Security Target
packet filter 3.0.3
Authors: Christian Koob, Jörg Marx, secunet Security Networks AG
Certification-ID: BSI-DSZ-CC-0595
Version
1.0
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HISTORY
Version Date Change(s) Author(s)
1.0 16/08/2010 Version for evaluation body and
certification body
Christian Koob, Jörg Marx
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TABLE OF CONTENT
1 ST INTRODUCTION 7
1.1 ST REFERENCE AND TOE REFERENCE 7
1.2 TOE OVERVIEW 7
1.2.1 Usage, major security features and TOE type 7
1.2.2 Required non-TOE hardware/software/firmware 9
1.3 TOE DESCRIPTION 10
1.3.1 Physical scope of the TOE 10
1.3.2 Logical scope of the TOE 10
1.3.2.1 Audit Data 10
1.3.2.2 Information Flow Protection 10
1.3.2.3 Management 11
1.3.2.4 Components 11
2 CONFORMANCE CLAIM 12
2.1 CC CONFORMANCE CLAIM 12
2.2 PP AND SECURITY REQUIREMENT PACKAGE CLAIM 12
2.3 CC CONFORMANCE CLAIM RATIONALE 12
3 SECURITY PROBLEM DEFINITION 13
3.1 ASSETS 13
3.2 SUBJECTS 14
3.3 EXTERNAL ENTITIES 14
3.4 ASSUMPTIONS 15
3.5 THREATS 16
3.6 ORGANISATIONAL SECURITY POLICIES 16
4 STATEMENT OF SECURITY OBJECTIVES 17
4.1 SECURITY OBJECTIVES FOR THE TOE 17
4.2 SECURITY OBJECTIVES FOR THE OPERATIONAL ENVIRONMENT 18
4.3 SECURITY OBJECTIVES RATIONALE 19
4.3.1 Countering the threats 20
4.3.2 Covering the OSPs 20
4.3.3 Covering the assumptions 20
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5 STATEMENT OF SECURITY REQUIREMENTS 21
5.1 SECURITY FUNCTIONAL REQUIREMENTS FOR THE TOE 21
5.1.1 Security Audit 22
5.1.1.1 FAU_GEN.1 Audit data generation 22
5.1.2 User data protection (FDP) 22
5.1.2.1 FDP_IFC.1 Subset information flow control 22
5.1.2.2 FDP_IFF.1 Simple security attributes 23
5.1.3 User identification (UID) 24
5.1.3.1 FIA_UID.1 Timing of identification 24
5.1.4 Security management (FMT) 25
5.1.4.1 FMT_MSA.1 Management of security attributes 25
5.1.4.2 FMT_MSA.3 Static attribute initialization 25
5.1.4.3 FMT_SMF.1 Specification of management functions 26
5.1.4.4 FMT_SMR.1 Security roles 26
5.2 EXTENDED COMPONENTS DEFINITION 26
5.3 SECURITY ASSURANCE REQUIREMENTS FOR THE TOE 27
5.4 SECURITY REQUIREMENTS RATIONALE 28
5.4.1 TOE functional requirements rationale 28
5.4.2 Fulfilling the SFR dependencies 29
5.4.3 Security assurance requirements rationale 29
6 TOE SUMMARY SPECIFICATION 30
6.1 TOE SECURITY FUNCTIONALITY 30
6.1.1 SF1 Information Flow Protection 30
6.1.2 SF2 Security Audit 30
6.1.3 SF3 Management 31
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LIST OF TABLES
Table 1: Scope of TOE delivery 10
Table 2: secunet wall packet filter components 11
Table 3: Assets 13
Table 4: External entities 14
Table 5: Assumptions 15
Table 6: Threats 16
Table 7: Security Objectives for the TOE 17
Table 8: Security Objectives for the environment of the TOE 18
Table 9: Security Objective Rationale 19
Table 10: Security Functional Requirements for the TOE 21
Table 11: Chosen Evaluation Assurance Requirements 27
Table 12: Coverage of Security Objective for the TOE by SFR 28
Table 13: Fulfilling the SFR dependencies 29
LIST OF FIGURES
-
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COPYRIGHT
Copyright © 2010 by secunet Security Networks AG
This document is for internal use only. Further publications, reprints, duplications or recordings —
no matter in which form, of the entire document or parts of it — are only permissible with the prior
consent of secunet Security Networks AG. Likewise this document must only be handed on to third
parties within the framework of a corresponding non-disclosure and return declaration.
