Public
SECURITY TARGET – ZOOM APPLICATION
ZOOM VIDEO COMMUNICATIONS, INC.
Version:
1.8
Date:
15/12/2021
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SECURITY TARGET – ZOOM APPLICATION
PREPARED BY
IDENTIFICATION OF SERVICE PROVIDER
Organization Name Zoom Video Communications, Inc.
Street Address 55 Almaden Boulevard
Suite/Room/Building 6th
Floor
City, State Zip San Jose, CA 95113
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TABLE OF CONTENTS
Introduction ...................................................................................................................................................5
ST-Reference .............................................................................................................................................5
TOE Reference...........................................................................................................................................5
TOE Overview............................................................................................................................................6
Licensing Information ............................................................................................................................9
Required Non-TOE hardware and software .........................................................................................9
TOE description .......................................................................................................................................10
Physical Scope.....................................................................................................................................10
Logical Scope.......................................................................................................................................11
Zoom Meetings....................................................................................................................................11
Zoom Chat............................................................................................................................................11
Security Features .................................................................................................................................11
Conformance Claims...................................................................................................................................13
Common Criteria Conformance Claim ...................................................................................................13
Protection Profile Conformance Claim ...................................................................................................13
Conformance Rationale...........................................................................................................................13
Security Problem Definition........................................................................................................................14
Assets.......................................................................................................................................................14
Threats .....................................................................................................................................................15
Organizational Security Policies .............................................................................................................15
Assumptions............................................................................................................................................15
Security Objectives .....................................................................................................................................17
Security Objectives for the TOE .............................................................................................................17
Security Objectives for the TOE-environment .......................................................................................17
Security Objectives Rationale .................................................................................................................19
T.Access_Meeting................................................................................................................................19
T.Access_Login ....................................................................................................................................19
T.Network.............................................................................................................................................20
T.Bypass_User_Controls......................................................................................................................20
T.Access_Stored_Data.........................................................................................................................20
OSP.Meeting_Password_Policy ..........................................................................................................20
A.Meeting_Key.....................................................................................................................................20
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A.User_Credentials ..............................................................................................................................20
A.Rate_Limiting ....................................................................................................................................20
A.Secure_Backend...............................................................................................................................20
A.Host_Device......................................................................................................................................20
A.Managed_Device..............................................................................................................................21
A.Proper_User......................................................................................................................................21
A.Non_Hostile_Platform ......................................................................................................................21
Extended Components Definition ..............................................................................................................22
Cryptographic key import (FCS_CKM_EXT.1)........................................................................................22
Family Behaviour .................................................................................................................................22
Component levelling............................................................................................................................22
Management FCS_CKM_EXT.1...........................................................................................................22
Audit FCS_CKM_EXT.1........................................................................................................................22
FCS_CKM_EXT.1 Cryptographic key import ..................................................................................22
Security Requirements ...............................................................................................................................23
Policies .....................................................................................................................................................23
User Control policy ..............................................................................................................................23
SFRs .........................................................................................................................................................23
Identification and authentication.........................................................................................................23
Access Control .....................................................................................................................................24
Cryptographic operations - General....................................................................................................26
Cryptographic operations – Zoom Meetings......................................................................................28
Cryptographic operations – Zoom Chat .............................................................................................28
SARs.........................................................................................................................................................31
Security Requirements Rationale ...........................................................................................................31
Dependency Rationale.........................................................................................................................31
Security functional requirements rationale ........................................................................................32
Security assurance requirements rationale........................................................................................34
TOE Summary Specification ......................................................................................................................35
User identification and authentication....................................................................................................35
Meeting authentication............................................................................................................................35
User and security controls ......................................................................................................................35
Secure data transfer ................................................................................................................................35
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Zoom Chat ...............................................................................................................................................35
Use of Cryptographic Functions.................................................................................................................36
Annex...........................................................................................................................................................37
Reference Documentation ......................................................................................................................37
Terminology.............................................................................................................................................39
List of figures ...........................................................................................................................................39
List of tables.............................................................................................................................................39
INTRODUCTION
ST-REFERENCE
Sponsor: Zoom Sales Team International
Developer: Zoom Video Communications INC.
ST Version: 1.8
Date: 15-12-2021
CC Version: 3.1 Revision 5
Assurance Level: EAL 2
Certification ID: BSI-DSZ-CC-1173
TOE REFERENCE
TOE Name: Zoom Application
Table 1: TOE-Versions of the different clients
Client Version
Windows-Client (64-Bit) 5.6.6
macOS-Client (Intel architecture) 5.6.6
Android-Client 5.6.6
iOS/iPadOS-Client 5.6.6
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TOE OVERVIEW
The TOE is a multi-platform software application used to host, run and organize enterprise web
video communications (web meetings), with an easy, reliable cloud platform (Zoom Backend) for video and
audio conferencing, collaboration, chat across mobile devices and desktops. The Zoom Backend is not part
of the TOE, but of its environment.
