed is less than one in 100,000; and
c) Any feedback given during an attempt to use the authentication mechanism will not reduce the
probability below the above metrics.
Application Note from PP: The method of authentication is unspecified by the CAPP, but must be specified in a ST. The
method which is used must be shown to have low probability that authentication data can be forged or guessed. For
example, if a password mechanism is used a set of metrics needs to be specified and may include such things as
minimum length of the password, maximum lifetime of a password, and the subjecting passwords to dictionary attacks.
The strength of whatever mechanism implemented must be subjected to a strength of function analysis. (See 6.7.2)
Rationale from PP: This component supports the O.AUTHORIZATION objective by providing an authentication
mechanism with a reasonable degree of certainty that only authorized users may access the TOE.
Application Note for AIX: The TOE supports a number of configuration parameter that allow a system administrator
to define a specific password policy. With a well-defined password policy and a clear guideline for users how to select
passwords that are hard to guess the requirement can be satisfied. Additionally, the TOE supports the ability to restrict
the number of failed attempts. The claimed strength of function for this mechanism is: SOF-medium.
5.4.3 Authentication (FIA_UAU.2)
The TSF shall require each user to be successfully authenticated before allowing any other TSF-mediated
actions on behalf of that user. FIA_UAU.2.1
Application Note from PP: The ST must specify the actions which are allowed by an unauthenticated user. The allowed
actions should be limited to those things which aid an authorized of possible user in gaining access to the TOE.
This could include help facilities or the ability to send a message to authorized administrators.
Rationale from PP: This component supports the O.AUTHORIZATION objective by specifying what actions
unauthenticated users may perform.
Application Note for AIX: AIX does not allow any TSF mediated action of a user that is not authenticated. The
Controlled Access Protection Profile specifies FIA_UAU.1 which allows to define actions that a user may perform
before being authenticated. Since FIA_UAU.2 is hierarchical to FIA_UAU.1, conformance to the Protection Profile is
achieved.
5.4.4 Protected Authentication Feedback (FIA_UAU.7)
The TSF shall provide only obscured feedback to the user while the authentication is in progress. FIA_UAU.7
Application Note from PP: Obscured feedback implies the TSF does not produce a visible display of any authentication
data entered by a user, such as through a keyboard (e.g., echo the password on the terminal). It is acceptable that some
indication of progress be returned instead, such as a period returned for each character sent.
Some forms of input, such as card input based batch jobs, may contain human-readable user passwords. The
Administrator and User Guidance documentation for the product must explain the risks in placing passwords on such
input and must suggest procedures to mitigate that risk.
Rationale from PP: This component supports the O.AUTHORIZATION objective. Individual accountability cannot be
maintained if the individual’s authentication data, in any form, is compromised.
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5.4.5 Identification (FIA_UID.2)
The TSF shall require each user to identify itself before allowing any other TSF-mediated actions on behalf
of that user. FIA_UID.2.1
Application Note from PP: The ST must specify the actions which are allowed to an unidentified user. The allowed
actions should be limited to those things which aid an authorized user in gaining access to the TOE. This could include
help facilities or the ability to send messages to authorized administrators.
The method of identification is unspecified by this PP, but should be specified in a ST and it should specify how this
relates to user identifiers maintained by the TSF.
Rationale from PP: This component supports the O.AUTHORIZATION objective by specifying what actions
unidentified users may perform.
Application Note for AIX: AIX does not allow any TSF mediated action of a user that is not identified. The Controlled
Access Protection Profile specifies FIA_UID.1 which allows to define actions that a user may perform before being
identified. Since FIA_UID.2 is hierarchical to FIA_UID.1, conformance to the Protection Profile is achieved.
5.4.6 User-Subject Binding (FIA_USB.1)
The TSF shall associate the following user security attributes with subjects acting on the behalf of that user:
FIA_USB.1.1
a) The user identity which is associated with auditable events;
b) The user identity or identities which are used to enforce the Discretionary Access Control Policy;
c) The group membership or memberships used to enforce the Discretionary Access Control Policy;
d) Audit Classes.
The TSF shall enforce the following rules on the initial association of user security attributes with subjects
acting on the behalf of a user:
a) Upon successful identification and authentication, the real user identifier, the effective user
identifier and audit user identifier shall be those specified in the user entry for the user that has
authenticated successfully.
b) Upon successful identification and authentication, the real group identifier, and the effective group
identifier shall be those specified via the group membership attribute in the user entry.
The TSF shall enforce the following rules governing changes to the user security attributes associated with
subjects acting on the behalf of a user:
a) The effective userID of a user can be changed by the use of an executable with the setuid bit set. In
this case the program is executed with the effective userID of the program owner. Access rights are
then evaluated using the effective userID of the program owner. The login userID is not changed
with this process, so all audit records can be traced to the real user that executes the program.
b) The effective userID of a user can be changed by the su command. In this case the effective userID
of the user is changed to the user specified in the su command (provided authentication is
successful). The login userID remains unchanged, so all audit records can be traced to the real user
that executes the program.
c) The effective groupID of a user can be changed by the use of an executable with the setgid bit set.
In this case the program is executed with the effective groupID of the program owner. Access rights
are then evaluated using the effective groupID of the program owner. The login userID is not
changed with this process, so all audit records can be traced to the real user that executes the
program.
Application Note: The DAC policy and audit generation require that each subject acting on the behalf of users have a
user identity associated with the subject. This identity is normally the one used at the time of identification to the
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system.
The DAC policy enforced by the TSF may include provisions for making access decisions based on a user identity
which differs from the one used during identification.
The ST must state, in 5.4.6, how this alternate identity is associated with a subject and justify why the individual user
associated with this alternate identity is not compromised by the mechanism used to implement it.
Depending on the TSF’s implementation of group membership, the associations between a subject and groups may be
explicit at the time of identification or implicit in a relationship between user and group identifiers. The ST must specify
this association. Like user identification, an alternate group mechanism may exist, and parallel requirements apply.
Rationale: This component supports the O.DISCRETIONARY_ACCESS and O.AUDITING objectives by binding user
identities to subjects acting on their behalf.
5.5 Security Management (FMT)
5.5.1 Management of Object Security Attributes (FMT_MSA.1)
The TSF shall enforce the Discretionary Access Control Policy to restrict the ability to modify the access
control attributes associated with a named object to system administrators and the owner of the object. In
the case of TCP ports modification to access control lists is restricted to system administrators only.
FMT_MSA.1.1
Application Note from PP: The ST must state the components of the access rights that may be modified, and must state
any restrictions that may exist for a type of authorized user and the components of the access rights that the user is
allowed to modify.
The ability to modify access rights must be restricted in that a user having access rights to a named object does not have
the ability to modify those access rights unless granted the right to do so. This restriction may be explicit, based on the
object ownership, or based on a set of object hierarchy rules.
Rationale from PP: This component supports the O.DISCRETIONARY_ACCESS objective by providing the means by
which the security attributes of objects are managed by a site.
5.5.2 Static Attribute Initialization (FMT_MSA.3)
The TSF shall enforce the Discretionary Access Control Policy to provide restrictive default values for
security attributes that are used to enforce the Discretionary Access Control Policy. FMT_MSA.3.1
The TSF shall allow the administrators and the owner of the object to specify alternative initial values to
override the default values when an object or information is created. FMT_MSA.3.2
Application Note from PP: A CAPP-conformant TOE must provide protection by default for all objects at creation time.
This may be done through the enforcing of a restrictive default access control on newly created objects or by requiring
the user to explicitly specify the desired access controls on the object at its creation. In either case, there shall be no
window of vulnerability through which unauthorized access may be gained to newly created objects.
Rationale from PP: This component supports the O.DISCRETIONARY_ACCESS objective by requiring that objects
are properly protected starting from the instant that they are created.
5.5.3 Management of the Audit Trail (FMT_MTD.1)
The TSF shall restrict the ability to create, delete, and clear the audit trail to authorized administrators.
FMT_MTD.1.1
Application Note from PP: The selection of “create, delete, and clear” functions for audit trail management reflect
common management functions. These functions should be considered generic; any other audit administration functions
that are critical to the management of a particular audit mechanism implementation should be specified in the ST.
Rationale from PP: The component supports the O.AUDITING and O.MANAGE objectives by ensuring that the
accountability information is not compromised by destruction of the audit trail.
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5.5.4 Management of Audited Events (FMT_MTD.1)
The TSF shall restrict the ability to modify or observe the set of audited events to authorized administrators.
FMT_MTD.1.1
Application Note from PP: The set of audited events are the subset of auditable events which will be audited by the
TSF. The term set is used loosely here and refers to the total collection of possible ways to control which audit records
get generated; this could be by type of record, identity of user, identity of object, etc.
It is an important aspect of audit that users not be able to effect which of their actions are audited, and therefore must
not have control over or knowledge of the selection of an event for auditing.
Rationale from PP: This component supports the O.AUDITING and O.MANAGE objectives by providing the
administrator with the ability to control the degree to which accountability is generated.
5.5.5 Management of User Attributes (FMT_MTD.1)
The TSF shall restrict the ability to initialize and modify the user security attributes, other than authentication
data, to authorized administrators. FMT_MTD.1.1
Application Note from PP: This component only applies to security attributes which are used to maintain the TSP. Other
user attributes may be specified in the ST, but control of those attributes are not within the scope of the CAPP.
Rationale from PP: This component supports the O.MANAGE objective by providing the administrator with the means
to manage who are authorized users and what attributes are associated with each user.
5.5.6 Management of Authentication Data (FMT_MTD.1)
The TSF shall restrict the ability to initialize the authentication data to authorized administrators. FMT_MTD.1.1
The TSF shall restrict the ability to modify the authentication data to the following: FMT_MTD.1.1
a) authorized administrators; and
b) users authorized to modify their own authentication data
Application Note from PP: User authentication data refers to information that users must provide to authenticate
themselves to the TSF. Examples include passwords, personal identification numbers, and fingerprint profiles. User
authentication data does not include the users identity. The ST must specify the authentication mechanism that makes
use of the user authentication data to verify a user’s identity.
This component does not require that any user be authorized to modify their own authentication information; it only
states that it is permissible. It is not necessary that requests to modify authentication data require reauthentication of the
requester’s identity at the time of the request.
Rationale from PP: This component supports the O.AUTHORIZATION and O.MANAGE objectives by ensuring
integrity and confidentiality of authentication data.
5.5.7 Revocation of User Attributes (FMT_REV.1)
The TSF shall restrict the ability to revoke security attributes associated with the users within the TSC to
authorized administrators. FMT_REV.1.1
The TSF shall enforce the rules: FMT_REV.1.2
a) The immediate revocation of security-relevant authorizations; and
b) Revocations/modifications made by an administrator to security attributes of a user like the user
identifier, user name, user group(s), user password or user login shell shall be effective the next
time the user logs in.
Application Note from PP: Many security-relevant authorizations could have serious consequences if misused, so an
immediate revocation method must exist, although it need not be the usual method (e.g., The usual method may be
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editing the trusted users profile, but the change doesn’t take effect until the user logs off and logs back on. The method
for immediate revocation might be to edit the trusted users profile and “force” the trusted user to log off.). The
immediate method must be specified in the ST and in administrator guidance. In a distributed environment the developer
must provide a description of how the “immediate” aspect of this requirement is met.
Rationale from PP: This component supports the O.MANAGE objective by controlling access to data and functions
which are not generally available to all users.
Application Note for AIX: The immediate revocation method that can be used in AIX 5.2b is the one described in the
application note from the PP: Make the modifications to the users profile and then force the user to log off.
5.5.8 Revocation of Object Attributes (FMT_REV.1)
The TSF shall restrict the ability to revoke security attributes associated with objects within the TSC to users
authorized to modify the security attributes by the Discretionary Access Control policy.FMT_REV.1.1
The TSF shall enforce the rules: FMT_REV.
a) The access rights associated with an object shall be enforced when an access check is made; and
b) Access rights to file system and IPC objects are checked when the object is opened. Revocations of
access rights for file system objects become effective the next time a user affected by the revocation
tries to open a file system object.
Application Note from PP: The DAC policy may include immediate revocation (e.g., Multics immediately revokes
access to segments) or delayed revocation (e.g., most UNIX systems do not revoke access to already opened files). The
DAC access rights are considered to have been revoked when all subsequent access control decisions by the TSF use the
new access control information. It is not required that every operation on an object make an explicit access control
decision as long as a previous access control decision was made to permit that operation. It is sufficient that the
developer clearly documents in guidance documentation how revocation is enforced.
Rationale from PP: This component supports the O.DISCRETIONARY_ACCESS objective by providing that specified
access control attributes are enforced at some fixed point in time.
Application Note for AIX: Immediate revocation for file system objects is not implemented in AIX 5.2b. AIX 5.2b
uses delayed revocation as described in the application note from the PP. Immediate revocation is partly used within the
NFS file system, which is described below in the TOE summary specification.
5.5.9 Specification of Management Functions (FMT_SMF.1)
The TSF shall be capable of performing the following security management functions:
y Object security attributes management
y User attribute management
y Authentication data management
y Audit trail management
y Audit event management
Application Note: This security functional requirement has been added as a result of AIS 32, Final Interpretation 065.
This security functional requirement is not included in the CAPP, because the CAPP was developed before AIS 32,
Final Interpretation 065 was published. The security functional requirement was added because a dependency from
FMT_MSA.1 and FMT_MTD.1 to this new component has been defined in AIS 32, Final Interpretation 065.
5.5.10 Security Management Roles (FMT_SMR.1)
The TSF shall maintain the roles: FMT_SMR.1.1
a) authorized administrator;
b) users authorized by the Discretionary Access Control Policy to modify object security attributes;
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c) users authorized to modify their own authentication data; and
d) No other roles
The TSF shall be able to associate users with roles. FMT_SMR.1.2
Application Note from PP: A CAPP-conformant TOE only needs to support a single administrative role, referred to as
the authorized administrator. If a TOE implements multiple independent roles, the ST should refine the use of the term
authorized administrators to specify which roles fulfill which requirements.
The CAPP specifies a number of functions which are required of or restricted to an authorized administrator, but there
may be additional functions which are specific to the TOE. This would include any additional function which would
undermined the proper operation of the TSF. Examples of functions include: ability to access certain system resources
like tape drives or vector processors, ability to manipulate the printer queues, and ability to run real-time programs.
Rationale from PP: This component supports the O.MANAGE objective.
5.6 Protection of the TOE Security Functions (FPT)
5.6.1 Abstract Machine Testing (FPT_AMT.1)
The TSF shall run a suite of tests at the request of an authorized administrator to demonstrate the correct
operation of the security assumptions provided by the abstract machine that underlies the TSF. FPT_AMT.1.1
Application Note from PP: In general this component refers to the proper operation of the hardware platform on which a
TOE is running. The test suite needs to cover only aspects of the hardware on which the TSF relies to implement
required functions, including domain separation. If a failure of some aspect of the hardware would not result in the TSF
compromising the functions it performs, then testing of that aspect is not required.
Rationale from PP: This component supports the O.ENFORCEMENT objective by demonstrating that the underlying
mechanisms are working as expected.
Application Note for AIX: Such a test suite is provided as a separate program that an administrator may execute under
controlled conditions.
5.6.2 Reference Mediation (FPT_RVM.1)
The TSF shall ensure that the TSP enforcement functions are invoked and succeed before each function
within the TSC is allowed to proceed. FPT_RVM.1.1
Application Note from PP: This element does not imply that there must be a reference monitor. Rather this requires that
the TSF validates all actions between subjects and objects that require policy enforcement.
Rationale from PP: This component supports O.ENFORCEMENT objective by ensuring that the TSP is not being
bypassed.
5.6.3 Domain Separation (FPT_SEP.1)
The TSF shall maintain a security domain for its own execution that protects it from interference and
tampering by untrusted subjects. FPT_SEP.1.1
The TSF shall enforce separation between the security domains of subjects in the TSC. FPT_SEP.1.2
Application Note from PP: This component does not imply a particular implementation of a TOE. The implementation
needs to exhibit properties that the code and the data upon which TSF relies are not alterable in ways that would
compromise the TSF and that observation of TSF data would not result in failure of the TSF to perform its job. This
could be done either by hardware mechanisms or hardware architecture. Possible implementations include multi-state
CPU’s which support multiple task spaces and independent nodes within a distributed architecture.
The second element can also be met in a variety of ways also, including CPU support for separate address spaces,
separate hardware components, or entirely in software. The latter is likely in layered application such as a graphic user
interface system which maintains separate subjects.
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Rationale from PP: This component supports O.ENFORCEMENT objectives by ensuring that a TSF exists within the
TOE and that it can reliably carry out its functions.
5.6.4 Reliable Time Stamps (FPT_STM.1)
The TSF shall be able to provide reliable time stamps for its own use. FPT_STM.1.1
Application Note from PP: The generation of audit records depends on having a correct date and time. The ST needs to
specify the degree of accuracy that must be maintained in order to maintain useful information for audit records.
Rationale from PP: This component supports the O.AUDITING objective by ensuring that accountability information is
accurate.
Application Note for AIX: The reliability of the time stamp is provided by the monotonic increasing time within AIX
and the fact that all changes to the time are audited. This allows to terminate exactly the sequence of audit events (which
according to the application note within the PP is the source for this requirement). The accuracy of the internal clock is
on the level of nanoseconds, which allows a precise sorting of audit records according to the time they have been
generated.
5.7 Strength of Function
The claimed minimum strength of function is SOF-medium.
Note: The only security function within the TOE that uses a statiscal or probabilistic mechanism is the authentication
function that uses passwords.
5.7.1 TOE Security Assurance Requirements
The target evaluation assurance level for the product is EAL4 [CC] augmented by ALC_FLR.1.
5.8 Security Requirements for the IT Environment
The following requirements are stated on the underlying processor, that has to provide the mechanism to protect the
TSF and TSF data from unauthorizes access and tampering. This is expressed with the following security functional
requirement for the processor used to execute TOE software:
FDP_ACC.1 Subset access control
FDP_ACC.1.1 The TSF shall enforce the memory access control policy on instructions as
subjects and memory locations and processor register as objects.
FDP_ACF.1 Security attribute based access control
FDP_ACF.1.1 The TSF shall enforce the memory access control policy to objects based on the
processor state (user or supervisor).
FDP_ACF.1.2 The TSF shall enforce the following rules to determine if an operation among
controlled subjects and controlled objects is allowed: access to memory locations
and special registers is based on the processor state and the state of the
memory management unit. Access to dedicated processor registers is allowed
only if the processor is in supervisor state when the instruction accessing the
register is executed.
Application Note: The precise definition of the objects and the rules for the access control policy differ
slightly depending on the processor type. For this security requirement on the IT
environment the definition is detailed enough, since the implementation is not checked in
this evaluation. When used for the hardware evaluation of a real processor those rules have
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to be stated precisely.
FDP_ACF.1.3 The TSF shall explicitly authorise access of subjects to objects based on the
following additional rules: some dedicated processor registers may be read but
not modified when the instruction accessing the register is in user mode.
FDP_ACF.1.4 The TSF shall explicitly deny access of subjects to objects based on the following
rule: none.
FMT_MSA.3 Static attribute initialisation
FMT_MSA.3.1 The TSF shall enforce the memory access control policy to provide permissive
default values for security attributes that are used to enforce the SFP.
FMT_MSA.3.2 The TSF shall allow the no role to specify alternative initial values to override the
default values when an object or information is created.