Apart from explanations, evaluations and our own data collections this document contains
descriptions of manufactured products, interfaces and concepts which are based on the
publications of the respective manufacturers. Inasmuch as the document has disclosed internal
information of manufacturers, this information is marked in the document and is subject to special
secrecy.
Use of customary names, trade names, trade marks etc. in this document does not give rise to any
presumption that such names are to be regarded as being free within the meaning of the trademark
and brand protection acts. All brand and product are trademarks or registered trademarks of their
respective owners.
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1 ST INTRODUCTION
1.1 ST reference and TOE reference
Title: secunet wall packet filter Security Target
Sponsor: secunet Security Networks AG
Editor(s): Christian Koob, Jörg Marx, secunet Security Networks AG
Version Number: 1.0 (identical to version number 0.97)
Date: 16.08.2010
CC Version: Version 3.1, Revision 2
Assurance Level: EAL4+, that is EAL4 augmented by ALC_FLR.2
Certification-ID: BSI-DSZ-CC-0595
Keywords: Firewall, Packet Filter, Network Security, Information flow control
TOE name: secunet wall packet filter
TOE version: Version 3.0.3
1.2 TOE Overview
1.2.1 Usage, major security features and TOE type
This Security Target defines the security objectives and requirements for the secunet wall packet
filter (TOE), a software module of secunet Security Networks AG. secunet wall packet filter provides
packet filter functionality. secunet wall packet filter allows the integration of packet filter capability
into firewall or VPN components which are parts of secunet wall or SINA product family. Thus the
secunet wall packet filter is delivered to an application developer. The application developer
integrates the secunet wall packet filter into an application in order to build a network component.
The administrator of this application is defined as TOE end-user.
When IP networks with different levels of security are interconnected, this is usually done by
introducing special network components at the border of the networks. These components provide
firewall functionality and separate the two or more networks from each other on different levels of
the network stack. Data flow from one to another network can be allowed by a rule based policy
enforced by these network components.
The secunet wall packet filter consists of software on machines to implement packet filter
functionality for the network components; i. e. the secunet wall packet filter is part of the network
components. The secunet wall packet filter relies on information available at OSI layer 3 and layer 4
for policy enforcement. The functionality for packet filtering is part of the operating system (Linux).
The secunet wall packet filter supports IPv4 [4].
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The TOE major security features are:
„ The TOE enforces the Packet Filter information flow policy. This policy ensures that the TOE
will only forward data from and to the internal network if the information flow policy allows it.
„ The TOE collects audit data and sends it to a memory buffer in order to identify attempts to
violate a policy.
„ The TOE is capable of performing management functions such as modification of networks filter
traffic rules and configuration data.
„ The TOE verifies the identification information of an administrator provided by the environment
(application) before any management function can be performed.
The following security services are not part of the TOE and are thus to be provided by the IT
environment (application):
„ The environment allows the Identification and Authentication of an administrator
„ Sending of audit data to a dedicated machine in the protected network
The generation of networks filter traffic rules (policy) and configuration data takes place in the IT
environment. The IT environment provides NTP service and Syslog service.
After start-up of a network component that comprise the TOE and a secure initialisation process the
initial TOE configuration data is read via I/O-control interface in the TOE system start-up process.
The configuration data is the human readable content of the configuration file. The configuration
data comprise IP address- and network interface definition, static routes and other system
parameters. If no configuration data is available on start-up the TOE will not start-up automatically.
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1.2.2 Required non-TOE hardware/software/firmware
The TOE has the following minimal requirements concerning the physical machine they run on:
„ Intel i586 compatible CPU
„ PCI bus system
„ 128 MB RAM
„ two 100Mbit or 1000Mbit Ethernet Interfaces
„ storage entity (further requirements depend on the application)
„ Floppy drive or USB Controller or Compact Flash Adapter
The hardware must be compatible with the Linux operating system used for the application.