Web meetings are primarily used to offer audio and video conferencing as well as desktop sharing.
Additionally, during web meetings a user can share files and text messages with the other participants.
To access a web meeting, participants must know a randomly generated Meeting-ID as well as the meeting
password set by the meeting’s host. All communication between the TOE and the Zoom backend is
protected by either TLS or Zoom’s meeting encryption. For meeting encryption, the traffic of all meeting
participants is encrypted using a symmetric meeting key generated by the Zoom backend. During a meeting,
the meeting host, and if present the meeting co-host have access to certain security controls, e.g. admit
participant to the meeting room, muting all participants but themselves, allowing or prohibiting screen
sharing and recordings. Those controls are set by the respective users using the TOE but can only be
enforced on server-side. Meeting participants can also access controls of their own, like muting themselves,
starting screen share or enabling their video stream. The controls and their associated actions are protected
by a role-based access control mechanism enforced by the TOE.
Figure 1 below shows the default view of a meeting participant:
Figure 1: Default participant view
For a meeting host, there is more functionality available as shown in Figure 2:
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Figure 2: Host view during a meeting
As can be seen in Figure 2, the TOE provides the meeting host with additional settings under the tab
“Security”. Those security settings provide the meeting host and co-host the possibility to
• Lock meeting
• Enable waiting rooms
• Allow participants to:
▪ Share screen
▪ Chat
▪ Rename themselves
▪ Unmute themselves
▪ Start video
The TOE also offers an out-of-meeting instant messaging service called Zoom Chat, which can be used to
share text, audio and video messages with one or more TOE users outside of web meetings. It is also
possible share files with other users outside of web meetings by uploading them to Zoom Chat.
The Zoom Chat requires the TOE to keep contact and channel lists as part of the user data. The data is
stored on the TOE’s host device, an additional copy is also stored on the Zoom backend. As described
before, the transport of the data from Zoom backend to the TOE is secured by TLS. Additionally, the TOE
requires user authentication by username and password (with enforced password limitations) and also offers
use of Multi-factor authentication. Messaging data (text and audio messages) is stored on the TOE’s host
device in an encrypted database. Additionally, for backup reasons, each encrypted message that is sent or
received by the TOE is also stored on the Zoom backend using AWS Server Side Encryption (SSE)1.
Figure 3 shows the default view for Zoom Chat:
1
https://docs.aws.amazon.com/AmazonS3/latest/dev/serv-side-encryption.html
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Figure 3: Default view for Zoom Chat
The diagram in Figure 4 provides a high-level overview of the main components acting in a Zoom meeting
communication.
Figure 4: Overview of main components
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Note that “Client B” is not described as detailed as “Client A” to simplify the image. They are both TOE
instances.
The TOEs main security features are as follows:
• Secure user authentication,
• Protection of confidentiality and integrity of all data transferred during Zoom Meetings,
• Enforcing access control rules during Zoom Meetings, e.g. prohibiting users from unmuting their
microphone,
• Enforcing of user controls, e.g. making sure no audio data is transferred if a user mutes his
microphone during a Zoom Meeting,
• Protection of integrity and confidentiality of all data exchanged during Zoom Chats, including
protection from Zoom itself by offering optional end-to-end encryption for Zoom Chats,
• Protection of Zoom Chat data (e.g. chat messages, voice notes) stored on the user’s device.
The TOE can be run on the following platforms:
Table 2: Supported Environments
Operating System Supported Environment
Microsoft Windows Windows 10 Home, 10 Pro and 10 Enterprise
Apple macOS macOS 10.13 (Sierra), 10.14 (Mojave), 10.15
(Catalina), 11 (Big Sur)
Apple iOS/iPadOS iOS 12, 13 and 14, iPadOS 13 and 14
Android Android 8.1, 9, 10 and 11
Note that a Linux version of the TOE is also available. However, this version is not in scope for the
certification at this time and will therefore not be discussed in the following sections.
Licensing Information
The Zoom Application can be operated with a free and a paid licence. The certified version (the TOE) needs
to be operated with a paid license. The binary of the Zoom application is the same for both licensing models,
the only technical difference in terms of security is, that users with a free license cannot initiate end-to-end
encrypted Zoom Chats, they can however still participate in end-to-end encrypted chats if a user with a paid
license initiated the chat.
All threats addressed by the TOE can also be mitigated with the free licensing, paid licencing only offers an
additional layer of security for Zoom Chat.
Required Non-TOE hardware and software
The TOE needs to run on either a computer running Windows or macOS or a mobile device running Android
or iOS/iPadOS. To perform cryptographic operations the TOE makes use of OpenSSL version 1.1.
All devices the Zoom application is installed on need to be part of a managed client infrastructure that
controls which applications can be installed on the device
The TOE also requires the Zoom backend to operate.