Application Note: The „default” values in this case are seen as the values the processor has after start-up. They
have to be „permissive”, sine the initalization routine needs to set up the memory
management unit and the device register etc.. With respect to the hardware there is no
„role” model implemented but the access control policy is purely based on a single attribute
(„user” or „supervisor” state) that can not be managed or assigned to a „user”. The attribute
changes under well defines conditions (when the processor encounters an exception, an
interrupt or when the sc instruction is executed (which effectively causes an interrupt to
occur). The security requirement FMT_MSA.1 was therefore not applicable because the
security attribute can not be „managed”. For this reason there is also no security
requirement FMT_SMR.1 included, because there are no „roles” that need to be managed or
assigned to „users”. The dependency of FMT_MSA.3 to FMT_MSA.1 and FMT_SMR.1 is
therefore unresolved.
The following requirements target the operation of the TOE in an LPAR-enabled environment, where actually more
than one logical partition is configured on the underlying machine the TOE runs on:
FDP_ACC.1 (LPAR) Subset access control
FDP_ACC.1.1 The TSF shall enforce the LPAR resource access control policy on processores,
memory regions and I/O slots as objects and partitions as subjects and all
access to those resources by a partition.
FDP_ACF.1 (LPAR) Security attribute based access control
FDP_ACF.1.1 The TSF shall enforce the LPAR resource access control policy to objects based
on the partition number.
FDP_ACF.1.2 The TSF shall enforce the following rules to determine if an operation among
controlled subjects and controlled objects is allowed: a partition shall have access
to a processor, a memory region or an I/O slot only if the resource is allocated
to the partition by the table in the NVRAM.
FDP_ACF.1.3 The TSF shall explicitly authorise access of subjects to objects based on the
following additional rules: none.
FDP_ACF.1.4 The TSF shall explicitly deny access of subjects to objects based on the no other
rules.
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Note: OE.PROTECT mentions cryptographic controls as one possible security function to meet this objective. But it
also mentioned there that this objective can be fully met by physical protection features, which are then part of the
non-IT environment. Therefore it is not mandatory to address this security objective by a security function in the IT
environment.
5.9 Security Requirements for the Non-IT Environment
All the security objectives for the TOE environment address physical protection of the TOE or procedures that need to
be obeyed by system administrators.
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6 TOE Summary Specification
6.1 Security Enforcing Components Overview
6.1.1 Introduction
AIX 5.2b provides a multi-user, multitasking environment, where users interact with the operating system through
commands issued to a command interpreter. The command interpreter invokes command programs, which in turn
function by making system calls to the operating system kernel. The TSF is comprised of the kernel and trusted
processes (trusted programs that are not part of the kernel). All operations performed by users are mediated by the TSF
in accordance with the policies defined in Chapter 5.
Within AIX 5.2b a user can LOGIN to the console of any host computer, request local services at that computer, as well
as request network services from any other host in the system.
Processes perform all activity. A process may be started by a user issuing a command, may be created automatically to
service a network request, or may be part of the running system created at system initialization. Each process is running
a program. A process may begin running a new program (i.e., via the exec system call), or create a copy of itself (i.e.,
via the fork system call).
Some activities, such as responding to network requests, are performed directly by the kernel.
The following sections discuss services provided by the kernel, by non-kernel trusted software and the network services.
Network services are discussed separately because their implementation is split between kernel and non-kernel
components.
The description also contains some supporting functions or mechanism for the security functions. Those are later
marked with E_ followed by the name of the function or mechanism. The description of those functions and mechanism
then describes, if and how they contribute to satisfy the security functional requirements.
As long as those functions just provide a user interface (e. g. System Management tools) they are not considered to be
part of the TSF. But if they directly implement part of a security function (e. g. the trusted processes that reads
identification and authentication data) they are considered to be part of the TSF.
6.1.2 Kernel Services
The AIX kernel includes the base kernel and kernel extensions. The base kernel includes support for system
initialization, memory management, file and I/O management, process control, audit services and Inter-Process
Communications (IPC) services. Kernel extensions and device drivers are separate kernel software modules that
perform specific functions within the operating system.
Device drivers are implemented as kernel extensions.
The base kernel has the following key characteristics:
• Can be paged out: Portions of the kernel code and data can be paged out, permitting the kernel to run using less
memory than would be required for the whole kernel.
• Pinned: Part of the kernel is always resident or "pinned" into memory and cannot be paged. Pinned code cannot call
kernel services that may result in a page fault.
• Can be preempted: The AIX kernel can be preempted. Higher priority threads may interrupt kernel threads,
providing support for time critical functions.
• Dynamic and extendible: In standard AIX, kernel extensions can be loaded and unloaded while the system is
running to allow a dynamic, extendible kernel without requiring a rebuild and reboot. In the evaluated
configuration, dynamic changes to the kernel are prohibited through warnings described in the Security Guide. At
system start up, only the kernel extensions that are part of the evaluated product may be loaded. As an example, the
administrator can add pieces of hardware (as long as they are part of the hardware configuration listed in this
Security Target) to a specific configuration and reboot the system. This will cause the kernel extensions that support
the needed device drivers for the new hardware to be loaded. The ability to load/unload kernel extensions is
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restricted to the root identity.
The AIX kernel implements a virtual memory manager (VMM) that allocates a large, contiguous address space to each
process running on the system. This address space is spread across physical memory and paging space on a secondary
storage device. The VMM manages the paging space used by the AIX file system and provides memory buffers for use
within the kernel. The file system and VMM are tightly coupled. Disk pages, whether for file I/O or paging space, are
faulted into free pages in memory. The VMM does not maintain a separate pool of pages solely for file system I/O.
The process management component includes the software that is responsible for creating, scheduling, and terminating
processes and process threads. Process management allows multiple processes to exist simultaneously on a computer
and to share usage of the computer’s processor(s). A process is defined as a program in execution, that is, it consists of
the program and the execution state of the program.
Process management also provides services such as inter-process communications (IPC) and event notification. The
base kernel implements
• named pipes
• unnamed pipes
• signals
• semaphores
• shared memory
• message queues
• Internet domain sockets
• UNIX domain sockets
• Audit event generation
The file and I/O software provides access to files and devices. The AIX Logical File System (LFS) provides a consistent
view of multiple physical file system implementations. There are four different types of file systems included in the
evaluated configuration: Journaled File System 2 (JFS2), CDROM File System (CDRFS), Network File System (NFS)
and the Special File File System (SPECFS). JFS2 and CDRFS work off of a physical medium (disk, CDROM) and NFS
works across the network. SPECFS is a file system used internally by the kernel to support disk and other physical and
virtual device I/O. The process file system, PROCFS, provides access to the process image of each process on the
machine as if the process were a “file”. Process access decisions are enforced by DAC attributes inferred from the
underlying process’ DAC attributes.
6.1.3 Non-Kernel TSF Services
The non-kernel TSF services are:
• Identification and Authentication services
• Auditing journaling and post-processing services
• Network application layer services
Those services support the security functions implemented within the kernel and use the kernel interface for this
purpose, but they are not running themselves in kernel mode. Those functions are included in the TSF as far as they are
required for the security services of the TOE (Identification and Authentication services), while other services that are
implemented as tools or commands for the use of the system administrator and where the kernel prohibits the use misuse
of those tools or commands since they use kernel functions restricted to the system administrator and attempted use by
normal users is prohibited by the kernel.
6.1.4 Network Services
Each host computer in the system is capable of providing the following types of services:
• Local services to the user currently logged in to the local computer console.
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• Local services to previous users via deferred jobs.
• Local services to users who have accessed the local host via the network using protocols such as telnet.
• Network services to clients on either the local host or on remote hosts.
Network services are provided to clients via a client-server architecture. This client-server architecture refers to the
division of the software that provides a service into a client portion, which makes requests, and a server portion, which
carries out client requests (usually on a different computer). A service protocol acts as the interface between the client
and server.
The primary low-level protocols are Internet Protocol (IP), Transmission Control Protocol (TCP), and User Datagram
Protocol (UDP). IP is not user visible, but non-TSF processes may communicate with other hosts in the distributed
system using a reliable byte stream or unreliable datagrams, TCP and UDP respectively.
The higher-level network services are built on TCP or UDP. While the TOE supports the TCP application protocols
listed below, only the timed application protocol uses UDP and is provided by the TOE in the evaluated configuration.
The application protocols provided using TCP are:
• Internet remote login and file transfer services (telnet and ftp) are supported within the evaluated product, as are
similar BSD interfaces, including remote command execution (rlogin, rcp, rsh, rexec).
• The Hyper-Text Transfer Protocol (HTTP) is used by the WebInfo document display system (docsearch) for the
presentation of public data. The HTTP server is not security relevant and therefore not part of the TSF.
• The Network File System (NFS) protocol is supported for remote file access. This includes some subsidiary
protocols, such as the Remote Procedure Call (RPC), portmap protocols, and the mountd protocol for file system
import and export.
AIX 5.2b includes multiple X Windows clients in addition to an X Windows server on each host. Each server accepts
connections from local clients using UNIX domain sockets.
6.1.5 Security Policy Overview
Since the TOE is distributed across multiple host computers, each running a semiautonomous instance the AIX
operating system, the policy is described as follows:
• There is not a single kernel; rather, there is an AIX kernel running on each host computer in the system.
• The system does not have a common memory space; rather, each host in the system has its own memory space.
Memory management, segmentation and paging are all managed locally, without respect to other hosts.
• Identification and authentication (I&A) is performed locally by each host computer, but uses a common database.
Each user is required to LOGIN with a valid password and user identifier combination at the local workstation and
also at any remote computer where the user can enter commands to a shell program (e.g., remote login, and telnet
sessions).
• Neither the process ID, nor the associated thread IDs, are unique within the system; rather, a PID, and its associated
TIDs, are unique on each host within the system. Process and thread management is performed locally, without
respect to other hosts.
• The names of objects may not be unique within the system; rather, object names are unique on each host. For
example, each host maintains its own local file system, but may mount NFS exported file systems at various
locations in the local directory tree.
• Discretionary access control (DAC) is performed locally by each of the host computers and is based on user identity
and group membership. Each process has an identity (the user on whose behalf it is operating) and belongs to one
or more groups. All named objects have an owning user, an owning group and a DAC attribute, which is a set of
permission bits. In addition, file system objects optionally have an extended permission list also known as an
Access Control List (ACL). The extended permissions mechanism is a significant enhancement beyond traditional
UNIX systems, and permits control of access based on lists of users and/or groups to whom specific permissions
may be individually granted or denied. For TCP based services, an additional type of ACLs is provided that can be
used to restrict user access to specific services.
• Object reuse is performed locally, without respect to other hosts.
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• Audit is performed locally by each host computer. The audit facility generates audit records for activities performed
directly by untrusted processes (e.g., the system calls that perform file I/O) as well as trusted process activities (e.g.,
requests for batch jobs). Audit tools are available to merge audit files from the various hosts.
• Interrupt handling is performed locally, without respect to other hosts.
• Privilege is based on the root identity. All privileged processes (setuid root programs and programs run under the
root identity) start as processes with all privileges enabled. Unprivileged processes, which include setgid trusted
processes, start and end with no privileges enabled.
6.1.6 TSF Structure
The TSF is the portion of the system that is responsible for enforcing the system’s security policy. The TSF of AIX 5.2b
are distributed across each pSeries host computer and consists of three major components: kernel software, kernel
extension software, and trusted processes. All these components must operate correctly for the system to be trusted.
Those functions are supported by the mechanisms of the underlying hardware which are used to protect the TSF from
tampering by untrusted processes.
The AIX 5.2b Distributed System hardware components support two execution states where kernel mode or supervisor
state, software runs with hardware privilege and user mode or problem state software runs without hardware privilege.
AIX also provides two types of memory protection: segmentation and page protection. The memory protection features
isolate critical parts of the kernel from user processes and ensure that segments in use by one process are not available to
other processes. The two-state architecture and the memory protections form the basis of the argument for process
isolation and protection of the TSF.
The trusted processes include programs such as AIX administrative programs, scripts, shells, and standard UNIX
utilities that run with administrative privilege, as a consequence of being invoked by a user with the root identity.
Non-kernel TSF software also includes daemons that provide system services, such as networking and managing audit
data, as well as setuid and setgid programs that can be executed by untrusted users.
6.1.7 TSF Interfaces
Each sub-section here summarizes a class of interfaces in the AIX 5.2b Distributed System, and characterizes them in
terms of the TSF boundary. The TSF boundary includes some interfaces, such as commands implemented by privileged
processes, which are similar in style to other interfaces that are not part of the TSF boundary and thus not trusted. Some
interfaces are part of the TSF boundary only when used in a privileged environment, such as an administrator’s process,
but not when used in a non-privileged environment, such as a normal user process. All interface classes are described in
further detail in the next chapter, and the mechanisms in subsequent chapters. As this is only an introduction, no explicit
forward references are provided.
6.1.7.1 User Interfaces
The typical interface presented to a user is the command interpreter, or shell. The user types commands to the
interpreter, and in turn, the interpreter invokes programs. The programs execute hardware instructions and invoke the
kernel to perform services, such as file access or I/O to the user’s terminal. A program may also invoke other programs,
or request services using an IPC mechanism. Before using the command interpreter, a user must log in.
The command interpreter or shell as well as other programs operating on behalf of a user have the following interfaces:
• CPU instructions, which a process uses to perform computations within the processor's registers and a process's
memory areas. CPU instructions are interpreted by the hardware, which is part of the TOE environment; CPU
instructions are therefore not a TSF interface.
• System calls (e.g. open, fork), through which a process requests services from the kernel, and are invoked using a
special CPU instruction; System calls are the primary way for a program operating on behalf of a user to request
services of the TOE including the security services. System calls related to security functions are therefore part of
the TSF interface.
• Directly-invoked trusted processes (e.g. passwd) which perform higher-level services, and are invoked with an exec
system call that names an appropriate program which is part of the TSF, and replaces the current process's content
with it; a limited number of those processes exist that perform security functions and are therefore part of the TSF
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interface.
• Daemons, which accept requests stored in files or communicated via other IPC mechanisms, generally created
through use of directly invoked processes (some trusted, some untrusted). A few daemons peform security
functions and therefore present part of the TSF interface.
• Distributed Services, (e.g. telnet, NFS, rsh) The distributed services interface operates at many different levels of
abstraction. At the highest level, it provides a means for users on one host to request a virtual terminal connection
on another host within the system. At a lower level, it allows a host on the distributed system to request a specific
service from another host within the system on behalf of a user. Examples of requested services include, reading
data from a designated file (i.e. NFS), executing a command line (e.g. rsh) or transfering whole files (e.g. FTP). At
the lowest level, it allows a subject on one host in the system to request a connection (i.e. TCP), or deliver data (i.e.
UDP) to a listening subject. Distributed services usually consist of a client on the requestor’s side and a server
(usually a daemon) running on the server’s side. Authentication (if required by the service) and access control use
dedicated interfaces to the functions on the server side which are therefore part of the TSF interface.
6.1.7.2 Operation and Administrator Interface
The primary administrative interfaces to AIX 5.2b are the same as the interfaces for ordinary users; the administrator
logs into the system with a standard, untrusted, identity and password, and after assuming the root identity uses standard
AIX commands to perform administrative tasks.
The system is composed of one or more pSeries computer systems. Each of these host computers may be in one of the
following states: shut down, initialization, single-user mode, or multi-user secure state. Administration entails the
configuration of multiple computers and the interactions of those computers, as well as the administration of users,
groups, files, printers, and other resources within the system.
AIX 5.2b provides a general purposes, menu-based utility for system administration: smitty. Other programs (e.g.,
/usr/bin/acledit, /usr/bin/chuser, /usr/bin/rm) and scripts are used for system administration, but smitty is significant
because it provides comprehensive system administration capabilities.
smitty is required for the administration of the AIX 5.2b Distributed System, but the decision as to which administrative
utility to use depends upon whether or not the system is in a secure state:
• smitty (a cursor-based ASCII version of the System Management Interface Tool (SMIT)) is a graphical interface
and dispatcher for a collection of administrative programs.
smitty is used to administer the local host, i.e., the computer where it is run.
The system maintains an administrative database on a Network File System (NFS) server, referred to as the
administrative master server. The remaining hosts import the administrative data from the master server through
ordinary NFS client operations.
There are other tools for system administration (e. g. msmit) that provide a graphical user interface for system
administration. Those tools are not part of the evaluated configuration.
The part of the administrative database that is used to configure and manage TSF is seen as part of the TSF interface.
The administrative database is protected by the access control mechanisms of the TOE. It is therefore very important to
set the access rights to the files of the administartive database such that non-administrative users are prohibited from
modifying those files and have read access on a need to know basis only.
6.1.8 Secure and Non-Secure States
The secure state for the AIX 5.2b Distributed System is defined as a host’s entry into multi-user mode with auditing
fully operational, and with the administrative databases NFS-mounted from the master server. At this point, the host
accepts user logins and services network requests across the distributed system. If these facilities are not available, the
host is considered to be in a non-secure state. Although it may be operational in a limited sense and available for an
administrative user to perform system repair, maintenance, and diagnostic activity, the TSF are not in full operation and
is not necessarily protecting all system resources according to the security policy.
With respect to auditing this Security Target does not define a minimum level of events that need to be audited. But is is
required that the system administrator is able to configure all the events mentioned in this Security Target to be included
in the audit trail. A system administrator may then define - according to his requirements - define the events that are
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audited. He is able to change those events using the audit configuration functions during system operation.
6.2 Description of the Security Enforcing Functions
6.2.1 Introduction
This chapter describes how the Security Enforcing components of the TOE provide the Security Requirements
identified in chapter 5.
A high level description is provided for each group of Security Enforcing Functions providing a common feature or
service, and stating how the functionality specified by the Security Enforcing Function group is provided by the
Security Enforcing components identified in this Chapter.
The Security Enforcing Function groups identified in this chapter follow the description given in chapter 2:
y Identification and Authentication
y Audit
y Discretionary Access Control
y Object Reuse
y Security Management
y TOE Protection
The TOE Security Functions are described with sufficient detail to provide a general understanding of those functions
and how they work. A more detailed description of those functions and a mapping of the TSF to TOE subsystems is
provided in the high level design documentation.
References to components given in italics can be traced to manual pages or TOE sources for further information. Note
also that some commands initiate trusted processes or are a local front end to a trusted process (e.g. ftp and the ftpd
daemon, telnet and the telnetd daemon). In these instances, a generic reference to the command is made.
6.2.2 Identification and Authentication (IA)
User identification and authentication in the AIX 5.2b Distributed System includes all forms of interactive login (e.g.,
using the Telnet or FTP protocols) as well as identity changes through the su command. These all rely on explicit
authentication information provided interactively by a user.
Identification and authentication of users is performed either from a terminal where no user is logged on or when a user
that is logged on starts a service that requires additional authentication. All those services use a common mechanism for
authentication described as function IA.2 in this section. They all use the administrative database described in function
IA.1 in this section. The administrative database is managed by system administrators but users are allowed to modify
their own password using the passwd command. Function IA.3 describes the authentication process for those network
services that require authentication. Function IA.4 describes the change of the user’s identity using the su command.
Function IA.5 described the login process when a user logs in at a terminal. Function IA.6 describes the logoff process.
6.2.2.1 User Identification and Authentication Data Management (IA.1)
To ensure that the AIX 5.2b Distributed System is administered as a single entity, the system maintains a single
administrative database on a Network File System (NFS) server, referred to as the administrative master server. The
remaining hosts import the administrative data from the master server through ordinary NFS client operations.
The system maintains a consistent administrative database by making all administrative changes only on the designated
NFS server and exporting the database files to all the other computers in the system. A user ID on any computer refers
to the same individual on all other computers. In addition, the password configuration, name-to-UID mappings, and
other data are identical on all hosts in the distributed system.
Administrators, through the SMIT administrative interface, perform changes to the files that constitute the
administrative database.
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Users are allowed to change their passwords by using the passwd command, which is a setuid program with the owning
userid of 0. This configuration allows a process running the passwd program to read the contents of /etc/security/user
and to modify the /etc/security/passwd file for the user’s password entry, both which would ordinarily be inaccessible to
a non-privileged user process. Users are also forced to change their passwords at login time, if the password has
expired.