The physical connections are:
„ power supply
„ network interfaces
„ PS/2- or USB-attached keyboard
„ VGA graphics adapter
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1.3 TOE Description
1.3.1 Physical scope of the TOE
The TOE consists of several components that are all running in Kernel-Space on the Linux
operating system. These components are the following kernel parts: packet filter, management and
audit mechanism. All other parts of the system are considered to be environment of the TOE.
The TOE is delivered to an application developer. The TOE delivery includes the software secunet
wall packet filter and documentation. This documentation contains information for the application
developer and the TOE end-user. See the following table. The software module is electronically
signed.
Delivered TOE parts Version Remarks
secunet wall packet filter CD-ROM Version 3.0.3 secunet wall packet filter Software
documentation Version 1.0 Delivered as PDF on secunet wall packet
filter CD-ROM
Table 1: Scope of TOE delivery
1.3.2 Logical scope of the TOE
1.3.2.1 Audit Data
The TOE collects audit data and sends it to a memory buffer in order to identify attempts to violate
a policy. This allows the authorized administrator to inspect the current state of a network
component. The TOE generates audit records for
„ start-up and shutdown of the audit functions
„ datagrams received or sent through a network components network interfaces if they match
configured patterns
1.3.2.2 Information Flow Protection
The TOE enforces the Packet Filter information flow policy. This policy ensures that the TOE will
only forward data from and to the internal network if the information flow policy allows it. Therefore
the TOE implements the information flow control (as routers) on the network layer (IP) and transport
layer (TCP/UDP/ICMP). In order to apply the packet filter rules the network components take the
information from the IP and TCP/UDP/ICMP-Header (where applicable).
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1.3.2.3 Management
The TSF is capable of performing the following management functions:
„ Modification of network traffic filter rules
„ Modification of configuration data
The TOE verifies the identification information of an administrator provided by the environment
(application) before any management function can be performed. The TOE is initialized with a strict
packet filter rule set, i. e. everything is dropped.
1.3.2.4 Components
The secunet wall packet filter consists of several components. Table 2 shows which components
are parts of the TOE and part of the IT environment.
- IT environment TOE
Kernel - Packet filter
Audit mechanism
Management
User Space Secure transport mechanism
for configuration data and
audit data.
Management (Configuration
Tool)
-
Table 2: secunet wall packet filter components
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2 CONFORMANCE CLAIM
2.1 CC Conformance Claim
This Security Target and the TOE claim conformance to part 2 and part 3 of Common Criteria ([1]
and [2]):
Common Criteria Part 2 conformant
Common Criteria Part 3 conformant
2.2 PP and security requirement package claim
This Security Target does neither claim conformance to a Protection Profile nor to a security
requirement package.
2.3 CC Conformance Claim Rationale
As this Security Target does neither claim conformance to a Protection Profile nor to a security
requirement package a conformance claim rationale is not necessary.
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3 SECURITY PROBLEM DEFINITION
This chapter introduces the security problem definition of the TOE. This comprises:
„ The assets which have to be protected by the TOE.
„ The subjects which are interacting with the TOE.
„ The assumptions which have to be made about the environment of the TOE.
„ The threats which exist against the assets of the TOE
„ The organisational security policies the TOE has to comply to.
3.1 Assets
The following assets need to be protected by the TOE and its environment:
Asset Description
TSF Data
(Information Flow)
Audit data transmitted from the network components to the
management machine.
Configuration data transmitted from the management machine to
the network components.
TSF Data
(On the TOE)
TSF data stored on the TOE which are necessary for its own
operation. This includes packet filter rules or configuration data.
Resources The resources in the connected networks that the TOE components
are supposed to protect. The resources are outside the TOE
components.
Table 3: Assets
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3.2 Subjects
No active entity in the TOE that performs operations on objects is defined.
3.3 External entities
The following external entities may interact with the TOE:
External entity Description
Administrator The administrator of a network component is an entity that has
complete trust with respect to all policies implemented by the
TSF. He is in charge of installing and configuring the TOE as
well as performing the management functions of the TOE.
User Any entity (human or IT) outside the TOE that interacts (or
may interact) with the TOE. A goal of a user may be to access
or
modify sensitive information by sending IP packets to or
receiving from the components of the TOE. This includes
attacks from the protected networks behind the network
components as well as attacks from outside those networks.