For Android devices it is required that
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1) The TOE is run in a managed environment, i.e:
a) the device supports an enterprise container technology (e.g. Android for Work2, Samsung Knox)
and the TOE is only run in a managed work profile, or
b) the TOE is run on an exclusive, managed enterprise device,
2) the device makes use of an embedded security module
The following devices (Table 3) are in scope for this certification. The devices are taken from the list of
devices that Google labelled as “android enterprise recommended”3. Devices on this list need to provide
regular security updates to the user. Also, being on that list grants a higher level of assurance that the used
Android version has not been altered by the vendor compared to Google’s version.
Table 3: Supported Android mobile devices
Vendor Model Secure Element
Xiaomi Xiaomi Mi 10T Pro Qualcomm Secure
Processing Unit
Google Google Pixel 4XL Titan M Chip
TOE DESCRIPTION
Physical Scope
The TOE is a software application expected to run on a Windows or macOS computer or an Android or iOS
device. The TOE as a software application does not have any physical boundaries. The complete TOE in
terms of the Common Criteria includes:
• the software application, in form of an executable program, delivered as described in Table 4,
• an operational manual, available as a download from Zoom’s website4 in form of a PDF file [AGD].
Since there are four different platforms, there are also four TOE configurations. Each configuration consists
of the TOE installed on the respective platform.
Table 4: Delivery overview for the different platforms
Platform Way of delivery
Microsoft Windows [TOE-Windows] Download from Zoom’s website
Apple macOS [TOE-Mac] Download from Zoom’s website
Android [TOE-Android] Download from Zoom’s website or Google
Play Store
Apple iOS/iPadOS [TOE-ios] iOS App Store
2
https://www.android.com/enterprise/
3
https://androidenterprisepartners.withgoogle.com/devices/#!?device_categories=knowledge_worker&region_na
mes=europe
4
https://zoom.us/
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Logical Scope
The TOE only includes the Zoom Meeting and Zoom Chat functionality of the Zoom application. The Zoom
backend is explicitly not part of the TOE.
Admin management is not part of the Zoom application and therefore not TOE functionality.
The enforcement of security controls is done by the Zoom application. The enforcement settings are set by
the meeting host (in the Zoom application) and then stored server-side. The security controls to enforce are
received from server-side.
Random number generation for cryptographic operations is left to the TOE’s environment.
Zoom Meetings
Zoom Meetings are the main feature of the TOE. They are primarily used to offer
audio and video conferencing as well as desktop sharing. Additionally, during web meetings a user can
share files and text messages with the other participants.
To access a meeting, users authenticate themselves to the Zoom backend and then the TOE connects to
a Multimedia Router (MMR). The MMR is the TOE’s main communication partner during meetings and
assigns each user one of three roles: Host, Co-Host or Participant.
The Host is usually the user who scheduled the meeting, while Co-Hosts are participants that the Host wants
to give Host-Controls to. Host-Controls include the ability to decide which users are able to talk, show their
camera or screen and record the meeting. Additionally, Host and Co-Hosts have access to the “Security
Option” of a meeting (see Figure 2). Please note, that the functionalities
• Lock Meeting,
• Enable Waiting Room,
• Hide Profile Pictures,
• Chat and
• Rename themselves
are not security features in the sense of this certification, but out-of-scope features of the Zoom Client.
Zoom Chat
Zoom Chat is an out-of-meeting instant messaging service, which can be used to share text, audio and
video messages with one or more TOE users outside of web meetings.
All Chats are by default TLS encrypted. The TOE also stores chat messages in a local database that is
encrypted and integrity protected. Additionally, user can enable Advanced Chat Encryption (ACE) which
provides end-to-end encrypted chats. If activated, the TOE performs a key agreement with the receiving
user and encrypts the message making use of a shared secret. Chats using ACE are still TLS protected
during transfer. Zoom Chat uses the XMPP protocol to transmit messages between users through the Zoom
backend.
Security Features
• Authentication
The TOE supports password-based authentication with the option to enable Two-Factor
authentication using time-based one-time passwords.
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• Protection of confidentiality and integrity during Zoom Meetings
All meeting data transferred during Zoom Meetings is encrypted using AES256-GCM using a
symmetric key generated and distributed by the Zoom backend. All other communication between
the TOE and Zoom backend is protected by TLS 1.2 or TLS 1.3.
• Enforcing of access control rules during Zoom Meetings
The TOE maintains the current meeting security attributes, i.e. a list of permissions the user has.
The meeting security attributes can be manipulated by the Host and Co-Host of a meeting. Changes
of the meeting security attributes are sent by the Host (or Co-Host) to the MMR in the Zoom
Backend. From there the updated list of permissions is distributed to each user. For each user
action covered by the meeting security attributes, the TOE checks if the user is permitted to perform
said action. If not, the action is cancelled by the TOE. Additionally, UI elements are greyed out if
the user is not permitted to perform the associated action.