The file /etc/passwd conatins the user’s name, the id of the user, an indicator, if the password of the user is valid, the
principal group id of the user and a few other, not security relevant information. The encrypted password of the user
itself is not stored in this file but in the file /etc/security/passwd which can be protected against read access for ordinary
users. This prohibits dictionary attacks on passwords in the passwd file as for example described in the paper of Ken
Thomson and Bob Morris „Password Security - A Case History”.
The file /etc/security/passwd contains the encrypted password, the time the password was last changed and some other
information that are not subject to the security functions as defined in this Security Target.
For a complete list of user attributes see the description of the function SM.4.
The system administrator defines restrictions on authentication data like minimum and maximum size, the minimum
number of alphabetic characters, the minumum number of characters that are different from the old password, the
minimum number of non-alphabetic characters as well as the maximum life time of a password, the number of
unsuccessful login attempts allowed before the account is locked and the times and days the user is allowed to log into
the system. Those restrictions can be defined on a per user basis and are stored in the file /etc/security/user. The system
administrator can use those parameters to define a password policy such that the passwords satisfy the requirements
defined in FIA_SOS.1.
The file /etc/security/lastlog contains the time since the last successful login, the time of the last unsuccessful login and
the number of unsuccessful login attempts since the last successful login.
The mounting of the master happens during the AIX 5.2b Distributed System boot sequence, and the system is not in the
secure state until a successful mount of the administrative data occurs. If the mount fails, the system is inaccessible as it
hangs on the mount and will remain so until the administrator corrects the problem on the host causing the mount to fail.
Once the problem is resolved and the mount can occur successfully, the system will complete booting.
This function contributes to satisfy the security requirements FIA_ATD.1, FIA_SOS.1, FMT_MTD.1 „User Attributes”
and FMT_SMF.1.
6.2.2.2 Common Authentication Mechanism (IA.2)
AIX 5.2b includes a common authentication mechanism which is a subroutine used for all activities that create a user
session, including all the interactive login activities, batch jobs, and authentication for the SU command.
The common mechanism includes the following checks and operations:
• Check password authentication
• Check password expiration
• Check whether access should be denied due to too many consecutive authentication failures
• Get user security characteristics (e.g., user and groups)
The common I&A mechanism identifies the user based on the supplied user name, gets that user’s security attributes,
and performs authentication against the user’s password. A result of success indicated by a 1, or a failure indicated by a
0, is returned to the Terminal State Manager (TSM) program which continues the login process.
This function contributes to satisfy the security requirements FAU_GEN.2, FIA_UAU.2 and FIA_UID.2.
6.2.2.3 Interactive Login and Related Mechanisms (IA.3)
There are eight mechanisms for interactive login and similar activities:
• the standard login program (1) for interactive login sessions on the console of a user’s local host;
• the Telnet protocol (2) and the rlogin (3) protocol for ordinary interactive login sessions on any host in the system;
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• the rsh (4), RCP (5)and the rexec protocol (6) for remote shell, copy, and single command executions;
• the FTP protocol for interactive file transfer (7);
• and the su command for changing user identity during a session (8)
All of these mechanisms use the common authentication mechanism described above, but only those that create normal
interactive sessions use the standard login program; others implement special-purpose types of sessions.
All those mechanism will not display a password that is entered via a keyboard for authentication but provide obscured
feedback.
6.2.2.3.1 The Login Program
The login program establishes interactive user sessions. In AIX, login is part of the Terminal State Manager (TSM)
program. This program prompts for a user identity and authentication (i.e., password), and validates them using the
common authentication mechanism described above.
Authentication prompting may also be suppressed when appropriate (e.g., rsh ). If the validation fails, the prompts are
repeated until the limits on successive authentication failures are exceeded. Each failure is considered an event that may
be audited.
Login establishes a user session as follows:
1. Assigns a session identifier
2. Sets exclusive access for the controlling terminal to the process logging in
3. Calls the common authentication mechanism to check validity of the password provided for the account being
accessed, and gains the session security attributes
4. Sets up the user environment
5. Checks for password expiration and if so, prompts for password change
6. The process’s user and group identities are changed to those of the user
7. User is changed to his or her home directory
8. Invokes the user's default shell
The login program is always invoked with open file descriptors for the controlling terminal, used when prompting for
identity and authentication information, and passes control to the user's shell when the session is created. At this point,
the user session is established, the user environment is set up, and the program replaces itself, using the exec system
call, with the user’s shell).
6.2.2.3.2 Network Login
After an initial login on the console of any host in the distributed system, access to other hosts within the system may
occur through one of six network protocols: telnet, rlogin, rsh, rcp, rexec, and FTP.
6.2.2.3.2.1 Login with telnet
The telnet protocol always requests user identity and authentication by invoking the login program, which uses the
common authentication mechanism. A user can change identity across a telnet connection if the password for another
account is known.
6.2.2.3.2.2 Login with rlogin
The rlogin protocol includes user identity as part of the protocol information passed from host to host. User is not
permitted to switch identity between hosts using -l option. See the description of rsh command execution below for
details on the enforecement mechanism.
6.2.2.3.2.3 Command execution using rsh
The rsh protocol includes user identity as part of the protocol information passed from host to host. User is not
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permitted to switch identity between hosts using -l option. rshd checks to see that the remote and local user names are
the same. Remember that remote user ID information flows with the rsh connection request as part of the protocol. The
requirement that a privileged/reserved port be used as part of the setup insures that the information in the protocol flow
was created by a trusted process.
6.2.2.3.2.4 Command execution using rcp
The RCP protocol includes user identity as part of the protocol information passed from host to host. User is not
permitted to switch identity between hosts using -l option. See the description of command execution using rsh for
details of the enforcement mechanism.
6.2.2.3.2.5 Command execution using rexec
The rexec protocol always requires the user to enter a valid user identity and password. The authentication is performed
by invoking the common authentication mechanism directly rather than by invoking login. User can change identity if
password is known.
6.2.2.3.2.6 File transfer using FTP
The FTP protocol is used to create a special type of interactive session that only permits file transfer activities. An FTP
session is validated and created directly by the FTP server, which then executes all the user requests directly, as opposed
to invoking a user-specified program.
The FTP server invokes the authenticate() function that uses the common authentication mechanism to validate the user
identity and password supplied through FTP protocol transactions. User can change identity if password is known.
This function contributes to satisfy the security requirements FAU_GEN.2, FIA_UAU.2, FIA_UID.2 and FIA_UAU.7.
6.2.2.4 User Identity Changing (IA.4)
Users can change identity (i.e., switch to another identity) using the su command. When switching identities, the login
UID is not changed, so all actions are ultimately traceable in the audit trail to the originating user. The primary use of
the su command within the AIX 5.2b Distributed System is to allow appropriately authorized individuals the ability to
assume the root identity. In this system the capability to login as the root identity has been eliminated. In the
/etc/security/user file, login to root is set to false for all users and su is set to true for administrators. This allows an
administrative user to login under his/her real identity, then su to the root identity.
The su command invokes the common authentication mechanism to validate the supplied authentication.
This function contributes to satisfy the security requirement FAU_GEN.2 and FIA_USB.1.
6.2.2.5 Login Processing (IA.5)
Permissions on the device special files control access to exclusively used public devices. When a user successfully logs
in at the local attached terminal, the TSM program changes the ownership of /dev/lft0, /dev/kbd0, /dev/mouse0 and
/dev/rcm0 to the login UID of the user and sets the permissions on these devices to be readable and writable by this user.
/dev/lft0 is a logical device that provides the users interface to the keyboard, mouse, and graphics adapter. At system
initialization, /dev/lft0 grabs the keyboard, mouse and graphics adapter devices.
The /dev/kbd0 device contains two channels for communication between the keyboard and the device driver. Only one
channel is active at any given time. The /dev/lft0 device registers for the first channel when the system boots. The
second channel is reserved for the X server. The permissions on the /dev/kbd0 device restrict that only the user who is
logged in on the console can access this device. The logged in user could open the second channel, because he/she has
permissions. This would redirect the users own keyboard device. This would pose no threat to the operation of the
system. The worst thing that would happen is that the login process would not be able to regain access to the /dev/kbd0
device and no other users would be able to login on the console device until the host was rebooted.
The /dev/mouse0 device contains only one channel, which is grabbed by the /dev/lft0 device on system startup. Attempts
to open additional instances of the /dev/mouse0 device will result in an error message.
The login process executes a revoke to invalidate any open file descriptors for /dev/lft0 held by a previous user. The
revoke call modifies the file descriptors entry in the system open file table, causing further attempts to access the device
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special file based on that file descriptor to return “bad file descriptor”. This ensures that the new login session is isolated
from any previous login sessions.
This function contributes to satisfy the security requirement FIA_USB.1.
6.2.2.6 Logoff Processing (IA.6)
When a user logs off, all files that were opened by the login shell are closed. Files and devices that were opened by
background tasks remain open. However, a background job that had access to the console loses that access prior to the
next user’s login as stated above.
The ownership of /dev/lft0, /dev/kbd0, /dev/mouse0, and /dev/rcm0 is returned to root when the logoff occurs.
This function contributes to satisfy the security requirement FIA_USB.1.
6.2.3 Auditing (AU)
This section discusses the implementation of auditing in the evaluated configuration. The data structures and formats are
discussed first, followed by how audit is controlled, a description of bin mode auditing, the programs used to post
process the audit data, the programs used to review audit data, audit file protection, and finally the potential for audit
data loss.
Audit data is generated separately on each host in the distributed system and may be managed and analyzed either
separately on each host in the distributed system, or merged and analyzed on a single system. AIX includes tools for
pre-selecting and post-selecting audit data, viewing audit trails, and merging multiple audit trails into one file.
Function AU.1 discusses the format of the audit record. Here the data common to all audit records is explained.
Function AU.2 explains the system configuration files that control the audit feature of AIX.
6.2.3.1 Audit Record Format (AU.1)
The audit record consists of a header that contains information identifying the user and process who generated the
record, the status of the event (success or failure), and the CPU id for the system. The CPU id field allows the
administrator to differentiate between individual machines when merging the contents of multiple audit trails. An
optional variable length tail contains extra information about the event, as defined in /etc/security/audit/events.
The audit record is a fixed length record that contains information about the user who caused the event and whether the
event was created due to a success or failure. The audit record is defined in /usr/include/sys/audit.h.
The process ID of the process that wrote this record.
The program name of the process, along with a null terminator.
The login ID of the user who created the process that wrote this
record.
The real user ID; that is, the ID number of the user who created the
process that wrote this record.
An errno value describing the failure.
>1
Indicates a failure.
1
Indicates successful completion.
0
operation. The values for this field are:
An indication of whether the event describes a successful
The name of the event and a null terminator.
The length of the tail portion of the audit record.
Magic number for audit record.
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CPU identifier.
The nanoseconds offset from time. (used during bin recovery and trail
merging to ensure proper record ordering)
The time in seconds at which this audit record was written.
The thread ID.
The process ID of the parent of this process.
The above listed table shows that for each audit record the information required by FAU_GEN.1 and FAU_GEN.2 is
contained in the audit record.
6.2.3.2 Audit Record Generation (AU.2)
Audit record generation begins with the detection of an event, and follows the record as it advances to storage.
Event detection is distributed throughout the TSF, both in kernel and user mode. Programs and kernel modules that
detect events that may be audited are responsible for reporting these events to the system audit logger. The system audit
logger is part of the kernel, and can be accessed via a system call for trusted program auditing, or via a kernel procedure
call for supervisor state auditing.
The audit logger is responsible for constructing the complete audit record, including the identity and state information
and the event specific information. The audit logger appends the record to the active bin. A bin is a file that is used to
store raw audit records before they are processed and stored in the audit trail.
This function contributes to satisfy the security requirement FAU_GEN.1 and FAU_GEN.2.
6.2.3.3 Audit Record Processing (AU.3)
Audit record processing includes a description of bin mode auditing and the backend processors that are utilized by the
audit subsystem.
6.2.3.3.1 Bin Mode Auditing
When Bin mode auditing starts, two separate bin files are allocated to store raw audit records by the auditbin daemon.
When one bin file fills, the daemon switches to the other bin file and invokes the processing command specified in
/etc/security/audit/bincmds to empty the full cache file.
When that operation is complete, auditbin notifies the kernel that it is permitted to reuse the cache file. This mechanism
of switching and emptying audit bins continues so long as auditing is enabled. The size a bin file may reach before
being considered full is defined in /etc/security/audit/config.
A bin file begins with a header. The tail is written when the audit bin is switched or when auditing is shut down.
6.2.3.3.2 Backend Audit Processors
There are two backend processors available for use: auditcat and auditselect. The backend processor writes the raw
audit records to the system audit trail or to a specified file after manipulating them.
Bin mode auditing makes use of auditcat and auditselect. The result of auditcat or auditselect can be directed to a file
for permanent audit storage.
6.2.3.3.2.1 auditcat
The auditcat command reads audit records from standard input or from a file, and processes the records and sends them
to standard output or to the system audit trail.
6.2.3.3.2.2 auditselect
The auditselect command can be used as both a pre-processing and post-processing tool. As a pre-processing tool, the
auditselect command serves the same purpose as auditcat, but adds the ability to specify conditions that an audit record
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must meet. This allows a system to be configured to save audit records that relate to login in one file, and audit records
that relate to file access in a separate file.
Auditselect utilizes an expression to apply against the current audit record. The expression consists of one or more terms
joined by the logical operators && (and), || (or) and ! (not). Each term in the expression describes a field, a relational
operator and a value.
The following is an example expression to select all the FILE_Open events:
event==FILE_Open
The event field identifies that auditselect should query based on the name of the event. The operator is equal and the
name of the event is FILE_Open.
Table 6-2: Available Fields. The available fields are used to build expressions with auditselect.
Hostname of the machine that generated the record. The reserved name UNKNOWN can be
used to match any machines that are not listed in the /etc/security/audit/hosts file.
host
Date the audit event was generated.
date
Time of day the audit event was generated.
time
ID of the kernel thread that generated the event.
tid
ID of the parent of the process that generated the audit event.
ppid
ID of the process that generated the audit event.
pid
ID of the real user of the process that generated the audit event.
real
ID of the login user of the process that generated the audit event.
login
Status of the audit event. The value of the result field must be one of the following: OK,
FAIL, FAIL_PRIV, FAIL_AUTH, FAIL_ACCESS, or FAIL_DAC. FAIL matches all
other error codes.
command result
Name of the audit event
event
Definition
Field
Auditselect allows to selectively extract individual audit records as required by FAU_SAR.1 and FAU_SAR.3.
6.2.3.4 Audit Review (AU.4)
Two different commands exist for the review of audit records in the distributed system: auditpr and auditselect.
The auditpr command formats audit records to a display device or to a printer for review. The auditpr command also
allows the administrator to select which of the fields to include in the output as well as the order to display them. The
fields available for inclusion with the output of the auditpr command are listed in the following table.
Table 6-3. Available Fields From auditpr. These fields are are available for output from auditpr.
event
specific
tail data
name of
the host
that
generat
ed the
audit
record
kernel
thread
ID
ID of
the
parent
process
process
ID
real
user
name
comma
nd
name
time the
record
was
written
event
status
user’s
login
name
audit
event
The default values are the audit event, the user’s login name, the audit status, the kernel thread ID and the command
name auditselect allows the administrator to build an expression that will be applied to the stored audit records. The
details of the auditselect command are listed in section 6.2.3.4, Audit Record Processing.
The auditmerge command provides a method of combining multiple audit trail files into a single audit trail file. These
multiple files can come from different hosts in the system, providing a centralized audit analysis function. As the two
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files are processed, the record with the oldest time stamp that still remains is written into the audit trail. This process
continues until there are no more audit records to process. The Security Guide directs the system administrator to
transfer the audit files to be merged to the same host.
The commands auditpr and auditmerge allow an authorized administrator to read the audit records and convert them to
human readable format as required by FAU_SAR.1.
This function contributes to satisfy the security requirements FAU_SAR.1 and FAU_SAR.3.
6.2.3.5 Audit File Protection (AU.5)
The audit trail files, configuration files, bin files, and the /audit directory are protected on each system using normal file
system permissions. Each audit file grants read access to the root user and the audit group, and write access to only the
root user. The AIX 5.2b Security Guide instructs the administrator that if the cached and permanent audit trails are kept
other than in the /audit directory, then the alternate directory must be protected from access by non-root users.
This satisfies the requirements FAU_SAR.2, FAU_STG.1 and FMT_MTD.1 „Audit Trail”.
6.2.3.6 Audit Record Loss Prevention (AU.6)
Bin mode auditing is susceptible to the exhaustion of disk space available to the /audit directory or to a system crash. In
the case of a system crash, all data in physical memory is lost, including any audit records that had not yet been flushed
to disk. The audit subsystem enforces a 32K byte limit on the size of an individual audit record, and only one audit
record can be in transit between a thread and the kernel at any given time. When the system is no longer able to write
audit records to the audit bins either the system will stop in „panic” mode or a counter will show the number of audit
records lost. This counter is written in an audit record the next time the system is able to produce audit records again. If
the TOE stops in case it is unable to write audit records or if the TOE just counts the number of audit record lost is a
configuration parameter that can be set by the System Administrator.
The AIX 5.2b Security Guide includes instructions to the administrator to back up all files, including audit data, on a
regular basis to avoid the loss of data due to hard disk failures.
6.2.3.6.1 Audit Record Loss Prevention for Bin Mode Auditing
As a new feature of AIX 5.2b the system allows an administrator to define a threshold value for the amount of free
space in the file system holding the audit files. When the amount of free space in this file system is below this defined
threshold value this fact will be reported to an administrator. This allows the administrator to take the appropriate
actions to prevent the system to enter the panic mode due to the inability to write events to the audit trail.
AIX 5.2b provides a panic mode for use with bin mode auditing. The panic mode option halts the host when the current
audit bin stops accepting additional records, preventing the unnecessary loss of audit records. This only occurs with the
exhaustion of disk space. If a host halts because it cannot collect audit records, the other hosts in the distributed system
are not affected, unless the host is acting as the administrative master. The AIX 5.2b Security Guide contains
instructions for enabling panic mode, as panic mode is not enabled by default.
The result of halting the system because panic mode was invoked would be the loss of any audit data presently in the
host’s memory that had not been written to disk. In addition, audit records could be lost for operations that were
underway but had not yet completed generating audit records. This minimizes the damage caused by the lack of disk
space, because only the audit records that are currently in memory are lost.
A recovery process for audit bins exists in the evaluated configuration. If either of the bin files is not empty when audit
is started, the auditbin daemon executes the bin mode post-processing command to process the bins.
The amount of audit data that can be lost in bin mode is minimized by the use of the binsize and bytethreshold
parameters in the /etc/security/audit/config file. The binsize parameter sets the maximum size a bin may reach before the
auditbin daemon switches to the other bin, and executes the bin mode post-processing command. The bytethreshold
parameter sets the amount of data in bytes that is written to a bin before a synchronous update is performed. The AIX
5.2b Security Guide states that the binsize and bytethreshold parameters should be set to 64K bytes each to minimize
audit data loss. The amount of audit data that could be lost due to a failure in bin mode is the combination of these two
files, or 128K bytes.
This methods prohibits the loss of audit data as required by FAU_STG.3 and FAU_STG.4.
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6.2.4 Discretionary Access Control (DA)
This section outlines the general DAC policy in AIX 5.2b as implemented for resources where access is controlled by
permission bits and optionally, extended permissions; principally these are the objects in the file system. In all cases the
policy is based on user identity (and in some cases on group membership associated with the user identity). To allow for
enforcement of the DAC policy, all users must be identified and their identities authenticated.