Attackers with an Enhanced-Basic attack potential are
assumed.
Table 4: External entities
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3.4 Assumptions
The following assumptions need to be made about the IT environment of the TOE to allow the
secure operation of the TOE.
Assumption Description
A.ENV The TOE is used in a controlled environment. Specifically it is
assumed:
That only the administrator gains physical access to the TOE,
That the administrator handles the authentication secrets (see A.I&A)
with care, specifically that he will keep them secret and can use it in a
way that nobody else can read it.
A.NOEVIL The administrator of the TOE is non hostile, well trained and knows the
existing documentation of the TOE.
The administrator is responsible for the secure operation of the TOE.
A.SECINIT The TOE is securely initialised, i.e. that the initialisation is done
according the procedure described in the documentation [5].
A.INFLOW No information can flow between the internal and external networks
unless it passes through the TOE.
A.CONFW The network components (TOE and application) are configured in a
secure manner. Specifically it is assumed that no incoming
connections are accepted except protected data (e. g. SSH, [3]) from
the management machine.
A.TSP The IT environment provides reliable timestamps (NTP server).
A.PROT The data flow between the management machine and the network
components is protected by cryptographic transforms (e. g. SSH
authorization and SSH transport protection as defined in [3]).
A.AUDIT The IT environment provides a Syslog server and a means to present
a readable view of the audit data.
A.I&A The environment allows the Identification and Authentication of an
administrator.
Table 5: Assumptions
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3.5 Threats
The following threats have to be countered by the TOE. Hereby attackers with an enhanced-basic
attack potential are assumed.
Threat Description
T.BYPASS A user might attempt to bypass the security functions of the TOE in
order to gain unauthorized access to resources in the protected
networks.
E. g., a user might send non-permissible data through the TOE in
order to gain access to resources in protected networks by sending
IP packets to circumvent filters. This attack may happen from
outside the protected network.
T.WEAKNESS A user might gain access to the TOE in order to read, modify or
destroy TSF data by sending IP packets to the TOE and exploiting
a weakness of the protocol used. This attack may happen from
outside and inside the protected network. A user might also try to
access sensitive data of the TOE via its management interface.
Table 6: Threats
3.6 Organisational security policies
The TOE does not enforce organisational security policies.
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4 STATEMENT OF SECURITY OBJECTIVES
This chapter describes the security objectives for the TOE (in chapter 4.1), the security objectives
for the operational environment of the TOE (in chapter 4.2) and contains the security objectives
rationale.
4.1 Security Objectives for the TOE
The following security objectives have to be met by the TOE
Policy Description
O.MANAGEMENT The TOE verifies the identification information of an administrator
provided by the environment (application) before any management
function can be performed. The TOE must provide the necessary
management functions in order to modify the configuration data or
the traffic filter rules.
O.FILTER The TOE must filter the incoming and the outgoing data traffic of all
data between all connected networks according to the rule sets.
O.AUDIT The TOE must provide an audit trail of security-related events.
Table 7: Security Objectives for the TOE
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4.2 Security Objectives for the Operational Environment
The following security objectives have to be met by the operational environment of the TOE.
Policy Description
OE.ENV The TOE is used in a controlled environment. Specifically it is
assumed:
„ That only the administrator gains physical access to the TOE,
„ That the administrator handles the authentication secrets (see
A.I&A) with care, specifically that he will keep them secret and
can use it in a way that nobody else can read it.
OE.NOEVIL The administrator of the TOE shall be non hostile, well trained and
has to know the existing documentation of the TOE.
The administrator is responsible for the secure operation of the
TOE.
OE.SECINIT The TOE is securely initialised, i.e. that the initialisation is done
according the procedure described in the documentation [5].
OE.INFLOW The administrator must assure that the packet filter components
provide the only connection for the different networks.
OE.CONFW The network components (TOE and application) must be configured
to accept only protected data (e. g. SSH, [3]) from the management
machine.
OE.TSP The IT environment provides reliable timestamps
(NTP server).
OE.PROT The data flow between the management machine and the network
components is protected by cryptographic transforms (e. g. SSH
authorization and SSH transport protection as defined in [3]).
OE.AUDIT The IT environment provides a Syslog server and a means to
present a readable view of the audit data.