• Enforcing of user controls during a Zoom Meeting
Similarly to the methods described above, the TOE also keeps a list of the user’s settings (User
Controls) during a meeting. Every time the TOE captures input data from e.g. the microphone, it
checks, if the user has their microphone enabled or disabled. If the microphone is disabled, the
input data is dismissed and not sent to the MMR. The same applies for video and screen share.
• Protection of integrity and confidentiality during Zoom Chats
Messages exchanged between users using Zoom Chat are always protected by TLS. Additionally,
users can choose to make use of Advanced Chat Encryption which enables end-to-end encryption
in Zoom Chats. In this case the users participating in the Zoom Chat perform a Diffie-Hellman key
agreement using long-term elliptic curve keys created during TOE installation to derive a shared
secret key. The necessary public keys are stored in the Zoom backend. This key is then used to
encrypt messages using AES256-CBC encryption.
• Protection of Zoom Chat data stored on the user’s device
Every message sent and received through Zoom Chats is stored in a local database. The database
is encrypted using ASE256-CBC and integrity protected using HMAC-SHA512. The keys used for
encryption and integrity protection are securely stored using OS functionality.
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CONFORMANCE CLAIMS
COMMON CRITERIA CONFORMANCE CLAIM
This Security Target claims conformance to:
• Common Criteria for Information Technology Security Evaluation, Part 1: Introduction and General
Model; CCMB-2017-04-001, Version 3.1, Revision 5, April 2017 [CC1]
• Common Criteria for Information Technology Security Evaluation, Part 2: Security Functional
Components; CCMB-2017-04-002, Version 3.1, Revision 5, April 2017 [CC2]
• Common Criteria for Information Technology Security Evaluation, Part 3: Security Assurance
Components; CCMB-2017-04-003, Version 3.1, Revision 5, April 2017 [CC3]
as follows:
• CC Part 2 extended
• CC Part 3 conformant (EAL 2)
PROTECTION PROFILE CONFORMANCE CLAIM
This Security Target does not claim conformance to any Protection Profile.
CONFORMANCE RATIONALE
This ST claims conformance to CC Part 2 extended because it uses the extended component
“Cryptographic key import (FCS_CKM_EXT.1)”. All other SFRs are from CC Part 2 [CC2].
The ST also claims conformance to CC Part 3 as all SARs are from the EAL package EAL2 defined in CC
Part 3 [CC3].
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SECURITY PROBLEM DEFINITION
ASSETS
Table 5: Assets
ID Description
SA.User_Credentials The credentials a TOE user uses to access his
account, i.e. username and password.
SA.User_Data A TOE user’s associated data, e.g. e-mail, name,
license information, contact lists, billing information
and user profile info (i.e. first name, last name,
profile picture, department, language preferences, IP
address, location).
SA.Meeting_Credentials The credentials a TOE user uses to access a
meeting. These are the Meeting-ID and password.
SA.Meeting_Data The data transferred between a TOE user and the
Zoom backend during a meeting, e.g. voice streams,
video/camera streams, shared screen, chats, file
shared during a meeting.
SA.Meeting_Meta_Data The meta data transferred between a TOE user and
the Zoom backend during a meeting used for
troubleshooting and statistics purposes such as
active users, meetings duration, network type (e.g.
Wi-Fi, LAN).
Zoom Quality-of-Service (QoS) reports for past
Zoom meetings collect the following information:
device type, OS type and version, CPU memory,
graphics card, device display info, network type,
microphone, speaker selected, camera selected.
SA.Meeting_Key The key used to encrypt communication during a
meeting.
SA.Meeting_Data_To_Backend Meeting data that is to be stored in the backend, e.g.
chat messages, shared files, meeting recordings.
SA.User_Controls The meeting controls chosen by a meeting
participant, e.g. audio mute, video/screen shared.
SA.Zoom_Chat_Data The data transferred between a TOE user and the
Zoom backend during Zoom Chat such as text
messages, voice and video recordings.
SA.Stored_Zoom_Chat_Data Zoom Chat data stored on TOE’s host device. This
data includes text messages as well as video and
voice recordings.
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THREATS
Table 6: Threats
ID Description
T.Access_Login An attacker bypasses the security functions of the TOE to
gain unauthorized access to SA.User_Data and
SA.User_Credentials.
T.Access_Meeting An attacker gains access to a Zoom meeting that he is not
authorized to join, therefore gaining access to
SA.Meeting_Data, SA.Meeting_Credentials or
SA.Meeting_Key.
T.Network An attacker hijacks the communication between the Zoom
backend and the TOE and manipulates or gains access to
SA.Meeting_Data, SA.Meeting_Data_To_Backend,
SA.Meeting_Meta_Data, SA.Meeting_Key,
SA.Zoom_Chat_Data.