Details of the specific DAC policy applied to each type of resource are covered in the section “Discretionary Access
Control: File System Objects” and the section “Discretionary Access Control: IPC Objects”.
The general policy enforced is that subjects (i.e., processes) are allowed only the accesses specified by the class-specific
policies. Further, the ability to propagate access permissions is limited to those subjects who have that permission, as
determined by the class-specific policies.
Finally, a subject with an effective UID of 0 is exempt from all restrictions and can perform any action desired.
DAC provides the mechanism that allows users to specify and control access to objects that they own. DAC attributes
are assigned to objects at creation time and remain in effect until the object is destroyed or the object attributes are
changed. DAC attributes exist for, and are particular to, each type of object on AIX 5.2b. DAC is implemented with
permission bits and, when specified, extended permissions.
A subject whose effective UID matches the file owner ID can change the file attributes, the base permissions, and the
extended permissions. Changes to the file group are restricted to the owner.
The new file group identifier must either be the current effective group identifier or one of the group identifiers in the
concurrent group set. In addition, a subject whose effective UID is 0 can make any desired changes to the file attributes,
the base permissions, the extended permissions, and owning user of the file.
Permission bits are the standard UNIX DAC mechanism and are used on all AIX 5.2b file system named objects.
Individual bits are used to indicate permission for read, write, and execute access for the object’s owner, the object’s
group, and all other users (i.e. world). The extended permission mechanism is supported only for file system objects and
provides a finer level of granularity than do permission bits.
6.2.4.1 Permission Bits (DA.1)
AIX 5.2b uses standard UNIX permission bits to provide one form of DAC for file system named objects. There are
three sets of three bits that define access for three categories of users: the owning user, users in the owning group, and
other users. The three bits in each set indicate the access permissions granted to each user category: one bit for read (r),
one for write (w) and one for execute (x). Each subject’s access to an object is defined by some combination of these
bits:
• rwx symbolizing read/write/execute
• r-x symbolizing read/execute
• r-- symbolizing read
• --- symbolizing null
When a process attempts to reference an object protected only by permission bits, the access is determined as follows:
• Effective UID = Object’s owning UID and the owning user permission bits allow the type of access requested.
Access is granted with no further checks.
• Effective GID, or any supplementary groups of the process = Object’s owning GID, and the owning group
permission bits allow the type of access requested. Access is granted with no further checks.
• If the process is neither the owner nor a member of an appropriate group and the permission bits for world allow the
type of access requested, then the subject is permitted access.
• If none of the conditions above are satisfied, and the process is not the root identity, then the access attempt is
denied.
This function contributes to satisfy the security requirements FDP_ACC.1 and FDP_ACF.1.
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6.2.4.2 Extended Permissions (DA.2)
The extended permissions consist of an essentially unlimited number of additional permissions and restrictions for
specific users and groups. Each entry in the extended permissions list consists of three parts: an entry type, a set of
permissions, and an identity list.
• The entry type is the value permit, deny, or specify (indicating that the entry indicates a set of permissions to be
allowed as supplemental to the listed identity(ies), denied to the listed identity(ies), or that the permissions
permitted and the complementary set denied to the listed identity(ies) respectively).
• The permission set is zero or more of the permissions read, write, and execute.
• The identity list is one or more values specifying users and/or groups. The entry is applied if the process’ effective
UID, effective GID, and supplemental groups match all values in the list. The term "match" means that for each
value in the identity list, if the value is for a UID, that the specified UID is the same as the process' effective UID,
and if the value is for a GID, that the specified GID is either the same as the process' effective GID or the specified
GID is included in the process’ list of supplemental GIDs.
There is no explicit ordering of entries within the extended permissions. To determine access rights, the kernel takes
into account all entries that match the UID or GID of the process. For each entry, the permit and specify bits are added
to a permissions list and the deny and bitwise negation of the specify are added to a restrictions list. The restrictions are
bitwise removed from the permissions and the resulting list is used in the access determination.
The maximum size for the extended permissions is one memory page (4096 bytes). The entries are variable length. Each
entry takes a minimum of 12 bytes (two for the length of the entry, two for the permission type and permissions
allowed, two for the number of identity entries, two for the type of identity entry, and four for each UID/GID). As a
result, there can be over 300 entries in an extended permissions list, which is in practice unlimited.
Collectively, the file attributes, base permissions, extended permissions, and extended attributes are known as the file
Access Control List (ACL). ACLs have a textual representation (used with commands such as ACLGET) and binary
representations (for storage in the file system). Table 7-2 is a textual representation of an ACL.
Together the Discretionary Access Control functions implement the requirements defined in FDP_ACC.1 and
FDP_ACF.1. Details of the Discretionary Access Control mechanism for individual object types are are described
below.
When a process attempts to reference an object protected by an ACL, it does so through a system call (e.g., open, exec).
If the object has been assigned an ACL access is determined as according to the algorithm below:
A subject must have search permission for every element of the pathname and the requested access for the object.
A subject has a specific type access to an object if the type of access is within the union of all permission rights
(grant entries) defined in the access control list of the object for the subject and is not within the logical union of
all restrictions (deny entries) defined in the access control list of the object for the subject. If no entry in the
extended permissions either allows or denies access, the access right defined in the permission bits apply. In any
other case access is denied.
This function contributes to satisfy the security requirement FDP_ACC.1 and FDP_ACF.1
6.2.4.3 Discretionary Access Control: File System Objects (DA.3)
The Discretionary Access Control (DAC) policy is described above. This section describes the details of DAC policies
as they apply to file system objects.
6.2.4.3.1 Common File System Access Control
This section describes the common DAC policy applied to file system objects, including policies for object contents and
attributes.
6.2.4.3.1.1 DAC Contents Policy
The permission-bit and ACL DAC policy determines the effective access that a process may have to the contents of a
file system object: some combination of read(r), write (w), and execute (x). In general, read access permits the object’s
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contents to be read by a process, and write permits them to be written; execute is interpreted differently for different
object types. Some object types (unnamed pipes, symbolic links) do not use the permission bits at all.
6.2.4.3.1.2 DAC Attributes Policy
In general, a process must be the object’s owner, or have privilege, to change the objects attributes, and there are no
DAC restrictions on viewing the attributes, so any process may view them. However, the following are exceptions to the
rule:
• The permission bits and ACL (permission bits, extended permissions and attributes) of an object may be changed
by an owner or by the root identity.
• The owning group ID of an object may be changed by an owner, but only to a group of which the process is
currently a member, unless it is the root identity.
• The owning user ID of an object may only be changed by the root identity.
6.2.4.3.1.3 DAC Defaults
The default access control on newly created FSOs is determined by the permissions associated with the directory where
the FSO was created, the effective user ID, group ID, and umask value of the process that created the FSO, and the
specific permissions requested by the program creating the FSO.
• The owning user of a newly created FSO will be the effective UID of the creating process.
• If the setgid bit is set on the containing directory, then the owning group of a newly created FSO will be the owning
group of the containing directory. If the setgid bit is not set on the containing directory, then the owning group of
the newly created FSO will be the effective GID of the creating process.
• The initial access permissions on the FSO are those specified by the creating process bit- wise ANDed with the
one’s complement of the umask value. For example, if a program specified initial permissions of 0664 (read/write
for owner, read/write for group, and read for world) but the umask value were set to 0027 (prevent write for group
or world, prevent all permissions for world), then the initial file permissions would be set to 0640 (or 0644 bit-and
0750).
• There are initially no extended permissions associated with an FSO. Extended permissions can be set by
applications or by users using AIX commands.
Base and extended access permissions can be changed by any process with an effective UID equal to the owning UID of
the FSO, providing that the effective UID has at least the execute permission to the containing directory. Note that since
a file may have multiple hard links, the process can use any of the containing directories (i.e., if there is any directory
containing a link to the file, then that path could be used as a means to get to the file and change its permissions).
6.2.4.3.1.4 DAC Revocation on File System Objects
With the exception of NFS objects, file system objects (FSOs) access checks are performed when the FSO is initially
opened, and are not checked on each subsequent access. Changes to access controls (i.e., revocation) are effective with
the next attempt to open the FSO.
For NFS objects, access is checked for each operation. A change to the access rights for an NFS FSO take effect as of
the next NFS request.
In cases where the administrator determines that immediate revocation of access to an FSO is required, the administrator
can reboot the computer, resulting in a close on the FSO and forcing an open of the FSO on system reboot. This method
is described in the AIX 5.2b Security Guide.
6.2.4.3.2 DAC: Ordinary File
In addition to read and write, ordinary files support the execute permission. Execute access is required to execute the
file as a program or script. When an executable file has the set-user-ID or set-group-ID flags set, and the file owner or
file group is not the same as the process’s current effective user-ID or group-ID the executing program changes the
process’s security attributes. Otherwise the attributes remain unchanged. One has to keep in mind that AIX doesn’t
support set-UID or set-GID scripts.
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6.2.4.3.3 DAC: Directory
The execute permission bit for directories governs the ability to name the directory as part of a pathname. A process
must have execute access in order to traverse the directory during pathname resolution.
Directories may not be written directly, but only by creating, renaming, and removing (unlinking) objects within them.
These operations are considered writes for the purpose of the DAC policy.
6.2.4.3.4 DAC: UNIX Domain Socket Special File
UNIX domain socket files are treated as files in the AIX file system from the perspective of access control, with the
exception that using the bind or connect system calls requires that the calling process must have both read and write
access to the socket file.
UNIX domain sockets exist in the file system name space, the socket files can have both base mode bits and extended
ACL entries.
UNIX domain sockets consist of a socket special file (managed by the File System) and a corresponding socket
structure (managed by IPC). The VFS controls access to the socket based upon the caller’s rights to the socket special
file.
6.2.4.3.5 DAC: Named Pipes
Named pipes are treated identically to any other file in the AIX file system from the perspective of access control.
Therefore permission bits and extended permissions can be used. For this reason named pipes are listed as file system
objects (although they are used for interprocess communication). Note that named pipes follow the rules for IPC
objects, if no extended permissions are used (which probably is the normal case they are used).
6.2.4.3.6 DAC: Device Special File
The access control scheme described for FSOs is used for protection of character and block device special files. Most
device special files are configured to allow read and write access by the root user, and read access by privileged groups.
With the exception of terminal and pseudo-terminal devices and a few special cases (e.g., /dev/null and /dev/tty),
devices are configured to be not accessible to normal users.
6.2.4.3.7 DAC: Special Cases for NFS File Systems
An NFS filesystem may contain any of the supported object types of the underlying filesystem. That includes device
special files. Non-regular files or directories which occur on NFS filesystems are treated similar to objects defined on
the local filesystem -- a device special file on an NFS mounted filesystem will reference the underlying device on the
local system. It would not reference the device on the remote system.
DAC checks by the NFS server for file contents permit a subject with the same effective owning user ID as the file to
have access to the contents regardless of the DAC attributes. This is used to support the standard UNIX semantics for
access to open files, because such access is not re-validated when a file’s DAC attributes change. This special case relies
on the property that, ordinarily, only a file’s owner changes its DAC while the file is open, and it is thus sufficient to
handle the owner specially.
DAC changes do have immediate effect for users other than the owner, unlike local files: if an NFS-accessed file’s DAC
is changed to deny access, any subsequent read or write operation to an open file will fail if the operation would no
longer be permitted by the new DAC attributes.
However, this can never grant additional access, because the client would have checked the access when the file was
opened and not permitted more access than the DAC attributes allowed at open time.
The filesystem maintains a “handle” on the credentials which were used at the time an NFS file was opened. It is those
credentials which are used to reference files via NFS, not the current process credentials which might be modified by
setuid().
This function contributes to satisfy the security requirement FDP_ACC.1, FDP_ACF.1, FMT_MSA.1, FMT_SMF.1,
FMT_MSA.3 and FPT_SEP.1.
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6.2.4.4 Discretionary Access Control: TCP Connections (DA.4)
TCP based services can be protected with ACLs as well.By specifying port,host/network,user combinations, ports can
be restricted to specific hosts and/or users. For example specifiying port 6000, machine colorado and user joe, only this
user coming from machine colorado will be able to connect to the X server. The remote hosts uses TCP AH headers to
end the information about the user together with the connection request. AIX 5.2b checks /etc/security/acl for permitted
clients.
With the DACinet Feature of AIX 5.2b the concept of privileged ports (ports that can only be opened by the superuser,
typically all ports below 1024) is extended so that any port now can be a privileged port. A bitmap of privileged ports is
defined to hold information on whether a port is privileged. A system administrator can modify this bitmap.
This function contributes to satisfy the security requirement FDP_ACC.1, FDP_ACF.1, FMT_MSA.1, FMT_SMF.1
and FMT_MSA.3.
6.2.4.5 Discretionary Access Control: IPC Objects (DA.5)
6.2.4.5.1 DAC: Shared Memory
For shared memory segment objects (henceforth SMSs), access checks are performed when the SMS is initially
attached, and are not checked on each subsequent access. Changes to access controls (i.e., revocation) are effective with
the next attempt to attach to the SMS.
In cases where the administrator determines that immediate revocation of access to a SMS is required, the administrator
can reboot the computer, thus destroying the SMS and all access to it.
This method is the described in the Security Guide. Since a SMS exists only within a single host in the distributed
system, rebooting the particular host where the SMS is present is sufficient to revoke all access to that SMS.
If a process requests deletion of a SMS, it is not deleted until the last process that is attached to the SMS detaches itself
(or equivalently, the last process attached to the SMS terminates).
However, once a SMS has been marked as deleted, additional processes cannot attach to the SMS and it cannot be
undeleted.
The default access control on newly created SMSs is determined by the effective user ID and group ID of the process
that created the SMS and the specific permissions requested by the process creating the SMS.
• The owning user and creating user of a newly created SMS will be the effective UID of the creating process.
• The owning group and creating group of a newly created SMS will be the effective GID of the creating process.
• The creating process must specify the initial access permissions on the SMS, or they are set to null and the object is
inaccessible until the owner sets them.
• SMSs do not have extended permissions.
Access permissions can be changed by any process with an effective UID equal to the owning UID or creating UID of
the SMS. Access permissions can also be changed by any process with an effective UID of 0, also known as running
with the root identity.
6.2.4.5.2 DAC: Message Queues
For message queues, access checks are performed for each access request (e.g., to send or receive a message in the
queue). Changes to access controls (i.e., revocation) are effective upon the next request for access. That is, the change
affects all future send and receive operations, except if a process has already made a request for the message queue and
is waiting for its availability (e.g., a process is waiting to receive a message), in which case the access change is not
effective for that process until the next request.
If a process requests deletion of a message queue, it is not deleted until the last process that is waiting for the message
queue receives its message (or equivalently, the last process waiting for a message in the queue terminates). However,
once a message queue has been marked as deleted, additional processes cannot perform messaging operations and it
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cannot be undeleted.
The default access control on newly created message queues is determined by the effective user ID and group ID of the
process that created the message queue and the specific permissions requested by the process creating the message
queue.
y The owning user and creating user of a newly created message queue will be the effective UID of the creating
process.
y The owning group and creating group of a newly created message queue will be the effective GID of the creating
process.
y The initial access permissions on the message queue must be specified by the creating process, or they are set to
null and the object is inaccessible until the owner sets them.
y Message queues do not have extended permissions.
Access permissions can be changed by any process with an effective UID equal to the owning UID or creating UID of
the message queue. Access permissions can also be changed by any process with an effective UID of 0.
6.2.4.5.3 DAC: Semaphores
For semaphores, access checks are performed for each access request (e.g., to lock or unlock the semaphore). Changes
to access controls (i.e., revocation) are effective upon the next request for access. That is, the change affects all future
semaphore operations, except if a process has already made a request for the semaphore and is waiting for its
availability, in which case the access change is not effective for that process until the next request.
In cases where the administrator determines that immediate revocation of access to a semaphore is required, the
administrator can reboot the computer, thus destroying the semaphore and any processes waiting for it. This method is
the described in the Security Guide. Since a semaphore exists only within a single host in the distributed system,
rebooting the particular host where the semaphores is present is sufficient to revoke all access to that semaphore.
If a process requests deletion of a semaphore, it is not deleted until the last process that is waiting for the semaphore
obtains its lock (or equivalently, the last process waiting for the semaphore terminates). However, once a semaphore has
been marked as deleted, additional processes cannot perform semaphore operations and it cannot be undeleted.
The default access control on newly created semaphores is determined by the effective user ID and group ID of the
process that created the semaphore and the specific permissions requested by the process creating the semaphore.
• The owning user and creating user of a newly created semaphore will be the effective UID of the creating process.
• The owning group and creating group of a newly created semaphore will be the effective GID of the creating
process.
• The initial access permissions on the semaphore must be specified by the creating process, or they are set to null
and the object is inaccessible until the owner sets them.
• Semaphores do not have extended permissions.
Access permissions can be changed by any process with an effective UID equal to the owning UID or creating UID of
the semaphore. Access permissions can also be changed by any process with an effective UID of 0.
This function contributes to satisfy the security requirement FDP_ACC.1, FDP_ACF.1, FMT_MSA.1, FMT_SMF.1,
FMT_MSA.3.
6.2.5 Object Reuse (OR)
Object Reuse is the mechanism that protects against scavenging, or being able to read information that is left over from
a previous subject’s actions. Three general techniques are applied to meet this requirement in the AIX 5.2b Distributed
System: explicit initialization of resources on initial allocation or creation, explicit clearing of resources on release or
deallocation, and management of storage for resources that grow dynamically.
Explicit initialization is appropriate for most TSF-managed abstractions, where the resource is implemented by some
TSF internal data structure whose contents are not visible outside the TSF: queues, datagrams, pipes, and devices. These
resources are completely initialized when created, and have no information contents remaining.
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Explicit clearing is used in AIX 5.2b only for directory entries, because they are accessible in two ways: through TSF
interfaces both for managing directories and for reading files. Because this exposes the internal structure of the resource,
it must be explicitly cleared on release to prevent the internal state from remaining visible.
Storage management is used in conjunction with explicit initialization for object reuse on files, and processes. This
technique keeps track of how storage is used, and whether it can safely be made available to a subject.
The following sections describe in detail how object reuse is handled for the different types of objects and data areas
and how the requirements defined in FDP_RIP.2 are satisfied.
6.2.5.1 Object Reuse: File System Objects (OR.1)
All file system objects (FSOs) available to general users are accessed by a common mechanism for allocating disk
storage and a common mechanism for paging data to and from disk. This includes the Journaled File System (JFS2) and
Network File System (which exists physically as a JFS2 volume on a server host). It includes both normal and large
JFS2 file systems.
Object reuse is irrelevant for the CD-ROM File System (CDRFS) because it is a read-only file system and so it is not
possible for a user to read residual data left by a previous user. File systems on other media (tapes, diskettes.) are
irrelevant because of warnings in the Security Guide not to mount file systems on these devices.
For this analysis, the term FSO refers not only to named file system objects (files, directories, device special files,
named pipes, and UNIX domain sockets) but also to unnamed abstractions that use file system storage (symbolic links
and unnamed pipes). All of these, except unnamed pipes, device special files and UNIX domain sockets, have a
directory entry that contains the pathname and an inode that controls access rights and points to the disk blocks used by
the FSO.
In general, file system objects are created with no contents, directories and symbolic links are exceptions, and their
contents are fully specified at creation time.
6.2.5.1.1 Object Reuse: Files
Storage for files is allocated automatically in pages as a file grows. These pages are cleared before they become
accessible, within the file. However, when a file is deleted the space holding the data from the file, both in memory and
on disk, is not cleared. This data will persist until the space is assigned to another file, when it will be cleared. These
internal fragments of deleted files are protected by the kernel to prevent accessing of deleted data.