OE.I&A The environment allows the Identification and Authentication of an
administrator.
Table 8: Security Objectives for the environment of the TOE
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4.3 Security Objectives Rationale
The following table provides an overview for security objectives coverage. The following chapters
provide a more detailed explanation of this mapping.
OE.ENV
OE.SECINIT
OE.NOEVIL
OE.INFLOW
OE.CONFW
OE.TSP
OE.PROT
OE.AUDIT
OE.I&A
O.FILTER
O.AUDIT
O.MANAGEMENT
A.ENV X
A.SECINIT X
A.NOEVIL X
A.INFLOW X
A.CONFW X
A.TSP X
A.PROT X
A.AUDIT X
A.I&A X
T.BYPASS X X X X X
T.WEAKNESS X X X X X
Table 9: Security Objective Rationale
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4.3.1 Countering the threats
The threat T.BYPASSSS which describes that an attacker may bypass the security functions of the
TOE in order to gain unauthorized access to resources in the protected networks is countered by a
combination of the objectives OE.PROT, OE.ENV, OE.INFLOW, OE.SECINIT and O.FILTER. The
environmental objectives OE.SECINIT, OE.ENV and OE.INFLOW ensure that a user can neither
interfere with the initial setup or the physical setup of the management machine or network
components nor routes around the management machine or network components. Thus, all data
pass through the TOE. O.FILTER ensures that this data is always checked and filtered according to
the policy. Thus, the checked data cannot be modified on its way to gain access to machines in the
protected network. The environmental objective OE.PROT ensures that data flow between the
management machine and the network components is protected by cryptographic transforms, i.e.
that sessions of users already authenticated cannot be taken over.
The threat T.WEAKNESS which describes that an attacker may try to exploit a weakness of the
protocol used in order to read, modify or destroy security sensitive data on the TOE is countered by
a combination of the objectives OE.I&A, O.AUDIT, OE.AUDIT, OE.CONFW and O.MANAGEMENT.
O.AUDIT and OE.AUDIT ensure detection of attempts to compromise the TOE. O.MANAGEMENT
and OE.I&A ensure that only the authorized administrator is able to manage the TSF data and
removes the aspect of the threat where an attacker could try to access sensitive data of the TOE
via its management interface. The environmental objective OE.CONFW ensures that no service
beside SSH run on the network components.
4.3.2 Covering the OSPs
The TOE does not enforce organizational security policies.
4.3.3 Covering the assumptions
The assumption A.ENV is covered by OE.ENV as directly follows.
The assumption A.SECINIT is covered by OE.SECINIT as directly follows.
The assumption A.NOEVIL is covered by OE.NOEVIL as directly follows.
The assumption A.INFLOW is covered by OE.INFLOW as directly follows.
The assumption A.CONFW is covered by OE.CONFW as directly follows.
The assumption A.TSP is covered by OE.TSP as directly follows.
The assumption A.PROT is covered by OE.PROT as directly follows.
The assumption A.AUDIT is covered by OE.AUDIT as directly follows.
The assumption A.I&A is covered by OE.I&A as directly follows.
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5 STATEMENT OF SECURITY REQUIREMENTS
This chapter defines the security functional requirements (see chapter 5.1) and the security
assurance requirements for the TOE (see chapter 5.3). No extended components are defined in
this Security Target (see chapter 5.2).
5.1 Security functional requirements for the TOE
The TOE satisfies the SFRs delineated in the following table. The rest of this chapter contains a
description of each component and any related dependencies.