T.Bypass_User_Controls A meeting participant gains access to shared audio, camera
or screen share data, even though SA.User_Controls is set to
not share that data.
T.Access_Stored_Data An attacker gains access to the TOE’s host device and
accesses SA.Stored_Zoom_Chat_Data.
ORGANIZATIONAL SECURITY POLICIES
Table 7: Organizational Security Policies
ID Description
OSP.Meeting_Password_Policy Meeting Hosts shall not choose weaker meeting
passwords than the randomly generated one (initial
password).
ASSUMPTIONS
Table 8: Assumptions
ID Description
A.Meeting_Key The Zoom backend generates SA.Meeting_Key and
provides at least 120 bit security.
A.User_Credentials Any user of the TOE does not disclose their authentication
or meeting credentials to any individual not authorized for
access to the TOE or meeting.
A.Rate_Limiting The Zoom backend implements rate limiting on brute-
force-attacks for meeting password and user
authentication.
A.Secure_Backend The Zoom backend is trusted. Data sent from the Zoom
backend is assumed to be with integrity.
A.Host_Device The TOE’s host device of the TOE offers means to
securely store and access cryptographic keys, as well as
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provide a random number generator of appropriate
strength to be used for cryptographic operations required
by the TOE.
A.Managed_Device The TOE runs on a managed device. The device
management controls which applications can be installed
on the device, to ensure no malicious applications are
installed which could harm the security of the TOE.
For Android smartphones this means, the device has to
support an enterprise container technology, and the TOE
runs in a work profile or on an exclusive, managed
enterprise device.
A.Proper_User The user of the application is not wilfully negligent or
hostile and uses the TOE within compliance of the
applied enterprise security policy.
A.Non_Hostile_Platform The platform on which the TOE is running on does not
start any attacks on assets protected by the TOE.
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SECURITY OBJECTIVES
SECURITY OBJECTIVES FOR THE TOE
Table 9: Security Objectives for the TOE
ID Description
O.Secure_Channel The connection between the TOE and the Zoom
backend shall provide a secure trusted channel so that
confidentiality and integrity of all information transmitted
when the user accesses through the TOE are protected.
O.Meeting_Encryption The TOE shall provide strong encryption for all data
transmitted during a meeting using SA.Meeting_Key.
O.Secure_Storage The TOE shall ensure Zoom Chat data stored on the
TOE’s host device is never stored in plain text.
O.Meeting_Authentication The TOE shall ensure only authorized users can access
a meeting.
O.Authentication The TOE shall ensure only authenticated users can
access user data.
O.User_Control The TOE shall enforce the SA.User_Controls set for
each meeting participant.
O.User_Control_Remote The TOE shall implement access control, so users can
only use the controls according to the meeting security
attributes.
O.Advanced_Chat_Encryption The TOE shall implement end-to-end encrypted chats
between members of the same organization.
SECURITY OBJECTIVES FOR THE TOE-ENVIRONMENT
Table 10: Security Objectives for the TOE-environment
ID Description
OE.Meeting_Password_Policy Users of the TOE shall not weaken the automatically
generated password when creating a meeting.
OE.Keys The Zoom backend shall generate SA.Meeting_Key and
provide at least 120 bit security.
OE.User_Credentials Users of the TOE shall not disclose their authentication or
meeting credentials to any individual not authorized for
access to the TOE or meeting.
OE.Rate_Limiting The Zoom backend shall implement rate limiting after a
certain amount of failed authentication attempts for either
user or meeting authentication.
OE.Secure_Key_Storage The host device of the TOE shall provide means to
securely store and access cryptographic keys.
OE.Meeting_Security_Attributes The Zoom backend shall store, protect the integrity and
update meeting security attributes for authenticated
meeting hosts. Meeting security attributes include
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ID Description
permissions of participants (e.g. who is allowed to share
their screen) as well as the user identification who is
meeting host.
OE.Meeting_Security_Controls The Zoom backend shall enforce the security controls set
by meeting Host and Co-Host.
OE.Password_Strength The Zoom backend shall ensure that user selected
passwords are complex.
OE.Managed_Device The organization using the TOE shall make sure the TOE
is only installed on managed devices. The client
management shall ensure no malicious applications are
installed on the device.
OE.Proper_User The user of the application shall not be wilfully negligent or
hostile and use the TOE within compliance of the applied
enterprise security policy.
OE.Secure_Server_Storage The Zoom backend shall protect the confidentiality and
integrity of all data sent to be stored in it.
OE.RNG The host device shall provide a random number
generator of appropriate strength to be used for
cryptographic purposes required by the TOE.
Note: Due to the multitude of supported platforms,
users of the TOE are able to choose which platform
(including its RNG) they use.