If data is read before it is written, it will read only as zeroes. Reads terminate when the end-of-file (EOF) is detected. It
is possible to seek past the EOF, but any reads will return zeros. File writes may cause the file to grow, thus overwriting
any residual data and moving the EOF. If the file is seeked past the EOF and then written, this leaves a hole in the file
that will subsequently be read as zeroes.
6.2.5.1.2 Object Reuse: Directories and Directory Entries
In part, object reuse for directories is handled as for ordinary files: pages allocated are always cleared before being
incorporated into the directory. When a directory is first created, it is explicitly initialized to have the entries "." and "..",
but the remainder of the directory’s storage is cleared.
Individual directory entries are manipulated as distinct resources, such as when referencing file system objects, and as
part of the directory, such as when reading the entire directory itself. When a directory entry is removed or renamed the
space occupied by that directory entry is either combined with the previous entry as free space or else the i-node number
of the entry is set to zero when the entry occurs on a 512 byte boundary.
When a directory entry does not occur on a 512-byte boundary, the size of the preceding directory entry is incremented
by the size of the directory entry which has been removed. The space in a directory entry in excess of that which is
needed to store the necessary information may be allocated when a directory entry is to be created. The fields of the
directory entry remain unchanged.
When a directory entry occurs on a 512-byte boundary, the i-node number is set to zero to indicate that this entry is now
available for re-use. All other fields of the directory entry remain unchanged.
The directory entry is no longer visible to interfaces which perform file name operations and may only be seen when the
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entire directory is examined and the process has read access to the directory.
6.2.5.1.3 Object Reuse: Symbolic Links
Symbolic links have their contents (the link pathname) fully specified at creation time, and the readlink operation
returns only the string specified at creation time, not the entire contents of the block it occupies.
6.2.5.1.4 Object Reuse: Device Special Files
All device special files are initialized to a known state on first open and never grow. Device special files refer to actual
hardware or else to virtualized objects. There are no filesystem blocks, unless the device references a filesystem (in
which case the mechanism for object reuse of file system objects apply). Nor is there memory, unless the device is
associated with memory (in which case the object reuse mechanisms for memory objects apply).
6.2.5.1.5 Object Reuse: Named Pipes
FIFOs are created empty. Buffers are allocated to contain data written to a pipe, but the read and write pointers are
managed to ensure that only data that was written to the pipe can ever be read from it.
6.2.5.1.6 Object Reuse: Unnamed Pipes
Unnamed pipes are created empty. Buffers are allocated to contain data written to a pipe, but the read and write pointers
are managed to ensure that only data that was written to the pipe can ever be read from it.
6.2.5.1.7 Object Reuse: Socket Special File (UNIX Domain)
UNIX domain sockets have no contents; they are fully initialized at creation time.
This function contributes to satisfy the security requirement FDP_RIP.2 and „Subject Residual Information Protection”
(Note 1).
6.2.5.2 Object Reuse: IPC Objects (OR.2)
AIX 5.2b shared memory, message queues, and semaphores are initialized to all zeroes at creation. These objects are of
a finite size (shared memory segment is from one byte to 256 MBytes, semaphore is one bit), and so there is no way to
grow the object beyond its initial size.
No processing is performed when the objects are accessed or when the objects are released back to the pool.
This function contributes to satisfy the security requirement FDP_RIP.2 and „Subject Residual Information Protection”
(Note 1).
6.2.5.3 Object Reuse: Queuing System Objects (OR.3)
6.2.5.3.1 Object Reuse: Batch Queue Entries
cron and at jobs are defined in batch files, which are subject to the object reuse protections specified for files as
described previously.
This function contributes to satisfy the security requirement FDP_RIP.2 and „Subject Residual Information Protection”
(Note 1).
6.2.5.4 Object Reuse: Miscellaneous Objects (OR.4)
6.2.5.4.1 Object Reuse: Process
A new process’s context is completely initialized from the process’s parent when the fork system call is issued. All
program visible aspects of the process context are fully initialized. All kernel data structures associated with the new
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process are copied from the parent process, then modified to describe the new process, and are fully initialized.
The AIX kernel zeroes each memory page before allocating it to a process. This pertains to memory in the program’s
data segment and memory in shared memory segments. When a process requests more memory, the memory is
explicitly cleared before the process can gain access to it.
When the kernel performs a context switch from one thread to another, it saves the previous thread’s General Purpose
Registers (GPRs) and restores the new thread’s GPRs, completely overwriting any residual data left in the previous
thread’s registers. Floating Point Registers (FPRs) are saved only if a process has used them. The act of accessing an
FPR causes the kernel to subsequently save and restore all the FPRs for the process, thus overwriting any residual data
in those registers.
Processes are created with all attributes taken from the parent. The process inherits its memory (text and data segments),
registers, and file descriptors from its parent. When a process execs a new program, the text segment is replaced
entirely.
This function contributes to satisfy the security requirement FDP_RIP.2 and „Subject Residual Information Protection”
(Note 1).
6.2.6 Security Management (SM)
This section describes the functions for the management of security attributes that exist within AIX 5.2b.
6.2.6.1 Roles (SM.1)
The configuration of AIX 5.2b that is subject to this evaluation does not use the full roles and privilege concepts of
AIX. Instead a simplified role model is used., that just supports two roles: administrators and normal users.
In the evaluated confguration a user has the role of an administrator when he is allowed to su to root. Root itself will not
be used as a userid where a user can directly log in to. So every administrator has his/her own userid, which is used to
log into the system and which will appear in all audit records produced by this user. This allows to trace also
administrator activities to individual users.
6.2.6.1.1 Administrators
Users that are allowed to su to root can perform administrative actions (provided they also know the password required
to su to root). Users that don’t have the privilege to use su in their user profile can not perform administrative actions
even if they know the root password.
6.2.6.1.2 Normal Users
Normal users can not perform actions that require administrator privileges. They can only execute those setuid root
programs they have access to. In the evaluated configuration this is restricted to those programs they need like the
passwd program that allows a user to change his/her own password.
This function contributes to satisfy the security requirement FMT_SMR.1.
Note: AIX 5.2b supports a finer role concept but this is not part of the evaluated configuration. In the evaluated
configuration only users and administrators exist where administrators operate with root privileges.
6.2.6.2 Audit Configuration and Management (SM.2)
Audit control consists of the files used to maintain the configuration of the audit subsystem and a description of the
AUDIT command and its associated parameters
Table 6-1. Audit Control Files. The audit control files maintain the configuration for the auditing subsystem.
Defines whether bin mode auditing is enabled, the names of
the files used to store audit data and the names of the available
classes. Also defines the audit classes, i. e. for each audit class
/etc/security/audit/config
Description
Audit Control File
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Contains a record for each user which specifies which classes
will apply to the user account
/etc/security/user
Contains the post-processing command or commands for bin
mode auditing
/etc/security/audit/bincmds
Contains a list of the objects whose access will be audited
/etc/security/audit/objects
Defines audit events to be used on the system. An event needs
to be defined in this file to be formatted correctly.
/etc/security/audit/events
the audit events belonging to the class are defined
Description
Audit Control File
There are two different types of audit event selection: per-user and per-object. Per-user auditing allows the administrator
to specify specific classes of audit events that will be recorded for that user. Each process stores a copy of the audit
classes that apply to that user as part of the process table. An audit class is a subset of the total number of audit events
available and is defined in the file /etc/security/audit/config.
Per-object auditing allows the administrator to specify file system objects that will be audited. This is defined in the file
/etc/security/audit/objects. There for indicidual objects the audit event for the access modes that one wants to be audited
is defined.
These objects can be audited based on accesses of a specified mode (read/write/execute) and record the result of the
access attempt (success/failure).
The audit command is used to start and stop the auditing subsystem, to temporarily switch the auditing subsystem on or
off, and to query the audit subsystem for the current audit parameters.
The audit command is started from the host’s rc initialization script, as stated in the Security Guide.
The on and off parameters of the audit command enable and disable audit, without modifying the current configuration
that is stored in the kernel. The on parameter can have an additional parameter, panic, which causes the system to shut
down if bin data collection is enabled and records cannot be written to one of the bin files. The bin mode panic option
can also be specified in /etc/security/audit/config.
When the audit command is issued with the shutdown parameter, the collection of audit records is halted, and all audit
configuration information is flushed from the kernel’s tables. All audit records are flushed from the kernel’s buffers and
processed. The collection of audit data is halted until the next audit start command is entered.
When the audit command is issued with the start parameter, the following events occur:
• the /etc/security/audit/config file is read
• the /etc/security/audit/objects files is read and the objects that will be audited based on access are written into
kernel tables
• the audit class definitions are written into kernel tables from /etc/security/audit/config
• the auditbin daemon is started, depending on the options in /etc/security/audit/config
• auditing is enabled for users specified in the user’s stanza of the /etc/security/audit/config file
• auditing is turned on, with panic mode enabled or turned off, depending on what mode is specified in
/etc/security/audit/config
This allows to audit all the events defined in FAU_GEN.1. The events that are audited can be selected on a per user
basis, per event basis and per object basis using the configuration files described above.
This contributes to satisfy the requirements of FAU_GEN.1, FAU_SEL.1, FMT_MTD.1 „Audit Events”, FMT_MTD.1
„Audit Trail” and FMT_SMF.1.
A description of the structure of those files and the syntax of the entries can be found in AIX 5.2b Files Reference
document.
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6.2.6.3 Access Control Configuration and Management (SM.3)
Acess control to objects is defined by the permission bits and by the Access Control Lists (for those objects that have
access control lists asscociated with them). Default access permission bits are defined in the system configuration files
that define the value of the access control bits for objects being created without explicit definition of the permission bits.
The system administrator can define and modify those default values.
Permissions can changed by the object owner and the system administrator. When an object is created the creator is the
object owner. Object ownership can be transferred except for TCP ports, where the owner always remains the system
administrator. In the case of IPC objects, the creator will always have the same right as the owner, even when the
ownership has been transferred.
This function contributes to satisfy the security requirements FMT_MSA.1, FMT_MSA.3, FMT_SMF.1 and
FMT_REV.1 „Object Attributes”.
6.2.6.4 Management of User, Group and Authentication Data (SM.4)
6.2.6.4.1 Creating new Users
An administrator can create a new user and assigns a unique userid to this user. The initial password has to be defined
using the passwd command. The new user will be disabled until the initial password is set.
Attributes that can be set for each user are among others (a complete list can be found in the description of the chuser
command and the description of the content of the file /etc/security/user):
y Lock attribute (i. e. temporarily locking a user account)
y Administrative status of the user
y List of audit classes for the user
y List of groups the user belongs to
y Home directory for this user
y Number of consecutive unsuccessful login attempts allowed before the user account is locked
y Password parameter including the maximum and minimum age of a password, minimum length, difference to the
old password etc.
Those attributes are stored in the file /etc/security/user.
6.2.6.4.2 Modification of user attributes
User attributes can be modified by the system administrator. Modifications of user attributes require the modification of
the administration database that contains the user attributes (mainly /etc/security/user).
6.2.6.4.3 Management of Authentication Data
The system administrator has the capability to define rules and restrictions for passwords used to authenticate users. The
parameter available are:
minage Minimum number of weeks that must pass before a password can be changed.
maxage Maximum number of weeks that can pass before a password must be changed.
maxexpired Maximum number of weeks beyond maxage that a password can be changed before administrative action
is required to change the password. (Root is exempt.)
minalpha Minimum number of alphabetic characters the new password must contain.
minother Minimum number of nonalphabetic characters the new password must contain. (Other characters are any
ASCII printable characters that are nonalphabetic and are not national language code points).
minlen Minimum number of characters the new password must contain.
maxrepeats Maximum number of times a character can be used in the new password.
mindiff Minimum number of characters in the new password that must be different from the characters in the old
password.
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histexpire Number of weeks that a user is unable to reuse a password.
histsize Number of previous passwords that cannot be reused.
dictionlist List of dictionary files checked when a password is changed. Dictionary files contain passwords that are
not allowable.
Users are also allowed to change their own password using the passwd command. The password restrictions defined by
the system administrator apply.
This list of attributes satisfies those required by FIA_ATD.1. In addition this function contributes to satisfy the security
requirements FIA_SOS.1, FMT_MTD.1 „User Attributes”, FMT_MTD.1 „Authentication Data”, FMT_SMF.1 and
FMT_REV.1 „User Attributes”.
6.2.6.5 Time Management (SM.5)
AIX 5.2b provides the standard Unix functions to manage the system clock. The time can be set or modified by an
administrator. Modifications to the system time are audited (if configured) allowing a system administrator to extract the
differences between the „old” and „new” value of the system clock. The value of the system clock can not be
manipulated by normal users.
This satisfied the requirements of FPT_STM.1.
6.2.7 TSF Protection (TP)
While in operation, the kernel software and data are protected by the hardware memory protection mechanisms
described in the high level design and the hardware reference manuals of AIX 5.2b. The memory and process
management components of the kernel ensure a user process cannot access kernel storage or storage belonging to other
processes.
Non-kernel TSF software and data are protected by DAC and process isolation mechanisms. In the evaluated
configuration, the reserved user ID root, or other reserved IDs equivalent to root, owns TSF directories and files In
general, files and directories containing internal TSF data (e.g., audit files, batch job queues) are also protected from
reading by DAC permissions.
The TSF and the hardware and firmware components are required to be physically protected from unauthorized access.
The system kernel mediates all access to the hardware mechanisms themselves, other than program visible CPU
instruction functions.
The boot image for each host in the distributed system is adequately protected. A description of the boot logical volume
can be found in section 5.3.16, Initialization and Shutdown.
6.2.7.1 TSF Invocation Guarantees (TP.1)
All system protected resources are managed by the TSF. Because all TSF data structures are protected, these resources
can be directly manipulated only by the TSF, through defined TSF interfaces. This satisfies the condition that the TSF
must be "always invoked" to manipulate protected resources.
Resources managed by the kernel software can only be manipulated while running in kernel mode.
Processes run in user mode and can call functions of the kernel only as the result of an exception or interrupt. The
hardware and the kernel software handling these events and ensure that the kernel is entered only at pre-determined
locations, and within pre-determined parameters. All kernel managed resources are protected such that only the kernel
software is able to manipulate them.
Trusted processes implement resources managed outside the kernel. The trusted processes and the data defining the
resources are protected as described above depending on the type of interface. For directly invoked trusted processes the
program invocation mechanism ensures that the trusted process always starts in a protected environment at a
predetermined point. Other trusted process interfaces are started during system initialization and use well defined
protocol or file system mechanisms to receive requests.
Some system calls or parameter of system calls are reserved are reserved for trusted processes. When called the kernel
checks that the calling process runs with an effective userid of 0.
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This function contributes to satisfy the security requirement FPT_RVM.1.
6.2.7.2 Kernel (TP.2)
The AIX 5.2b software consists of a privileged kernel and a variety of non-kernel components (trusted processes). The
kernel operates on behalf of all processes (subjects).
The kernel runs in the CPU’s privileged mode and has access to all system memory. All kernel software, including
kernel extensions and kernel processes, execute with kernelprivileges but only defined subsystems within the kernel are
part of the TSF. The kernel is entered by some event that causes a context switch such as a system call, I/O interrupt, or
a program exception condition.
Upon entry the kernel determines the function to be performed, performs it, and, when finished, performs another
context switch to return to user processing (eventually on behalf of a different subject).
The kernel is shared by all processes, and manages system wide shared resources. It presents the primary programming
interface for AIX 5.2b in the form of system calls.
Because the kernel is shared among all processes, any process running "in the kernel" (that is, running in privileged
hardware state as the result of a context switch) is able to directly reference the data structures that implement shared
resources.
The major components of the kernel are memory management, process management, the file system, the low-level I/O
system, and the kernel extensions like implementing for example network protocols (IP, TCP, UDP, and NFS).
This function contributes to satisfy the security requirement FPT_SEP.1.
6.2.7.3 Kernel Extensions (TP.3)
Kernel extensions are dynamically loaded code modules that add function to the kernel. They include device drivers,
virtual file systems (e.g., NFS), inter process communication methods (e.g., named pipes), networking protocols, and
other supporting services. Kernel extensions can be loaded only at system boot in the evaluated configuration.
Kernel extensions run with kernel privilege, similarly to kprocs. However, extensions differ from kprocs in that the
kernel does not schedule them. Instead, kernel extensions are invoked from user processes by system calls, or internal
calls within the kernel, or started to handle external events such as interrupts.
Kernel extensions run entirely within the kernel protection domain. An extension may export system calls in addition to
those exported by the base AIX kernel. User-domain code can only access these extensions through the exported system
calls, or indirectly via the system calls exported by the base kernel.
Device drivers are kernel extensions that manage specific peripheral devices used by the operating system. Device
drivers shield the operating system from device-specific details and provide a common I/O model for user programs to
access the associated devices. For example, a user process calls read to read data, write to write data, and ioctl to
perform I/O control functions.
This function contributes to satisfy the security requirement FPT_SEP.1.
6.2.7.4 Trusted Processes (TP.4)
Trusted processes in AIX 5.2b are processes running in user mode but with root privileges. Some high-level TSF
functions are performed by trusted processes particularly those providing distributed services.
A trusted process is distinguished from other user processes by the ability to affect the security policy. Some trusted
processes implement security policies directly (e.g., identification and authentication) but many are trusted simply
because they operate in an environment that confers the ability to access TSF data (e.g., programs run by administrators
or during system initialization).
Trusted processes have all the kernel interfaces available for their use, but are limited to kernel-provided mechanisms
for communication and data sharing, such as files for data storage and pipes, sockets and signals for communication.
The major functions implemented with trusted processes include user login, identification and authentication, batch
processing, audit data management and reduction, some network operations, system initialization, and system
administration.
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The kernel will check for each system call that requires root privileges if the process that issued the call has those
privileges. If not, the kernel will refuse to perform the system call. The kernel will also for each access to an object
protected by the any of DAC mechanism check, if the process has the required access rights for the attempted type of
access.
Any program executed with root privileges has the ability to perform the actions of a trusted process. It is therefore
important that a site operating AIX strictly controls those programs and prohibits that those programs are modified or
that programs from untrusted sources are executed with root privileges.
Trusted processes are not part of the kernel and (except for those processes that perform system initialization and
identification and authentication) not part of the TSF itself.
Trusted processes provide a contribution to security management and identification and authentication. For
identification and authentication they contribute to satisfy the security functional requirements FIA_UAU.2,
FIA_UAU.7 and FIA_UID.2.
This function also contributes to FPT_SEP.1.
Note: Trusted processes may use system management commands or system calls as mentioned in the section on
supporting functions that are not part of the TSF. But in any case the kernel will verify that the process has the right to
perform the system call with the parameter specified by the caller and has the right to access all files with the intended
access mode.
6.2.7.5 TSF Databases (TP.5)
Table 6-4 identifies the primary TSF databases used in AIX 5.2b and their purpose. These are listed both as individual
files (by pathname) or collections of files.
With the exception of databases listed with the User attribute (which indicates that a user can read, but not write, the
file), all of these databases shall only be accessible to administrators. None of these databases shall be modifiable by a
user other than the system administrator.
Those databases are part of the file system and therefore the file system protection mechanisms of the TOE have to be
used to protect those databases from unauthorized access. It is the task of the persons responsible for setting up and
administrating the system to ensure that the access control features of the TOE are used throughout the lifetime of the
system to protect those databases.
When the system comprises more than one machine, the administrative databases are shared between the hosts. A single
master copy of the databases is maintained on an administrative server and made available for NFS-mounting by all the
hosts in the system. A particular user or group has the same identity on all hosts in the system. Some databases are
maintained independently on each host in the system, while others are synchronized through sharing.
Table 6-4 . Administrative Databases. This table lists other administrative files used to configure the TSF.
Defines all of the audit events that are recognized by the system and the form of
their tail data.