Security audit (FAU)
FAU_GEN.1 Audit data generation
User data protection (FDP)
FDP_IFC.1 Subset information flow control
FDP_IFF.1 Simple security attributes
User identification (FIA)
FIA_UID.1 Timing of identification
Security management (FMT)
FMT_MSA.1 Management of security attributes
FMT_MSA.3 Static attribute initialisation
FMT_SMF.1 Specification of management functions
FMT_SMR.1 Security roles
Table 10: Security Functional Requirements for the TOE
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5.1.1 Security Audit
5.1.1.1 FAU_GEN.1 Audit data generation
FAU_GEN.1.1 The TSF shall be able to generate an audit record of the
following auditable events:
a) Start-up and shutdown of the audit functions;
b) All auditable events for the [not specified] level of
audit; and
c) [starting of network components; IP datagrams
matching log filters in packet filter rules]
FAU_GEN.1.2 The TSF shall record within each audit record at least the
following information:
a) Date and time of event, type of event, subject
identity (if applicable), and the outcome (success
or failure) of the event;
b) and For each audit event type, based on the
auditable event definitions of the functional
components included in the PP/ST, [no other
audit relevant information]
Hierarchical to: No other components
Dependencies: FPT_STM.1 Reliable time stamps
5.1.2 User data protection (FDP)
5.1.2.1 FDP_IFC.1 Subset information flow control
FDP_IFC.1.1 The TSF shall enforce the [Packet Filter SFP] on
[Subjects: users (external entities) that send and/or
receive information through the TOE to one another;
Information: data sent from one subject through the TOE
to one another;
Operation: pass the data].
Hierarchical to: No other components.
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Dependencies: FDP_IFF.1 Simple security attributes
Application Note: The Packet Filter SFP is given in FDP_IFF. The subject definition in
FDP_IFC.1.1 belongs to a former CC version. Thus the subjects are identical to the users defined
in the external entities definition in chap. 3.3.
5.1.2.2 FDP_IFF.1 Simple security attributes
FDP_IFF.1.1 The TSF shall enforce the [Packet Filter SFP] based on
the following types of subject and information security
attributes:
[Subjects: users (external entities) that send and/or
receive information through the TOE to one another;
Subject security attributes: none;
Information: data sent from one subject through the TOE
to one another;
Information security attributes: source address of subject,
destination address of subject, transport layer protocol,
interface on which the traffic arrives and departs, port,
time].
FDP_IFF.1.2 The TSF shall permit an information flow between a
controlled subject and controlled information via a
controlled operation if the following rules hold: [Subjects
on a network connected to the TOE can cause
information to flow through the TOE to a subject on
another connected network only if all the information
security attribute values are permitted by all information
policy rules].
FDP_IFF.1.3 The TSF shall enforce the [reassembly of fragmented IP
datagrams before inspection].
FDP_IFF.1.4 The TSF shall explicitly authorise an information flow
based on the following rules: [none].
FDP_IFF.1.5 The TSF shall explicitly deny an information flow based
on the following rules:
„ [The TOE shall reject requests of access or services
where the information arrives on a network interface
and the source address of the requesting subject does
not belong to the network associated with the interface
(spoofed packets);
„ The TSF shall drop IP datagrams with the source
routing option;
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„ The TOE shall reject fragmented IP datagrams witch
cannot be reassembled completely within a bounded
interval].
Hierarchical to: No other components.
Dependencies: FDP_IFC.1 Subset information flow control
FMT_MSA.3 Static attribute initialisation
Application Note: The subject definition in FDP_IFF.1.1 belongs to a former CC version. Thus the
subjects are identical to the users defined in the external entities definition in chap. 3.3.
5.1.3 User identification (UID)
5.1.3.1 FIA_UID.1 Timing of identification
FIA_UID.1.1 The TSF shall allow [the following TSF-mediated actions] on behalf
of the user to be performed before the user is identified.
„ all actions except for administrative actions as specified by
FMT_SMF.1
FIA_UID.1.2 The TSF shall require each user to be successfully identified before
allowing any other TSF-mediated actions on behalf of that user.
Hierarchical to: No other components.
Dependencies: No dependencies.
Refinement: The TOE verifies the identification information of an administrator provided by the
environment (see OE.I&A) before any management function can be performed.
Application Note: The “user” in FIA_UID.1.2 is identical to the administrator defined in the external
entities definition in chap. 3.3.
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5.1.4 Security management (FMT)
5.1.4.1 FMT_MSA.1 Management of security attributes
FMT_MSA.1.1 The TSF shall enforce the [Packet Filter SFP] to restrict the ability
to [modify, [no other operations]] the security attributes [network
traffic filter rules and configuration data] to [the role administrator].
Hierarchical to: No other components.