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SECURITY OBJECTIVES RATIONALE
Table 11: Security Objectives Rationale
T.Access_Meeting
O.Meeting_Authentication ensures meetings can only be accessed by entering the correct Meeting-ID
and Meeting-Password. O.Secure_Channel prevents attackers from gaining access to that information by
listening into the communication. The Secure Channel is supported by OE.RNG for generation of random
numbers. OE.User_Credentials prevents users from sharing meeting credentials with any user not meant
to take part in the meeting. OE.Rate_Limiting hinders the performance of a brute-force-attack on the
meeting password. The attack vector is further weakened by OE.Meeting_Password_Policy which
prevents use of weak meeting passwords.
T.Access_Login
O.Secure_Channel
O.Meeting_Encryption
O.Secure_Storage
O.Meeting_Authentication
O.Authentication
O.User_Control
O.User_Control_Remote
O.Advanced_Chat_Encryption
OE.Meeting_Password_Policy
OE.Keys
OE.User_Credentials
OE.Rate_Limiting
OE.Secure_Key_Storage
OE.Meeting_Security_Attributes
OE.Meeting_Security_Controls
OE.Password_Strength
OE.Managed_Device
OE.Proper_User
OE.Secure_Server_Storage
OE.RNG
T.Access_Meeting x x x x x x
T.Access_Login x x x x x x
T.Network x x x x x x
T.Bypass_User_Controls x x x
T.Access_Stored_Data x x x x
OSP.Meeting_Password_
Policy
x
A.Meeting_Key x
A.User_Credentials x
A.Rate_Limiting x
A.Secure_Backend x x x
A.Host_Device x x
A.Managed_Device x
A.Proper_User x
A.Non_Hostile_Platform x
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O.Authentication enforces authentication of users by at least username and password. Optionally
authentication can be strengthened by use of multi-factor-authentication. OE.Password_Strength requires
the used password to be cryptographically strong to prevent password guessing attacks.
O.Secure_Channel ensure passwords are only transferred to the Zoom backend in encrypted form, to
prevent potential Man-in-the-Middle attacks. The Secure Channel is supported by OE.RNG for generation
of random numbers. OE.User_Credentials prevents users from sharing their user credentials with any other
person. OE.Rate_Limiting weakens brute-force attacks.
T.Network
O.Secure_Channel requires all communication between TOE and Zoom backend to be encrypted and
integrity-protected. During meetings an additional layer of encryption is used (O.Meeting_Encryption).
That encryption is possible due to the secure server-generated key (OE.Keys). Zoom Chat is encrypted
using the O.Secure_Channel. As an additional layer of protection Advanced Chat Encryption can be
enabled (O.Advanced_Chat_Encryption). The key generation for Advanced Chat Encryption and the
secure channel is supported by OE.RNG. OE.Managed_Device ensures only trusted software is installed
on the TOE’s host device that won’t try to access data in the communication channel.
T.Bypass_User_Controls
O.User_Control_Remote enforces access controls during a meeting according to the meeting security
attributes managed by OE.Meeting_Security_Attributes. O.User_Control enforces the controls set by the
participant.
T.Access_Stored_Data
O.Secure_Storage makes sure data is only stored on the TOE’s host device in encrypted form. The key
used to encrypt the data is generated with the help of OE.RNG. Key storage is done with
OE.Secure_Key_Storage. OE.Managed_Device ensures only trusted software is installed on the TOE’s
host device that won’t try to access data stored on the device.
OSP.Meeting_Password_Policy
OE.Meeting_Password_Policy makes sure users chose meeting passwords that are not weaker
compared to the automatically generated (initial) meeting passwords.
A.Meeting_Key
A.Meeting_Key is met by the equally named OE.Keys.
A.User_Credentials
A.User_Credentials is met by the equally named OE.User_Credentials.
A.Rate_Limiting
A.Rate_Limiting is met by the equally named OE.Rate_Limiting.
A.Secure_Backend
A.Secure_Backend requires the Zoom backend to be trusted and to protect the data stored on it. This is
achieved by OE.Secure_Server_Storage. Additionally, both OE.Meeting_Security_Attributes and
OE.Meeting_Security_Controls protect the meeting security attributes.
A.Host_Device
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A.Host_Device requires the TOE’s host device to provide means to securely store and access
cryptographic keys. This is achieved by OE.Secure_Key_Storage. It also requires the host device to
provide a random number generator of appropriate strength to be used for cryptographic operations. This
is fulfilled by OE.RNG.
A.Managed_Device
A.Managed_Device is met by the equally named OE.Managed_Device.
A.Proper_User
A.Proper_User is met by the equally named OE.Proper_User.
A.Non_Hostile_Platform
By providing a managed runtime environment for the TOE, OE.Managed_Device also ensures the platform
is not hostile as required by A.Non_Hostile_Platform.