/etc/security/audit/events
Specifies who and what is going to be audited, where the bin audit data will reside,
and how auditing will be performed.
/etc/security/audit/config
Specification of TCP port, host (or subnet), and user/group at that host or subnet
allowed access to the port.
/etc/security/acl
Specifies the pipeline of commands to be performed by the auditbin daemon.
/etc/security/audit/bincmds
Contains hostnames and their address for hosts in the network. This file is used to
resolve a hostname into an Internet address in the absence of a domain name
server.
/etc/hosts
Stores group names, supplemental GIDs, and group members for all system
groups.
/etc/group
Stores user names, UIDs, primary GID, home directories for all system users.
/etc/passwd
contains commands to srcmaster daemon that starts other system daemons.
/etc/inittab
Stores time/date of last successful and unsuccesful login attempts for each user.
Stores the number of unsuccessful login attempts since the last successful one.
/etc/security/lastlog
Purpose
Database
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Defines the privileged ports as part of the access control on TCP ports
/etc/security/priv
Defines supplementary data about users, including audit status, required password
characteristics, access to su command.
/etc/security/user
Specification of service names to be used by DACINET in the style of
/etc/services.
/etc/security/services
Defines user passwords in one-way encrypted form, plus additional characteristics
including previous passwords, password quality parameters.
/etc/security/passwd
Specifies file system objects whose access is to be audited along with for what
access modes it will be done.
/etc/security/audit/objects
Purpose
Database
These tables are not functions but they are part of the management of the TSF. As such they contribute to the system
management security functional requirements FAU_SEL.1, FMT_MSA.3 and FMT_MTD.1 (Audit Trail, Audit Events,
User Attributes and Authentication Data) as well as FMT_SMF.1.
6.2.7.6 Internal TOE Protection Mechanisms (TP.6)
All kernel software has access to all of memory, and the ability to execute all instructions. In general, however, only
memory containing kernel data structures is manipulated by kernel software. Parameters are copied to and from process
storage (i.e., that accessible outside the kernel) by explicit internal mechanisms, and those interfaces only refer to
storage belonging to the process that invoked the kernel (e.g., by a system call). Functions implemented in trusted
processes are more strongly isolated than the kernel. Because there is no explicit sharing of data, as there is in the kernel
address space, all communications and interactions between trusted processes take place explicitly through files and
similar mechanisms.
This encourages an architecture in which specific TSF functions are implemented by well-defined groups of processes.
This function contributes to satisfy the security requirement FPT_SEP.1.
6.2.7.7 Diagnosis (TP.7)
AIX 5.2b provides a diagnosis program that can be used to check the correct operation of the underlying hardware of
the system. This program can be executed by administrators or by hardware maintenance personnel. Results of the
diagnosis program are stored in the diagnostic error log file, which can be protected by the discretionary access control
functions of AIX against access by normal users.
This function contributes to satisfy the security requirement FPT_AMT.1. The error log file contributes also to
FAU_GEN.1
6.3 Supporting functions not part of the TSF
6.3.1 System Management Tools
The evaluated configuration of AIX 5.2b provides the „System Management Interface Tool” (SMIT) for administration.
This tool provides a more convenient way for an administrator to perform the administration activities. The web based
administration tool WebSM is not included in the evaluated configuration and shall therefore not be used for system
administration when operating the evaluated configuration of AIX 5.2b.
SMIT itself is just a front-end tool which provides the administrator with a nice interface. SMIT generates scripts that
use the system management commands provided by AIX. The administrator can review the shell scripts before they are
executed by hitting the function key F6 before he executes the script.
In addition the administrator can use the commands provided by AIX for system management activities. Those
commands are also seen as part of the system management tools.
This function contributes to satisfy the security requirements associated with the management of security attributes.
Note: System management tools and commands do not enforce any part of the TOE security policy. They just provide
the tools for the administrator to perform his administrative functions. The TSF still check that the caller is allowed to
invoke the system calls used by those tools and checks that the caller has the required access rights to the objects (like
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configuration files) he is going to access. SMIT generates a script with commands that the administrator can check
before it is executed. Therefore SMIT itself is not seen as part of the TSF. The commands themselves are also bound by
the restrictions imposed by the system call interface and the access rights to the files in the administrative database.
6.3.2 User Processes
The AIX 5.2b TSF primarily exists to support the activities of user processes. A user, or non-TSF, process has no
special privileges or security attributes. The user process is isolated from interference by other user processes primarily
through the CPU execution state and address protection mechanisms and the way they are used by the kernel, and also
through the protections on TSF interfaces for process and file manipulation.
User processes are by definition untrusted and therefore do not contribute to any security function. The TSF ensure that
user processes are encapsulated in such a way that they are separated from the TSF and from processes (trusted and
untrusted) running with different attributes and will only be able to communicate with them using the defined TSF
interfaces. User processes therefore do not contribute to any security function of the TOE.
6.4 Assurance Measures
The following table provides an overview, how the assurance measures of EAL4 are met by AIX 5.2b.
Part of the documentation (especially for the development environment and the configuration management) will be
basically identical to the documentation providee previously for the ITSEC E3 evaluations of AIX 4.2 and AIX 4.3. It is
intended to reuse the evaluation results from those evaluations where possible.
Table 6-4: Mapping Assurance Requirements to Documentation
Administartor guidance is provided in the System Management Guide documents as
AGD_ADM.1
A separate document describing the Security Policy Model is provided to the
evaluation facility.
ADV_SPM.1
The correspondence information will be provided as part of the functional specification
and the high level design. An additional document providing the correspondence to the
TOE Summary Specification will be provided to the evaluation facility.
ADV_RCR.1
Low level design documentation is provided for all subsystems that implement TSF.
These are updates of the low level design documents provided for the previous
evalautions with some new documents describing new components of AIX 5.2b.
ADV_LLD.1
The full source code of the parts of AIX that build the TSF is provided for the
evaluation.
ADV_IMP.1
The high level design is described in an overview document and subsystem specific
documents. For example the high level design of the kernel the subsystems is described
in: [KAS], the high level design of the communication subsystem is described in
[COM], the description of the basic data structures used by the kernel and the trusted
functions are described in [FR].
ADV_HLD.2
The functional specification id provided in the documents [CR] Volume 1 to 6 and
[BOS].
ADV_FSP.2
Installation, generation and start-up procedures are described in [SMG] and [SMC].
Network aspects are addressed in [NIMG]
ADO_IGS.1
Delivery procedures are unchanged from the previous evaluations. Those results will
be reused. A separate document describes the delivery process.
ADO_DEL.2
IBM has a problem tracking procedure in place that covers all aspects of ACM_SCP.2.
This description is included in the documentation of the configuration management and
the software development procedures..
ACM_SCP.2
See above
ACM_CAP.4
CMVC is the tool used for configuration management of AIX source code,
documentation test plans and test cases. The configuration management procedures and
tools are identical to the ones used for previous versions of AIX that have been
evaluated under the ITSEC scheme. The procedures are are described in separate
documents. Compared to previous evaluations more documentation is now under
CMVC control.
ACM_AUT.1
Documentation describing how the requirements are met
Assurance Component
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A vulnerability analysis will be provided that describes IBM’s approach to identify
vulnerabilities of AIX 5.2b as well as the results of the findings.
AVA_VLA.2
The Strength of Function Analysis will be provided as an update of the Strength of
Mechanism Analysis provided for the ITSEC E3 evaluation.
AVA_SOF.1
The misuse analysis will be provided as an update to the Ease of Use Analysis
provided for the ITSEC E3 evaluation.
AVA_MSU.2
All the required resources to perform their own tests are provided to the evaluation
facility to perform their test. The evaluation facility will perform and document the
tests.
ATE_IND.2
Testing will be performed on different platforms that are defined in the Security
Target. Test results are documented such that the tests can be repeated.
ATE_FUN.1
See above
ATE_DPT.1
Detailed test plans are produced to test the functions of AIX 5.2b. Those test plan
include an analysis of the test coverage, an analysis of the functional interfaces tested
and an analysis of the testing against the high level and low level design.
ATE_COV.2
See above
ALC_TAT.1
The life cycle definition is described in separate documents. This addresses the
software development process as well as the description of the tools used for
development and how they are used.
ALC_LCD.1
The defect handling procedure IBM has in place for the development of AIX requires
to describe the defect with its effects, security implications, fixes and required
verification steps. Defects are managed within the configuration management system
and can therefore be easily tracked for each version of the TOE. The configuration
management system also allows to check at any time the status of the defect and the
corrective actions taken.
ALC_FLR.1
The security procedures on the development site have not changed from the previous
evaluations. Those procedures are described in general documents that apply for IBM
as a whole as well as site specific documents and specific documents for eServer
development.
ALC_DVS.1
User guidance is provided in the System User’s Guide documents. Security aspects
will be addressed in the document „AIX 5.2b Security Guide”.
AGD_USR.1
well as in the document [NIMG]. Security aspects are addressed in the document „AIX
5.2b Security Guide”.
Documentation describing how the requirements are met
Assurance Component
6.5 TOE Security Functions requiring a Strength of Function
The TOE has one security function (IA.1) that is implemented by a probabilistic or permutational mechanism. This is
the authentication mechanism that uses passwords for user authentication. The strength claimed for this function is
SOF-medium.
As explained above the System Administrator has several options he can use to force the users to select passwords that
are not easy to guess. In addition the TOE limit the number of attempts an attacker has to guess passwords in a try and
error method.
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7 Protection Profile Claims
7.1 PP Reference
This Security Target claims conformance with the „Controlled Access Protection Profile” (CAPP) Version 1.d,
8 October 1999. This Protection Profile was developed by the „Information System Security Organisation” of the
National Security Agency of the United States of America.
This Protection Profile is listed on the TPEP web site of NSA as a „Certified Protection Profile”.
This Protection Profile was also used as the basis of the evaluation of Sun Solaris 8 performed in the UK.
7.2 PP Tailoring
There is one additonal security functional requirement (FMT_SMF.1) that has been added to those defined in the CAPP.
The reason is AIS 32, Final Interpretation 065, where the new family FMT_SMF is defined and dependencies from
FMT_MSA.1 and FMT_MTD.1 to the new component FMT_SMF.1 have been added. To resolve those new
dependencies, FMT_SMF.1 has been added as a security functional requirement in addition to those defined in the
CAPP.
Two SFRs (FIA_UAU.1 and FIA_UID.1) defined in the PP have been substituted by hierarchical superior ones
(FIA_UAU.2 and FIA_UID.2). This does not affect the compliance to the Protection Profile. Since those components
don’t imply additional dependencies, the dependency analysis performed on the Protection Profile still applies.
Security Functional Requirements have been refined where required by the Protection Profile.
One organizational security policy and threats have been added (the Protection Profile only defines policies). One
assumption on the TOE environment (A.NET_COMP) has been added to reflect the distributed nature of the TOE.
The following security objectives for the TOE environment have been added:
OE.ADMIN
OE.INFO_PROTECT
OE.MAINTENANCE
OE.RECOVER
OE.SOFTWARE_IN
OE.SERIAL_LOGIN
OE.PROTECT
OE.HW_SEP
OE.LPAR
Those objectives are required to cover the specific threats addressing the TOE environment. All objectives are related to
physical and procedural security measures and therefore address the TOE non-IT environment.
In addition the Security Target has added security requirements for the IT environment (the processor used) to define
the requirement for the underlying processor to provide the functions to implement effective separation of the TSF from
untrusted software. This includes the requirements FDP_ACC.1, FDP_ACF.1 and FMT_MSA.3 for the IT environment.
As well, security requirements for the IT environment have been added to address the necessary protection of hardware
resources assigned to the TOE against access by software running in other partitions when running in an LPAR
environment (FDP_ACC.1 (LPAR) and FDP_ACF.1 (LPAR)).
The assurance requirements of the Protection Profile are those defined in the Evaluation Assurance Level EAL3 of the
Common Criteria. This Security Target specifies an Evaluation Assurance Level EAL 4 augmented by ALC_FLR.1.
Since the Evaluation Assurance Levels in the Common Criteria define a hierarchy, all assurance requirements of the
Protection Profile are included in this Security Target. ALC_FLR.1 which has been added to the assurance requirements
defined in the CAPP has no dependency on any other security functional requirement or security assurance requirement
and is therefore an augmentation that has no effect on the security functional requirements or security assurance
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requirements stated in the Protection Profile.
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8 Rationale
The rationale section provides additional information and demonstrates that the security objectives and the security
functions defined in the previous chapter are consistent and sufficient to counter the threats defined in chapter 2.
The rationale is based on the rationale already provided in the Controlled Access Protection Profile. In accordance with
the „Guide for the production of protection profiles and security targets” [GUIDE], only those aspects are discussed that
are additional to the rationale provided in [CAPP].
8.1 Rationale for additional Threats, Assumptions and Organizational
Security Policies
The CAPP does not lists threats but only addresses the following policies:
y P.AUTHORIZED_USERS
y P.NEED_TO_KNOW
y P.ACCOUNTABILITY
Those policies are also listed in this Security Target.
In addition, a new policy has been added with respect to the LPAR environment:
y P.STATIC
[CAPP] also lists the following assumptions:
y A.LOCATE
y A.PROTECT
y A.MANAGE
y A.NO_EVIl_ADM
y A.COOP
y A.PEER
y A.CONNECT
Two assumptions have been added, since they had also been part of previous Security Targets for AIX (ITSEC Security
Target for AIX 4.3):
y A.UTRAIN
y A.UTRUST
Another assumption
y A.NET_COMP
has been added to reflect the distributed nature of the TOE.
The Security Target has added a list of threats to be countered by the TOE or the TOE environment.
Threats countered by the TOE are:
y T.UAUSER
y T.UAACCESS
y T.UAACTION
Threats countered by the TOE environment are:
y TE.HWMF
y TE.COR_FILE
y TE.HW_SEP
y TE.LPAR
8.1.1 Rationale for additonal Assumptions
A.UTRAIN has been added as an assumption because it was also mentioned in the ITSEC Security Target for AIX.
A.UTRAIN makes the assumption that users are trained well enough to use the security functionality provided by the
system appropriately. This addresses the aspect of access control, where a user is responsible to manage access control
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rights for file system and IPC objects he owns. Users that need to protect their assets from unauthorized access by other
authorized users of the system need to understand the implications of managing the access rights to file system objcts
and IPC objects they own.
User need also to be trained in the protection of their authentication data in the TOE environment.
A.UTRUST has been added as an assumption because it was also mentioned in the ITSEC Security Target for AIX.
A.UTRUST makes the assumption that users are trusted some tasks or group of tasks within a secure IT environment by
excercising complete control over their data. This also addresses the aspect of access control where user are trusted to
use the access control mechanism provided by the TOE appropriately. Users should not blaim the system for the loss of
integrity and / or confidentilaity of data they own when they don’t use the access control mechanism provided by AIX
appropriately.
A.NET_COM has been added as an assumption to reflect the fact that the TOE is used in a distributed environment
where network components are involved in the communication. It is assumed that those network components do not
modify data transmitted over the network. This assumption is necessary, since some TSF rely on the correctness of data
transmitted over the network.
8.1.2 Ratinale for the inclusion of Threats
The Protection Profile has derived all security objectives from the organizational security policies listed in the
Protection Profile. The authors of this Security Target decided to include also threats the TOE is going to counter as
well as threats that need to be countered in the environment. Since also all the policies and assumptions defined in the
Protection Profile have been included in the Security Target, the inlcusion of threats is not a violation of the
conformance claim to the Security Target.
Note: There are other examples of evaluations where the Security Targets claims conformance with [CAPP] and where
threats have been defined.
8.1.3 Rationale for additional Organizational Security Policies
All policies from [CAPP] have been adopted by the ST. In addition, P.STATIC has been added to harmonize the use of
LPAR-enabled hardware as underlying systems in the IT environment.
8.2 Security Objectives Rationale
The following tables provide a mapping of security objectives to the environment defined by the threats, policies and
assumptions, illustrating that each security objective covers at least one threat, assumption or policy and that each threat,
assumption or policy is covered by at least one security objective.
8.2.1 Security Objectives Coverage
Marked elements are stipulated by CAPP.
Table 8-1: Mapping Objectives to threats , assumptions and policies
P.AUTHORIZED_USERS, P.NEED_TO_KNOW, P.ACCOUNTABLE
O.ENFORCEMENT
P.AUTHORIZED_USERS, P.NEED_TO_KNOW, P.ACCOUNTABLE,
T.UAUSER, T.UAACTION
O.MANAGE
P.KNEED_TO_KNOW, T.UAACCESS
O.RESIDUAL_INFO
T.UAUSER, T.UAACTION, P.ACCOUNTABLE
O.AUDITING
T.UAACCESS, P.NEED_TO_KNOW
O.DISCRETIONARY_ACCESS
T.UAUSER, P.AUTHORIZED_USERS
O.AUTHORIZATION
Threat / Policy
Objective
Table 8-2: Mapping objectives for the environment to threats, assumptions and policies
A.MANAGE, A.NO_EVIL_ADMIN
OE.ADMIN
Threat / Assumption / Policy
Env. Objective
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TE.LPAR
OE.LPAR
TE.HW_SEP
OE.HW_SEP
A.COOP
OE.CREDEN
A.LOCATE, A.PROTECT, A.CONNECT
OE.PHYSICAL
TE.COR_FILE, A.NET_COMP, A.CONNECT
OE.PROTECT
A.CONNECT
OE.SERIAL_LOGIN
P.NEED_TO_KNOW
OE.SOFTWARE_IN
TE.HWMF, TE.COR_FILE
OE.RECOVER
TE.HWMF
OE.MAINTENANCE
TE.COR_FILE, A.PROTECT, A.UTRAIN, A.UTRUST
OE.INFO_PROTECT
TE.COR_FILE, A.MANAGE, A.NO_EVIL_ADMIN, A.PEER,
A.NET_COMP, P.STATIC
OE.INSTALL
Table 8-3: Mapping threats to objectives
OE.LPAR
TE.LPAR
OE.HW_SEP
TE.HW_SEP
OE.PROTECT, OE.INSTALL, OE.INFO_PROTECT, OE.RECOVER
TE.COR_FILE
OE.MAINTENANCE, OE.RECOVER
TE.HWMF
O.AUDITING, O.MANAGE
T.UAACTION
O.DISCRETIONARY_ACCESS, O.RESIDUAL_INFO
T.UAACCESS
O.AUTHORIZATION, O.AUDITING, O.MANAGE
T.UAUSER
Objective
Threat
Table 8-4: Mapping Assumptions to Objectives
Objective
Assumption
OE.INFO_PROTECT
A.UTRUST
OE.INFO_PROTECT
A.UTRAIN
OE.SERIAL_LOGIN, OE.PROTECT, OE.PHYSICAL
A.CONNECT
OE.INSTALL
A.PEER
OE.PROTECT, OE.INSTALL
A.NET_COMP
OE.CREDEN
A.COOP
OE.ADMIN, OE.INSTALL
A.NO_EVIL_ADMIN
OE.ADMIN, OE.INSTALL
A.MANAGE
OE.INFO_PROTECT, OE.PHYSICAL
A.PROTECT
OE.PHYSICAL
A.LOCATE
Table 8-5: Mapping Policies to Objectives
Objective
Policy
OE.INSTALL
P.STATIC
O.AUDITING, O.MANAGE, O.ENFORCEMENT
P.ACCOUNTABLE
O.DISCRETIONARY_ACCESS, O.MANAGE, O.ENFORCEMENT,
O.RESIDUAL_INFO, OE.SOFTWARE_IN
P.NEED_TO_KNOW
O.AUTHORIZATION, O.MANAGE, O.ENFORCEMENT
P.AUTHORIZED_USERS
8.2.2 Security Objectives Sufficiency
T.UAUSER: The threat of impersonization of an authorized user by an attacker is sufficiently diminished by
O.AUTHORIZATION requiring proper authorization of users gaining access to the TOE and O.AUDITING which
requires the collection of evidence of security relevant actions, which includes authorization attempts. O.MANAGE
ensures that only authorized administrators (which are assumed to be trustworthy) have the ability to add new users or
modify the attributes of users. Together those objectives ensure that no unauthorized user can impersonate as an
authorized user.