Dependencies: [FDP_ACC.1 Subset access control, or
FDP_IFC.1 Subset information flow control]
FMT_SMR.1 Security roles
FMT_SMF.1 Specification of Management
5.1.4.2 FMT_MSA.3 Static attribute initialization
FMT_MSA.3.1 The TSF shall enforce the [Packet Filter SFP] to provide [restrictive]
default values for security attributes that are used to enforce the
SFP.
FMT_MSA.3.2 The TSF shall allow the [no roles] to specify alternative initial values
to override the default values when an object or information is
created.
Hierarchical to: No other components.
Dependencies: FMT_MSA.1 Management of security attributes
FMT_SMR.1 Security roles
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5.1.4.3 FMT_SMF.1 Specification of management functions
FMT_SMF.1.1 The TSF shall be capable of performing the following management
functions: [
„ Modification of network traffic filter rules,
„ Modification of configuration data].
Hierarchical to: No other components.
Dependencies: No dependencies.
5.1.4.4 FMT_SMR.1 Security roles
FMT_SMR.1.1 The TSF shall maintain the roles [administrator].
FMT_SMR.1.2 The TSF shall be able to associate users with roles.
Hierarchical to: No other components.
Dependencies: FIA_UID.1 Timing of identification
5.2 Extended Components definition
No extended components are defined in this Security Target.
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5.3 Security assurance requirements for the TOE
The following table lists the chosen evaluation assurance components for the TOE.
Assurance Class Assurance Components
ADV ADV_ARC.1, ADV_FSP.4, ADV_IMP.1, ADV_TDS.3
AGD AGD_OPE.1, AGD_PRE.1
ALC ALC_CMC.4, ALC_CMS.4, ALC_DEL.1, ALC_DVS.1
ALC_FLR.2, ALC_LCD.1, ALC_TAT.1
ATE ATE_COV.2, ATE_DPT.2, ATE_FUN.1, ATE_IND.2
AVA AVA_VAN.3
Table 11: Chosen Evaluation Assurance Requirements
These assurance components represent EAL 4 augmented by the component marked in bold text.
The complete text for these requirements can be found in [2].
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5.4 Security Requirements Rationale
5.4.1 TOE functional requirements rationale
O.FILTER
O.AUDIT
O.MANAGEMENT
FAU_GEN.1 X
FIA_UID.1 X
FDP_IFC.1 X
FDP_IFF.1 X
FMT_MSA.1 X
FMT_MSA.3 X
FMT_SMF.1 X
FMT_SMR.1 X
Table 12: Coverage of Security Objective for the TOE by SFR
The security objective O.FILTER is met by a combination of FDP_IFC.1, FDP_IFF.1 and
FMT_MSA.3. FDP_IFC.1 and FDP_IFF.1 describe the information flow controls and information
flow control policy. Together, the SFRs describe how the packet filter information flow policies
apply. FMT_MSA.3 defines that the TOE has to provide restrictive default values for the Packet
Filter SFP (information flow policy) attributes. The SFRs are therefore sufficient to satisfy the
objective O.FILTER and mutually supportive.
The security objective O.AUDIT is met by FAU_GEN.1. FAU_GEN.1 describes when and what kind
of audit data is generated.
The security objective O.MANAGEMENT is met by FMT_SMF.1, FMT_MSA.1, FIA_UID.1 and
FMT_SMR.1. FMT_SMF.1 describes the minimum set of management functionality, which has to
be available. FMT_MSA.1 defines, which roles are allowed to administer the security attributes of
the TOE. FIA_UID.1 requires each user to be identified before allowing any relevant actions on
behalf of that user. Further the objective requires that the TOE will at least maintain the role
administrator. This is defined in FMT_SMR.1, which defines the role.
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5.4.2 Fulfilling the SFR dependencies
The following table shows that all dependencies are met.
SFR Dependencies Fulfilled by
FAU_GEN.1 FPT_STM.1 FPT_STM.1 is satisfied in the IT
environment (see OE.TSP).