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EXTENDED COMPONENTS DEFINITION
CRYPTOGRAPHIC KEY IMPORT (FCS_CKM_EXT.1)
Family Behaviour
The family FCS_CKM_EXT is an enhancement of FCS_CKM defined in CC Part 2 [CC2]. It describes rules
for key import. Key import is the process by which one or more keys are generated on a trusted, non-TOE
platform and imported to the TOE over a trusted channel.
Component levelling
The family FCS_CKM_EXT.1 only contains one component FCS_CKM_EXT.1.
Management FCS_CKM_EXT.1
There are no management activities foreseen.
Audit FCS_CKM_EXT.1
There are no audit activities foreseen.
FCS_CKM_EXT.1 Cryptographic key import
Hierarchical to: No other components
Dependencies: FCS_CKM.4 Cryptographic key destruction
FCS_COP.1 Cryptographic operation
[FTP_ITC.1 Inter-TSF trusted channel or
FTP_TRP.1 Trusted path]
FCS_CKM_EXT.1.1 The TSF shall import cryptographic keys from another trusted IT-entity which can
be used for [assignment: cryptographic operation].
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SECURITY REQUIREMENTS
POLICIES
User Control policy
The User Control Policy is defined as:
1 Purpose: To control access to user controls during a meeting
2 Subjects: Participants of a meeting
3 Information: User controls (SA.User_Controls)
4 Security attributes: State of the control, i.e. enabled or disabled
5 SFR instances: FDP_ACC.1/UC, FDP_ACF.1/UC
SFRS
Identification and authentication
FIA_UID.1 Timing of identification
Hierarchical to: No other components
Dependencies: No dependencies.
FIA_UID.1.1 The TSF shall allow accessing and changing general settings, including setting the defaults
for activated camera and audio during meetings5 on behalf of the user to be performed
before the user is identified.
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.
FIA_UAU.1/Client Timing of identification
Hierarchical to: No other components
Dependencies: FIA_UID.1 Timing of identification
FIA_UAU.1.1/Client The TSF shall allow accessing and changing general settings, including setting the
defaults for activated camera and audio during meetings6 on behalf of the user to
be performed before the user is authenticated.
FIA_UAU.1.2/Client The TSF shall require each user to be successfully authenticated before allowing
any other TSF-mediated actions on behalf of that user.
ST application note 1: This SFR applies to user authentication to the TOE
5
[assignment: list of TSF-mediated actions]
6
[assignment: list of TSF-mediated actions]
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FIA_UAU.2/Meeting User authentication before any action
Hierarchical to: FIA_UAU.1 Timing of authentication
Dependencies: FIA_UID.1 Timing of identification
FIA_UAU.2.1/Meeting The TSF shall require each user to be successfully authenticated before allowing
any other TSF-mediated actions on behalf of that user.
ST application note 2: This SFR applies to user authentication to a meeting. To authenticate a
user needs both the Meeting-ID and the password set by the meeting Host. In addition to entering
this data in the Zoom Client users can join meetings by using a meeting invite link or by
accepting a meeting invitation in the Zoom client. Both ways contain the Meeting ID and
password in an encoded format.
FIA_UAU.5 Multiple authentication mechanisms
Hierarchical to: No other components.
Dependencies: No dependencies.
FIA_UAU.5.1 The TSF shall provide password-based authentication, Time-based one-time passwords7
to support user authentication.
FIA_UAU.5.2 The TSF shall authenticate any user's claimed identity according to the following rules:
1) Password-based authentication,
2) Authentication with time-based one-time passwords can be enabled by TOE users
as a second factor in case of password-based authentication.8
Access Control
FDP_ACC.1/UC Subset access control
Hierarchical to: No other components.
Dependencies: FDP_ACF.1 Security attribute based access control
FDP_ACC.1.1/UC The TSF shall enforce the User Control Policy9 on
1 subjects: Participants;
2 objects: SA.User_Controls;
3 operations: Enabling/Disabling of user controls10.
FDP_ACF.1/UC Security attribute based access control
Hierarchical to: No other components.
Dependencies: FDP_ACC.1 Subset access control
7
[assignment: list of multiple authentication mechanisms]
8
[assignment: rules describing how the multiple authentication mechanisms provide authentication]
9
[assignment: access control SFP]
10
[assignment: list of subjects, objects, and operations among subjects and objects covered by the SFP]
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FMT_MSA.3 Static attribute initialisation
FDP_ACF.1.1/UC The TSF shall enforce the User Control Policy11 to objects based on the following:
1 subjects: Participants;
2 objects: SA.User_Controls12.
FDP_ACF.1.2/UC The TSF shall enforce the following rules to determine if an operation among
controlled subjects and controlled objects is allowed: The right to enable or disable
user controls is given according to the meeting security attributes13.
FDP_ACF.1.3/UC The TSF shall explicitly authorise access of subjects to objects based on the
following additional rules: The Host of a meeting has full access and can
enable/disable his own user controls without limitations14.