T.UAACESS: The threat of an authorized user of the TOE accessing information resources without the permission from
the user responsible for the resource is removed by O.DISCRETIONARY_ACCESS requiring access control for
resources and the ability for authorized users to specify the access to their resources. This ensures that a user can access
a resource only if the requested type of access has been granted by the user responsible for the management of access
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rights to the resource. In addition O.RESIDUAL_INFO ensures that an authorized user can not gain access to the
information contained in a resource after the resource has been released to the system for reuse.
T.UAACTION: The threat of undetected security policy violation is removed by O.AUDITING requiring the TOE to
collect evidence of security relevant actions and make it accessible to authorized administrators. O.MANAGE provides
a system administrator with the capability to manage the audit system such that it is capable to monitor all critical
aspects of the security policy.
TE.HWMF: The threat of losing data due to hardware malfunction is mitigated by OE.MAINTENANCE requiring the
invocation of diagnostic tools during preventative maintenance periods. In addition OE.RECOVER requires the
organizational procedures to be set up that are able to recover critical data and restart operation in a secure mode in the
case such a hardware malfunction happens.
TE.COR_FILE: The threat of undetected loss of integrity of security enforcing or relevant files of the TOE is
diminished by OE.INSTALL requiring procedures for secure distribution, installation and configuration of systems
therby ensuring that the system has a secure inital state with the required protection of such files, OE.PROTECT
requiring protection of transferred data in a distributed system and OE.INFO_PROTECT requiring procedures for the
appropriate protection of those files when the system is up and running. OE.RECOVER ensures that the system is
securely recovered, which includes the verification of the integrity of security enforcing or security relevant files as part
of the recovery procedures.
TE.HW_SEP: The threat that the underlying hardware does not provide the functions required to implement an efficient
self-protection of the TSF such that the TSF themselves and the TSF data can be efficiently protected from unauthorized
access and modification by untrusted software is addressed by the objective OE.HW_SEP for the processor used to
execute the TOE software. This is a basic fundamental requirement for secure operating systems where trusted and
untrusted software are executed on the same processor using the same memory space and the same processor resources.
For TSF self-protection a processor feature is required that controls access to processor resources and main memory
such that the TSF can implement a self-protection function in the way that the TSF reserve processor resources and
memory areas for themselves and prohibit that those resources can be used by non-TSF software.
TE.LPAR: The threat that software running in another logical partition than the TOE itself, therefore having different
hardware resource of the same machine assigned to it than the TOE, is addressed by the objective OE.LPAR, requiring
from the IT environment (i.e. the underlying machine) to successfully restrict access to resources that are assigned to
one logical partition to the operating system running in that partition, therefore preventing access from software in other
partitions to the TOE’s logical partition.
A.LOCATE: The assumption on physical protection of the processing resources of the TOE is covered by
OE.PHYSICAL requiring physical protection.
A.PROTECT: The assumption on physical protection of all hard- and software as well as the network and peripheral
cabling is covered by the objectives OE.INFO_PROTECT demanding the approval of network and peripheral cabling
and OE.PHYSICAL requiring physical protection.
Note: Phsical protection of the network components and cabling is required by A.PROTECT which may seem to be
redundant to A.CONNECT. But A.CONNECT also addresses protection against passive wiretapping, which may be
done without having physical access to a hardware component.
A.MANAGE: The assumption on competent administrators is covered by OE.ADMIN requiring competent and
trustworthy administrators and OE.INSTALL requiring procedures for secure distribution, installation and configuration
of systems.
A.NO_EVIL_ADMIN: The assumption on administrators that are neither careless nor wilfully negligent or hostile is
covered by OE.ADMIN requiring competent and trustworthy administrators and OE.INSTALL requiring procedures for
secure distribution, installation and configuration of systems.
A.COOP: The assumption on authorized users to act in a cooperating manner is covered by the ojective OE.CREDEN
requiring the safe storage and non-disclosure of authentication credentials.
A.NET_COMP: The assumption on network components to not modify transmitted data is covered by the objective
OE.PROTECT requiring procedures and/or mechanisms to ensure a safe data transfer between systems as well as
OE.INSTALL requiring proper installation and configuration of all parts of the distributed system thus including also
components that are not part of the TOE.
A.PEER: The assumption on the same management control and security policy constraints for systems with which the
TOE communicates is covered by OE.INSTALL requiring procedures for secure distribution, installation and
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configuration of the distributed system.
A.CONNECT: The assumption on controlled access to peripheral devices and protected internal communication paths is
covered by OE.SERIAL_LOGIN for the protection of attached serial login devices, OE.PROTECT for the protection of
data transferred between workstations and OE.PHYSICAL requiring physical protection.
A.UTRAIN: The assumption on trained users is covered by OE.INFO_PROTECT which requires that users are trained
to protect the data belonging to them.
A.UTRUST: The assumption on user to be trusted to protect data is covered by OE.INFO_PROTECT which requires
that users are trusted to use the protection mechanims of the TOE adequately to protect their data.
P.AUTHORIZED_USERS (see CAPP section 7.1.2): The policy demanding that users have to be authorized for access
to the system is implemented by O.AUTHORIZATIONand supported by O.MANAGE allowing the management of this
functions an O.ENFORCEMENT ensuring the correct invocation of the functions.
P.NEED_TO_KNOW (see CAPP section 7.1.2): The policy to restrict access to and modification of information to
authorized users which have a „need to know” for that information is implemented by O.DISCRETIONARY_ACCESS
demanding an appropriate access control. It is supported by O.RESIDUAL_INFO ensuring that resources do not release
such information during reuse and by OE.SOTWARE_IN preventing users other than authorized administrators from
installing new software that might affect the access control functionality. O.MANAGE allows administrators to manage
this functions, O. ENFORCEMENT ensures that the functions are invoked and operate correctly.
P.ACCOUNTABLE (see CAPP section 7.1.2): The policy demanding accounting for user actions is implemented by
O.AUDITING requiring auditing for security relevant actions and supported by O.MANAGE for the management of
this functionality and O.ENFORCEMENT ensuring the correct invocation.
P.STATIC: The policy ensures, by demanding appropriate organizational measures, that no additional object reuse
issues are imposed with the support of logical partitioning by the TOE: while the TOE provides functionality to support
the dynamic allocation and release of hardware resources during operation, such dynamic partitioning by the use of a
Hardware Management Console for the underlying hardware must not be performed by an administrator while the TOE
is running. This is implemented by OE.INSTALL, demanding a secure installation and configuration of TOE systems,
which applies also to the underlying hardware.
8.3 Security Requirements Rationale
Since this Security Target does not identify additional security functional requirements for the TOE to the SFRs already
defined in the CAPP (except for FMT_SMF.1), the security requirements rationale is widely adopted from this
Protection Profile by simple reference.
FMT_SMF.1 has been added to achive compliance with AIS 32, Final Interpretation 065, which defines dependencies
of FMT_MSA.1 and FMT_MTD.1 (which are included in this Security Target) to this new component. It was identified
that FMT_SMF.1 should be included mentioning the areas of management listed in the instantiations of FMT_MSA.1
and FMT_MTD.1 in the Security Target.
No security functions for the non-IT environment have beed added, since the procedures that need to be implemented
can (and probably will) be different for each site running the evaluated version of AIX. Therefore no specific security
functional requirements and security functions for the non-IT environment have been defined in this Security Target.
Individual sites running AIX should validate that the procedures and physical security measures they have put in place
are sufficient to cover the security objectives defined for the environment of the TOE in this Security Target.
Security requirements for the IT environment have been added to define the support required by the TOE from the
underlying processor. As with every operating system that also runs untrusted software, some kind of separation
mechanism must exists that prohibits the untrusted software from tampering with trusted software and TSF data. In the
case of this TOE the processor must supply a separation mechanism such that memory areas as well as hardware
privileges required to directly access devices or memory management functions are protected from direct access by
untrusted software. This is defined with an access control policy called „memory access control policy” that the
underlying processor must support. This policy is expressed using FDP_ACC.1 and FDP_ACF.1 as well as
FDP_MSA.3 from part 2 of the Common Criteria.
In addition, security requirements for the IT environment have been added to address the threat that arises from running
the TOE in an environment that provides logical partitions to allow the processing of several operating systems on one
machine. To such logical partitions, dedicated processors, memory ranges and I/O slots are assigned - to protect the TSF
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and TSF data, this requires means to prevent access to resources that are assigned to the TOE by other operating
systems. This is expressed using FDP_ACC.1 (LPAR) and FDP_ACF.1 (LPAR) defining an appropriate access control
policy.
Section 8.3.3 provides more detailed rationale for the selection of the security functional requirements for the IT
environment.
8.3.1 Security Requirements Refinements Rationale
This section provides tha rationale for the selections and refinements made in the security requirements section for the
security requirements defined in the CAPP.
In FAU_GEN.1 the table was augmented with the names of the audit events as defined for AIX 5.2b. The table shows
that all events that the CAPP requires to be audited one or more audit events of AIX 5.2b can be associated with.
In FAU_SAR.3 the refinement shows the additional fields of the audit records that can be used in the evaluation of the
audit record database using the auditselect command.
In FAU_SEL.1 the capability of AIX 5.2b to define auditable events not only based on the user id but also based on the
object (in this case: files) and the based on the event type is specified and further explained in the security function
AU.2
For FAU_STG.3 the threshold value is defined as an absolute value as defined as one possible option in the rationale of
the CAPP.
In FAU_STG.4 the possibility of AIX 5.2b to count the number of audit records lost for auditable events of an
authorized administrator is expressed. Normally the system would be configured to stop when the audit trail is full
(which is a hard, but acceptable way to prevent the auditable events).
In FDP_ACC.1 the different objects that AIX 5.2b controls with a discretionary access control function are listed. Since
the Controlled Access Protection Profile has only one instantiation of FDP_ACC.1, FDP_ACF.1 and FMT_MSA.1, it
was decided to subsume all the discretionary access control sub-policies under a single instantiation of those security
functional requirements. Although it is agreed that this does not support readability of the Security Target, we view this
approach as possible in the CC framework and compliance with the CAPP is maintained.
FDP_ACF.2 gets somewhat complicated with expressing the different policies for discretionary access control for the
different types of objects. It was decided to list the rules for file system objects, IPC objects and TCP ports separately
because they differ significantly.
In FIA_ATD.1 the audit classes have been added as the only additional security attribute of users within the evaluated
configuration of AIX 5.2b. Other attributes as for example stored in the file /etc/security/users are not seen as security
attributes.
In FIA_USB.1 the way how AIX 5.2b associates the real, effective and audit user id is expressed. While the effective
user id and group id can change as the result of a su command or a program with the setuid or setgid attribute set, the
real and audit user id are maintained and allow to trace activities to the real user that originated them.
In FMT_REV.1 „Revocation of User Attributes” the delayed revocation method has been added, since this is the
standard way AIX 5.2b behaves. To get immediate revocation the administrator has to force the user to log off after he
has made the modifications to the users attribute. According to the rationale in the Controlled Access Protection Profile
this method is seen as appropriate to satisfy this requirement.
In FMT_REV.1 „Revocation of Object Attributes” the AIX 5.2b implementation of delayed revocation is defined. This
is in accordance with the rationale defined in the Controlled Access Protection Profile.
FMT_SMF.1 has been added to comply with AIS 32, Final Interpretation 065 and the dependencies defined there. The
Protection Profile defines management requirements in FMT_MSA.1 and the five instantiations of FMT_MTD.1 for
y Object security attributes management
y User attribute management
y Authentication data management
y Audit trail management
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y Audit event management
those aspects are listed in this security functional requirement.
FMT_SMR.1 defines no additional roles than those identified in the Protection Profile. Although AIX 5.2b in general
provides the capability for a more fine grained role model, the lack of guidance on the configuration and use of such an
extended role model in the user documentation has led to the decision to exclude this capability from the evaluated
version. This is compliant with the application note in the Protection Profile as well as with the handling of this aspect
in previous ITSEC and TCSEC evaluations.
FPT_AMT.1 describes the capability of an authorized administrator to start a separate diagnostic system that tests the
underlying hardware. It should be mentioned that some basic checks are included in the system’s init process and are
performed during start-up of the system. Those checks are part of the underlying firmware and not part of AIX 5.2b.
8.3.2 Security Requirements Coverage
Section 7.2.2 of the Controlled Access Protection Profile provides a table mapping security objectives for the TOE to
the security functional requirements. In addition this section of the Protection Profile also provides a discussion with the
detailed evidence of the coveage for each security objective. In accordance with [GUIDE] this rationale is seen as
sufficient for discussion of the coverage of security requirements for those objectives and security requirements taken
directly from the Protection Profile.
This section therefore only discusses those security functional requirements that are different from the ones listed in the
Protection Profile.
Security functional requirements FIA_UAU.1 and FIA_UID.1 have been replaced by FIA_UAU.2 and FIA_UID.2
which both are stronger requirements than those defined in the Protection Profile. FIA_UAU.1 and FIA_UID.1 are both
mapped to the objectives O.AUTHORIZATION, which requires requires that only authorized users gain access to the
TOE and its resources. While FIA_UAU.1 and FIA_UID.1 both allow to define actions a user can porform without
being properly identified and authenticated, no action is allowed by FIA_UAU.2 and FIA_UID.2. Therefore
FIA_UAU.2 and FIA_UID.2 are much more in line with the objective stated by O.AUTHORIZATION than the security
functional requirements defined in the Protection Profile.
Security functional requirement FMT_SMF.1 has been included as an additional functional requirement to address the
objective O.MANAGE. Security management within the TOE consists of the management of user attributes (addressed
by FMT_MTD.1 „Management of User Attributes”), management of object security attributes (addressed by
FMT_MSA.1), management of the audit trail (addressed by FMT_MTD.1 „Management of the Audit Trail”),
management of the audit events (addressed by FMT_MTD.1 „Management of Audited Events”) and management of
authentication data (addressed by FMT_MTD.1 „Management of Authentication Data”).
In addition to the rationale provided in the Protection Profile the following table shows that each security functional
requirement addresses at least one objective.
Table 8-6: Mapping Security Functional Requirements to Objectives
O.AUDITING
FAU_STG.4
O.AUDITING
O.MANAGE
FAU_STG.3
O.AUDITING
FAU_STG.1
O.AUDITING
O.MANAGE
FAU_SEL.1
O.AUDITING
O.MANAGE
FAU_SAR.3
O.AUDITING
FAU_SAR.2
O.AUDITING
O.MANAGE
FAU_SAR.1
O.AUDITING
FAU_GEN.2
O.AUDITING
FAU_GEN.1
Objectives
SFR
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O.AUDITING
FPT_STM.1
O.ENFORCEMENT
FPT_SEP.1
O.ENFORCEMENT
FPT_RVM.1
O.ENFORCEMENT
FPT_AMT.1
O.MANAGE
FMT_SMR.1
O.MANAGE
FMT_SMF.1
O.DISCRETIONARY_ACCESS
FMT_REV.1
Obj. Attributes
O.DISCRETIONARY_ACCESS
O.MANAGE
FMT_REV.1
User Attributes
O.AUTHORIZATION
O.MANAGE
FMT_MTD.1
Authen. Data
O.MANAGE
FMT_MTD.1
User Attributes
O.AUDITING
O.MANAGE
FMT_MTD.1
Audit Events
O.AUDITING
O.MANAGE
FMT_MTD.1
Audit Trail
O.DISCRETIONARY_ACCESS
FMT_MSA.3
O.DISCRETIONARY_ACCESS
FMT_MSA.1
O.DISCRETIONARY_ACCESS
O.AUDITING
FIA_USB.1
O.AUTHORIZATION
FIA_UID.2
O.AUTHORIZATION
FIA_UAU.7
O.AUTHORIZATION
FIA_UAU.2
O.AUTHORIZATION
FIA_SOS.1
O.AUTHORIZATION
O.DISCRETIONARY_ACCESS
FIA_ATD.1
O.RESIDUAL_INFO
Note 1
O.RESIDUAL_INFO
FDP_RIP.2
O.DISCRETIONARY_ACCESS
FDP_ACF.1
O.DISCRETIONARY_ACCESS
FDP_ACC.1
O.MANAGE
8.3.3 Rationale for Security Requirements for the IT environment
In addition to the requirements of [CAPP] this Security Target has added security requirements for the IT environment.
The requirements FDP_ACC.1, FDP_ACF.1 and FMT_MSA.3 define the need for an access control policy
implemented in the underlying processor that allows to reserve the access and manipulation of critical processor and
memory resources to specially software (instructions) operating with a defined privilege attribute (usually called
„supervisor” or „system” mode). The TSF have to ensure that no untrusted software will ever execute with this
privilege. Based on this the TSF can then control the access to memory objects and other processor resources and
implement the high level access control functions as well as the TSF self protection.
To do this the underlying processor has to provide a basic access control mechanism where access to processor
resources (like registers) and memory areas is controlled based on a processor attribute where the implementation of the
TSF ensure that untrusted software never executes with this attribute. This is expressed with FDP_ACC.1 and
FDP_ACF.1. Since the processor may allow read access to specific registers for software running without „supervisor”
privilege, FDP_ACF.1.3 is used to define this.
The requirements don’t define the exact rules because those may differ slightly for different processor types without
getting into the problem of interoperability problems. For example a new processor may implement additional
instructions and additional register but still be fully downwards compatible. Since software developed for the older
versions of the processor will not use the additonal instructions and will not touch the additional register, the claims for
the software still hold although the objects controlled by the new processor differ from those controlled by the old
processor. Of course, if anybody wants to evaluate a PowerPC based processor those rules have to be defined precisely
for the specific processor type that is the target of the hardware evaluation.
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The „static attribute initialization” (FMT_MSA.3) is here defined as the value of the processor attribute („user” or
„supervisor”) at the start-up of the processor (after reset or power-up). This has to be „permissive” since the register and
memory areas need to be initialized. It is therefore necessary that the software that perform those initalization activities
is part of the TSF.
These security requirements for the IT environment address the security objective OE.HW_SEP since the memory
access control policy allows the TOE to protect the TSF and the TSF data from unauthorized access by untrusted
software. The TOE has to use the memory access control policy to allow memory access by untrusted software just to
those memory areas that belong to the untrusted software itself. Access to special hardware register will be managed by
the TSF such that this access will always be reserved to trusted software. This shows that the security requirements for
the IT environment are sufficient to protect the TSF and TSF data from unauthorized access and modification when
used correctly by the TOE.
In addition, the security requirements FDP_ACC.1 (LPAR) and FDP_ACF.1 (LPAR) have been chosen to express the
need for an access control policy implemented in the underlying hardware to regulate access to parts of the hardware
that are assigned to different logical partitions (LPARs). If an LPAR enabled underlying machine allows to run several
operating systems in different logical partitions, with dedicated hardware resources assigned to those partitions, means
are required to prevent the operating system running in one partition from accessing the resources assigned to another
operating system running on the same machine.
Since the underlying hardware for the TOE provides LPAR support, access to the TSF and TSF data from other logical
partitions than the one that belongs to the TOE must be prevented. Such protection has to be provided by the IT
environment, which is expressed in the security requirements meeting the objective OE.LPAR.
The following table shows the mapping of the security functional requirements for the IT environment to the security
objectives for the IT environment.