FIA_UID.1 No dependencies. -
FDP_IFC.1 FDP_IFF.1 FDP_IFF.1
FDP_IFF.1 FDP_IFC.1 FDP_IFC.1
FMT_MSA.3 FMT_MSA.3
FMT_MSA.1 [FDP_ACC.1or FDP_IFC.1] FDP_IFC.1
FMT_SMR.1 FMT_SMR.1
FMT_SMF.1 FMT_SMF.1
FMT_MSA.3 FMT_MSA.1 FMT_MSA.1
FMT_SMR.1 FMT_SMR.1
FMT_SMF.1 No dependencies. -
FMT_SMR.1 FIA_UID.1 FIA_UID.1
Table 13: Fulfilling the SFR dependencies
5.4.3 Security assurance requirements rationale
The TOE claims compliance to EAL4 level of assurance augmented by ALC_FLR.2. As described
in [2], the level EAL4 indicates that the product is methodically designed, tested, and reviewed.
The assurance requirements for life cycle support have been augmented by ALC_FLR.2 (flaw
reporting procedures) to account for regular bug fixes for the TOE.
This is considered appropriate for attackers with Enhanced-Basic attack potential. The Security
assurance requirements are chosen because of the evaluation level EAL4 according to [2].
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6 TOE SUMMARY SPECIFICATION
6.1 TOE security functionality
6.1.1 SF1 Information Flow Protection
SF1.1 meets FDP_IFC.1, SF1.1, SF1.2 and SF1.3 meet FDP_IFF.1:
SF1.1: The TSF implements the information flow control (as routers) on the network layer (IP) and
transport layer (TCP/UDP/ICMP). In order to define packet filter rules the TSF provides packet filter
criteria and packet filter actions. The packet filter criteria are:
„ source address
„ destination address
„ transport layer protocol
„ interface on which traffic arrives and departs
„ port
„ time
The packet filter actions are:
„ accept (= permit)
„ reject1
(= deny)
„ drop
In order to apply the packet filter rules the network components take the information from the IP and
TCP/UDP/ICMP-Header (where applicable).
SF1.2: The TSF reassembles IP datagrams before further processing is performed. IP datagrams
which cannot be reassembled in a predefined span of time are dropped.
SF1.3: The TSF drops packets with spoofed source- or destination-IP addresses. Packets with
source routing options are also dropped.
6.1.2 SF2 Security Audit
SF2.1 and SF2.2 meet FAU_GEN.1:
SF2.1: The TSF generates audit records for
„ start-up and shutdown of the audit functions
„ datagrams received or sent through a network components network interfaces if they match
configured patterns
1
: reject = drop and signal an error
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SF2.2: Each record includes:
„ Time and Date
„ Affected network component
„ Subject identity (source IP)
„ Type of event
„ Affected Interface
„ Direction
„ Action (accept, drop or reject)
„ Optional depending on the protocol: IP addresses and ports
6.1.3 SF3 Management
SF3.1 meets FMT_SMF.1. SF3.2 meets FIA_UID.1, FMT_MSA.1 and FMT_SMR. SF3.3 meets
FMT_MSA.3.
SF3.1: The TSF is capable of performing the following management functions:
„ Modification of network traffic filter rules,
„ Modification of configuration data,
SF3.2: In order to modify the security attributes network traffic filter rules and configuration data the
TOE maintains the role administrator. The TOE verifies the identification information of an
administrator provided by the environment (see OE.I&A) before any management function can be
performed. Therefore the TOE verifies if the user id is equal to zero.
SF3.3: The TOE is initialized with a strict packet filter rule set, i. e. everything is dropped.
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7 GLOSSARY AND ACRONYMS
Definition
AES Advanced Encryption Standard
BSI Bundesamt für Sicherheit in der Informationstechnik
LAN Local Area Network
NTP Network Time Protocol
PP Protection Profile
SFP Security Function Policy
SFR Security Functional Requirement
SSH Secure Shell
ST Security Target
TOE Target of Evaluation
TSF TOE Security Function
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8 REFERENCES
Common Criteria
[1] Common Criteria for Information Technology Security Evaluation, Part 2: Security
Functional Components; Version 3.1, Revision 2, CCMB-2006-09-002
[2] Common Criteria for Information Technology Security Evaluation, Part 3: Security
Assurance Components; Version 3.1, Revision 2, CCMB-2006-09-003
Cryptography
[3] RFC4253, SSH Transport Layer Protocol, http://www.ietf.org/rfc/rfc4253.txt
[4] RFC 791, Internet Protocol, http://www.ietf.org/rfc/rfc791.txt
Documentation
[5] secunet wall packet filter, documentation