Table 8-7: Mapping Security Functional Requirements for the IT Environment to Objectives
OE.LPAR
FDP_ACF.1 (LPAR)
OE.LPAR
FDP_ACC.1 (LPAR)
OE.HW_SEP
FMT_MSA.3
OE.HW_SEP
FDP_ACF.1
OE.HW_SEP
FDP_ACC.1
Objective
SFR
8.3.4 Justification of explicitly expressed security requirements
The explicit requirement Note 1 is adopted from the CAPP, the substantiation of the CAPP applies: The CC’s FDP_RIP
components only specify resources being allocated to objects and does not address resources used directly by subjects,
such as memory or registers. This explicit requirement was added to ensure coverage of these resources. The words are
identical to FDP_RIP.2 except „subject” replaces „object”.
The name „Note 1” has been adopted from the Protection Profile for an easy mapping to the requirements defined there.
It is known to the authors of this Security Target that this name is not compliant with the recommendations for the
naming of components additional to the ones defined in part two of the CC.
8.3.5 Security Requirements Sufficiency
The internal consistency of the security functional requirements and the complete coverage of the defined security
objectives by security functional requirements is demonstrated in section 7.2 of the CAPP and applies for this Security
Target.
8.3.6 Security Requirements Dependency Analysis
The only security functional requirement added to the ones defined in the CAPP is FMT_SMF.1 as defined in AIS 32,
Final Interpretation 065. This component has no dependency. But since with AIS 32, Final Interpretation 065
dependencies of the components FMT_MSA.1 and FMT_MTD.1 to the new component FMT_SMF.1 have been
introduced, FMT_SMF.1 has been added to this Security Target to resolve those dependencies.
FIA_UAU.1 and FIA_UID.1 as defined in the CAPP have been replaced by the hierarchically higher components
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FIA_UAU.2 and FIA_UID.2. FIA_UAU.1 and FIA_UAU.2 have the same dependency on FIA_UID.1, which is
resolved by the inclusion of FIA_UID.2, which is hierarchical to FIA_UID.1. FIA_UID.1 and FIA_UID.2 both have no
dependency.
Since no other additional security functional requirements to those defined in the CAPP Protection Profile have been
defined for the TOE, the dependency analysis for the security functional requirements in section 7.3 of the Protection
Profile applies for all security requirements taken from the CAPP.
With respect to the security requirements for the IT environment the dependencies of FMT_MSA.3 on FMT_MSA.1
and FMT_SMR.1 are not resolved. This has been justified in the application note for FMT_MSA.3 in the definition of
the security requirements for the IT environment as well as in the chapter „Justification for unresolved dependencies”.
The dependency of FDP_ACC.1 on FDP_ACF.1 is resolved as well as the dependency of FDP_ACF.1 on FDP_ACC.1
and FMT_MSA.3. The dependencies of FMT_MSA.3 on FMT_MSA.1 and FMT_SMR.1 are not resolved as stated
earlier.
The dependency of FDP_ACF.1 (LPAR) for the IT environment on FMT_MSA.3 has not been resolved. This is left to
the author of the ST for the LPAR mechanism: The dependency of the TOE on access control to its resource has been
unambiguously expressed by the LPAR resource access control policy defined in FDP_ACC.1 (LPAR) and
FDP_ACF.1 (LPAR) - the static attribute initialization for this policy is considered an implementation issue that needs
not be defined within this ST and should be left to the ST defining the actual implementation. The mutual dependencies
between FDP_ACC.1 (LPAR) and FDP_ACF.1 (LPAR) have been resolved.
The dependency analysis for the pre-defined EAL4 has already been performed by the creators of the Common Criteria
and is not repeated in this section. ALC_FLR.1, which has been added as a security assurance requirement has no
dependency on any security functional or security assurance requirement. Therefore the dependency analysis for EAL4
of the Common Criteria applies.
Since EAL4 is hierarchical to EAL3, all dependencies of security functional requirements on assurance requirements
listed in the Protection Profile are also resolved.
8.3.7 Justification of unresolved dependencies
As demonstrated in the dependency analysis above, all dependencies between security requirements are resolved since
all the dependencies within the CAPP Protection Profile are resolved, EAL 4 as a pre-defined evaluation assurance level
contains no unresolved references to other assurance components and no additional references to functional
components and ALC_FLR.1 has no dependencies.
The dependencies of FMT_MSA.3 on FMT_MSA.1 and FMT_SMR.1 for the security requirements for the IT
environment are not resolved, because the processor does not allow to „manage” the use of the processor attribute and
there is no role model involved. The processor switches between „user” and „supervisor” mode under well defined
conditions where the TSF defined in this Security Target are required to „manage” those conditions. Roles (especially
human roles) are not involved here.
8.3.8 Strength of function
This Security Target claims in compliance with CAPP a SOF rating SOF-medium. This claim applies for FIA_SOS.1,
whereby CAPP states that a ‘one off’ probability of guessing the password in 1,000,000 is given. The SFR is in turn
consistent with the security objectives.
8.3.9 Evaluation Assurance Level
The EAL defined in the CAPP is EAL3, as CAPP addresses a generalized environment with a moderate level of risk to
the assets. This security target claims EAL4 augmented with ALC_FLR.1, meeting this assumptions on the environment
as well by providing a higher evaluation assurance level.
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8.4 TOE Summary Specification Rationale
8.4.1 Security Functions Justification
The following table shows that the IT security functions, as specified in the TOE summary specification, meet all
security functional requirements for the TOE and work together to satisfy the TOE security functional requirements.
Table 8-8: Mapping Security Functional Requirements to Security Functions
The passwd funtion of IA.1 is able to enforce the verification of secrets as required. System
management commands can be used to define parameters that can be used to (hopefully) enhance
FIA_SOS.1
Security attributes belonging to individual users are realized by the user I&A data management
of IA.1. Management of user attributes is described in SM.4.
FIA_ATD.1
The residual information protection as realized by OR.1, OR.2, OR.3 and OR.4 (see above)
applies as well to subjects.
Note 1
Object residual information protection is realized by security functions for object reuse on file
system objects (OR.1), IPC objects (OR.2), queing system objects (OR.3) and miscellaneous
objects (OR.4).
FDP_RIP.2
The discretionary access control is realized as described above by DA.1, DA.2, DA.3, DA.4 and
DA.5. There the individual mechanisms for access control depending on the object type are
described in detail.
FDP_ACF.1
The discretionary access control policy is based on DA.1 and DA.2 defining permission bits for
the subjects and objects as in DA.3 for file system objects, DA.4 for TCP connections and DA.5
for IPC objects.
FDP_ACC.1
Prevention of audit data loss is described in AU.6. The system can be configured to go into
„panic” mode and stop the host when the audit trail is full.
FAU_STG.4
AU.6 describes the process AIX takes when the audit trail exceeds a defined threshold.
FAU_STG.3
Audit data is protected by AU.5. This prevents audit records to be deleted or modified by other
users than the system administrator.
FAU_STG.1
The in- or exclusion of auditable events from the set of audited events is provided by SM.2 (audit
configuration and management). SM.2 describes how a system administrator can select the events
to be audited based on event type, file name and user identity and defines the system
configuration files used in this function System configuration files in general are also described in
TP.5.
FAU_SEL.1
The requirement to allow searches of the audit data based on specified attributes is met by the
audit review function described in AU.3 and AU.4. auditselect can be used as a tool to select
audit records using an expression based on the audit record fields listed in table 6.2. This table
contains all the selection criteria listed in FAU_SAR.3.
FAU_SAR.3
Read access to the audit records is granted only to explicitly privileged users as enforced by the
audit file protection of AU.5. (This function uses the access control functions for files as
described in DA.3 to protect the audit files from unauthorized access. Management of file access
rights is covered by SM.3 but all this is covered by AU.5).
FAU_SAR.2
The system administrator can use the commands described in AU.3 and AU.4 to select, read,
process and print audit records.
FAU_SAR.1
The association of auditable events with its causing identity is done in AU.1 specifying the audit
record format, including the user and login ID of the creator of the auditable event, and AU.2
generating the audit record. IA.2 and IA.3 describe the authentication process which ensures that
the ID of the a user is authenticated. IA.4 describes that although a user may change his / her
effective user ID, the login user ID (which is recorded in the audit record) can not be changed.
This ensures that the ID the user has used when he has authenticated to the system is recorded
with every audit event that this user has caused.
FAU_GEN.2
The requirement for the information to be recorded with an audit event are satisfied by the
generation of audit data is fulfilled by the security functions AU.1 specifying the audit record
format and SM.2 describing the audit control files which are used to define the events that can be
audited. AU.2 describes the process used within the TOE to generate an audit record. The results
of diagnostic tests are stored in a separate error log file as described in TP.7.
FAU_GEN.1
security functions (TOE summary specification)
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Reliable time stamps are provided by the protected system clock of the time management
function SM.5.
FPT_STM.1
The required domain separation for the TSF is realized by the kernel functionality TP.2 itself, the
kernel extensions TP.3, trusted processes TP.4, the discretionary access control mechanism DA.3
and internal TOE protection mechanisms TP.6.
FPT_SEP.1
The TSF invocation guarantee functionality TP.1 ensure that TSP enforcement functions are
always invoked before functions in the TSC are allowed to proceed.
FPT_RVM.1
Diagnostic functions are provided by TP.7 to allow abstract machine testing.
FPT_AMT.1
The required roles are maintained within the security management of the roles in function SM.1.
FMT_SMR.1
Management of security functions is addressed in the following security functions:
Object security attributes management: DA.3 (File system objects), DA.4 (TCP connections),
DA.5 (IPC objects). In addition SM.3 defines some management functions.
User attribute management: SM.4
Authentication management: SM.4 and IA.1
Audit trail management: SM.2
Audit event management: SM.2
In addition most of the management functions use the TSF databases (TP.5) to store mangement
configurations.
FMT_SMF.1
Revocation of object security attributes is realized by the access control configuration and
management function SM.3.
FMT_REV.1
Obj. Attributes
The revocation of user security attributes as required in FMT_REV.1 is realized by the user
management funcitons of SM.4.
FMT_REV.1
User Attributes
Initialization of authentication data is restricted to administrators during the creation of new users
in SM.4. Authentication data (in encrypted form) and attributes are stored in TSF databases
described in TP.5. Users are allowed to change their own authentication data within the limits
defined by the system administrator. This is described in SM.4
FMT_MTD.1
Authen. Data
User security attributes are protected as required by the user identification and authentication data
management IA.1 and during the creation of new users in SM.4. User attributes are stored in TSF
databases described in TP.5.
FMT_MTD.1
User Attributes
Only authorized administrators are allowed to modify or observe the set of audited events, which
is implemented by the audit configuration and management SM.2. Audit attributes are stored in
TSF databases described in TP.5.
FMT_MTD.1
Audit Events
The audit trail (and the restricted access to it) is realized by the audit file protection AU.5 and the
audit configuration and management SM.2. TSF databases as defined in TP.5 contain
configuration parameter of the audit trail.
FMT_MTD.1
Audit Trail
Restrictive default values for security attributes are defined for the objects when they are created.
Default values can be defined by the system administrator for all object types and by the user for
file system objects created under his control. (see above, i.e. SM.3, DA.3, DA.4, and DA.5).
Some default values are defined in TSF databases as defined in TP.5.
FMT_MSA.3
The management of object security attributes is implemented by the access control configuration
and management function SM.3, the objects are described in DA.3 (file system objects), DA.4
(TCP connections) and DA.5 (IPC objects).
FMT_MSA.1
The required binding between subjects and users is implemented by the su functionality of IA.4
and login processing of IA.5. Function IA.6 describes the logoff process which releases the
binding between subjects and users.
FIA_USB.1
Identification of each user before any action is realized together with authentication as in IA.2
and IA.3 (see above). Identification is initated by a trusted process. Trusted processes are
described in TP.4.
FIA_UID.2
The login mechanisms of IA.3 provide only obscured feedback during authentication.
Authentication feedback is managed by a trusted process. Trusted processes are described in
TP.4.
FIA_UAU.7
Authentication of each user before any action is realized by IA.2 (common authentication
mechanism) and IA.3 (interactive login and related mechanisms). Authentication is initated by a
trusted process. Trusted processes are described in TP.4.
FIA_UAU.2
the strength of the passwords chosen by the user. Password management including the possible
parameter to enhance the strength of passwords are explained in SM.4.
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This table shows, how the security functions work together to satisfy the security functional requirements.
CAPP contains a (quite short) justification why the requirements themselves are mutually supportive. Although the
Controlled Access Protection Profile has been evaluated and therefore no additional justification for the mutual support
of the security requirements is necessary (the additional requirement is justified by AIS 32 Final Interpretation 065),
here are some additional arguments for mutual support of the security functional requirements:
The requirements for auditing (FAU_GEN.1, FAU_GEN.2, FAU_SAR.1, FAU_SAR.2 FAU_SAR.3, FAU_SEL.1,
FAU_STG.2, FAU_STG.3 and FAU_STG.4) define the requirements for an audit system by defining the events the
TOE should be able to audit with the relation to the other security functional requirements. The association of each
event to the user’s identity is conistent with the requirement for user identification and authentication (FIA_UID.2 and
FIA_UAU.2), so FAU_GEN.2 has to basis to associate audit events with the user that caused the event. In addition the
requirement in FAU_GEN.1 to record the time and date of the event needs to be based on a reliable time stamp as
required by FPT_STM.1. FAU_SAR.1, FAU_SAR.2 and FAU_SAR.3 ensure that audit records can be reviewed on a
useful basis. In addition FAU_SEL.1 enables an administrator to avoid to be flooded with audit data by enabling him to
adapt the type of events that are actually audited to his needs.
Audit data only makes sense when the audit data is complete or when at least the administrator is warned before the
TOE gets into a state where auditing is no longer possible. FAU_STG.2 to FAU_STG.4 address this issue.
Access control is defined by a discretionary access control policy in FDP_ACC.1 and FDP_ACF.1. For AIX there are
three different types of objects with some differences in policies depending on the object type. To keep the compliance
with CAPP, those have been stated together. All the dependencies on the management aspects have been resolved. The
management of the three object types differ only slightly, where those differences are explained in FMT_MSA.1 and
FMT_REV.1.
Object reuse is a useful requirement to prohibit unwanted access to information via resources that have not been
prepared for reuse. Since the TOE supports access control, object resuse makes sense. This is addressed in FDP_RIP.2.
The requirement „Note 1” extends this to objects that are not directly related to objects covered by the discretionary
access control policy (like main memory).
Note from the authors of the ST: This should be discussed for the next release of the CC and the CAPP, because two
different requirements, especially when they are stated like this lead to confusion.
Identification and authentication is handled by FIA_ATD.1, FIA_SOS.1 FIA_UAU.2, FIA_UAU.7 FIA_UID.2 and
FIA_USB.1 in a fairly conventional way. FIA_USB describes the way the effective user ID and group ID can be
changed. Since the real user ID is the one taken for audit events, any change of the effective user ID will not result in a
false user ID in the audit records. Therefore FIA_USB is not contradicting FAU_GEN.2.
In the management section the requirements for the management of Audit Trail, Audited Events, User Attributes and
Authentication Data has been separated in the protection profile. Since they are clearly separated, they are not
contradicting each other.
Revocation for user attributes is described separately from revocation of object attributes in two instantiations of
FMT_REV.1. This makes sense, since revocation is handled differently. FMT_SMF.1 has been inlcuded because of AIS
32 Final Interpretation 065 and covers the different management aspects addressed in detail in FMT_MSA.1 and the
instantiations of FMT_MTD.1.
The TOE supports only two different roles as expressed by FMT_SMR.1. No additional role is required by any other
SFR, so the role model is consistent with the other requirements.
FPT_AMT.1 allows the administrator to perform tests of the underlying hardware to verify its correct operation. This is
not contradicting any other requirement and is useful to verify the correct operation.
FPT_RVM.1 is required to ensure that the security functions can not be bypassed. In addition FPT_SEP.1 ensures that
untrusted programs can not tamper with the TSF and cause them to operate in contradiction to the security policy of the
TOE. FPT_AMT.1, FPT_RVM.1 and FPT_SEP.1 are therefore mutually supportive requirements to enable a sufficient
self-protection of the TSF.
FPT_STM.1 is required by the audit requirement FAU_GEN.1, which needs a reliable time to be included in the audit
data. This allows the administrator to identify when an event has happened.
As a summary this shows that the security functional requirements are not contradicting each other and are mutually
supportive.
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8.4.2 Assurance Measures Justification
The TOE summary specification in section 6.4 includes a justification that each TOE security assurance requirement is
met by appropriate assurance measures.
8.4.3 Strength of function
The password mechanism used for authentication is the only mechanism in the TSF that is implemented by a
permutational or probabilistic mechanism. For the password based authentication mechanism of the security function
IA.1, a minimum strength of SOF-medium is claimed. This is done in accordance with the SOF claim for the related
security functional requirement FIA_SOS.1. There is no other mechanism in this Security Target where a strength of
function claim is required.
This claims is consistent with the security objctive O.AUTHORIZATION and the statement in section 3.2 which says
that the TOE should „protect against threats of inadvertent or casual attempts to breach the system security”. A highly
skilled and well funded attacker is explicitely excluded from the threat scenario described in section 3.2. Therefore a
strength of SOF-medium is consistent with the description of the TOE environment.
8.5 PP Claims Rationale
The TOE is conformant to the Controlled Access Protection Profile CAPP, as referenced in [CAPP].
No additional security objectives for the TOE have been defined. Objectives for the TOE environment have been added
to this ST in addition to the ones contained in CAPP to allow a more distinguished description of the TOE environment
- this does not impact the conformance of this ST to the PP.
All security functional requirements in this ST are inherited from the CAPP and the operations allowed / required by the
PP are performed and indicated in bold letters. Two security functional components (FIA_UAU.1 and FIA_UID.1) have
been replaced by hierarchical higher ones (FIA_UAU.2 and FIA_UID.2). In both cases the only difference is the fact
that no interaction with the TOE is allowed without proper user identification and authentication. This does not modify
any of the rationale provided in the PP. In addition FMT_SMF.1 has been added to comply with AIS 32 Final
Interpreatation 065, which defines dependencies of two security functional requirements (FMT_MSA.1 and
FMT_MTD.1 ) included in the PP. To satisfy those requirements the new security functional component has
FMT_SMF.1 has been added to the Security Target (anticipating that this security functional requirement will be added
in an update to the Controlled Access Protection Profile).
Additional SFRs for the TOE IT environment have been defined to cope with the more distinguished description of the
TOE environment - this does not impact the conformance of this ST to the PP.
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9 Abbreviations
Virtual Memory Manager
VMM
Virtual File System
VFS
User Datagram Protocol
UDP
TOE Security Functions
TSF
Target of Evaluation
TOE
Transmission Control Protocol
TCP
Security Target
ST
System Management Interface Tool
SMIT
Remote Shell
RSH
Remote Procedure Call
RPC
Protection Profile
PP
Portable Data Format
PDF
Network Install Manager
NIM
Network File System
NFS
Licensed Product Package
LPP
Logical Partitioning
LPAR
Logical File System
LFS
Journalled File System
JFS
International Standards Organization
ISO
Internet Protocol
IP
Institute of Electrical and Electronics Engineers
IEEE
International Electrotechnical Commission
IEC
Hypertext Markup Language
HTML
General Purpose Register
GPR
General Availability
GA
File Transfer Protocol
FTP
File System Object
FSO
Floating Point Register
FPR
Federal Information Processing Standard
FIPS
End of File
EOF
Discretionary Access Control for Internet Services
DACINET
Discretionary Access Control
DAC
Common Desktop Environment
CDE
Common Criteria
CC
Controlled Access Protection Profile
CAPP
Amerivan National Standards Institute
ANSI
Advanced Interactive Executive
AIX
AIX 5.2b Security Target
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