FDP_ACF.1.4/UC The TSF shall explicitly deny access of subjects to objects based on the following
additional rules: none15.
FMT_MSA.3/UC Static attribute initialisation
Hierarchical to: No other components.
Dependencies: FMT_MSA.1 Management of security attributes
FMT_SMR.1 Security roles
FMT_MSA.3.1/UC The TSF shall enforce the User Control Policy16 to provide permissive17 default
values for security attributes that are used to enforce the SFP.
FMT_MSA.3.2/UC The TSF shall allow the Host18 to specify alternative initial values to override the
default values when an object or information is created.
ST application note 3: Initial values in this context means the initial values during a meeting. E.g.
a host can mute all participants when they join, and can prevent them from unmuting themselves.
FMT_MSA.1 Management of security attributes
Hierarchical to: No other components.
Dependencies: [FDP_ACC.1 Subset access control, or
11
[assignment: access control SFP]
12
[assignment: list of subjects and objects controlled under the indicated SFP, and for each, the SFP-relevant
security attributes, or named groups of SFP-relevant security attributes]
13
[assignment: rules governing access among controlled subjects and controlled objects using controlled
operations on controlled objects]
14
[assignment: rules, based on security attributes, that explicitly authorise access of subjects to objects]
15
[assignment: rules, based on security attributes, that explicitly deny access of subjects to objects]
16
[assignment: access control SFP, information flow control SFP]
17
[selection, choose one of: restrictive, permissive, [assignment: other property]]
18
[assignment: the authorised identified roles]
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FDP_IFC.1 Subset information flow control]
FMT_SMR.1 Security roles
FMT_SMF.1 Specification of Management Functions
FMT_MSA.1.1 The TSF shall enforce the User control policy19 to restrict the ability to change_default20 the
security attributes SA.User_Controls21 to Host22.
FMT_SMR.1 Security roles
Hierarchical to: No other components.
Dependencies: FIA_UID.1 Timing of identification
FMT_SMR.1.1 The TSF shall maintain the roles Authenticated User, Non-Authenticated User, Host, Co-
Host, Participant23.
FMT_SMR.1.2 The TSF shall be able to associate users with roles.
ST application note 4: The roles Host, Co-Host and Participant are the roles TOE users get
assigned during a meeting. The roles Non-Authenticated User and Authenticated User are roles a
TOE user can have in respect to the TOE
FMT_SMF.1 Specification of Management Functions
Hierarchical to: No other components.
Dependencies: No dependencies.
FMT_SMF.1.1 The TSF shall be capable of performing the following management functions:
• Mute/Unmute microphone,
• Enable/Disable camera,
• Enable/Disable screen sharing,
• Enable/Disable meeting recording24.
Cryptographic operations - General
FTP_ITC.1 Inter-TSF trusted channel
Hierarchical to: No other components.
Dependencies: No dependencies.
FTP_ITC.1.1 The TSF shall provide a communication channel between itself and another trusted IT
product that is logically distinct from other communication channels and provides assured
19
[assignment: access control SFP(s), information flow control SFP(s)]
20
[selection: change_default, query, modify, delete, [assignment: other operations]]
21
[assignment: list of security attributes]
22
[assignment: the authorised identified roles]
23
[assignment: the authorised identified roles]
24
[assignment: list of management functions to be provided by the TSF]
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identification of its end points and protection of the channel data from modification or
disclosure.
FTP_ITC.1.2 The TSF shall permit the TSF25 to initiate communication via the trusted channel.
FTP_ITC.1.3 The TSF shall initiate communication via the trusted channel for any communication
between Zoom backend and Zoom application except for the transfer of meeting data26.
ST application note 5: The trusted channel as defined above is a TLS-connection between Zoom
application and Zoom backend. The TOE must implement TLS 1.2 and TLS 1.3 as defined in [RFC
5246, RFC 8446] and shall only use the following Cipher-Suites:
Table 12: List of used TLS Cipher Suites
Protocol Version Cipher Suite
TLS 1.2 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384
TLS_DHE_RSA_WITH_AES_256_CBC_SHA256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256
TLS_DHE_RSA_WITH_AES_128_CBC_SHA256
TLS 1.3 TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256
Additionally the client shall send the signalling cipher suite
TLS_EMPTY_RENEGOTIATION_INFO_SCSV to protect itself from renegotiation attacks
Mutual authentication is done by the following mechanisms: The client authenticates the server
through server certificates, the server authenticates the client through user authentication
(FIA_UAU.1/Client).
ST application note 6: The TOE makes use of long-lived sessions in which the Zoom backend
may initiate communication to the TOE but the session has to be started by the TOE.
ST application note 7: The trusted channel is also used to transmit SA.Meeting_Meta_Data. The
TOE shall only collect and transmit the following data:
• Topic,
• Description (Optional),
• Time,
• Date,
• Duration,
• Time Zone,
25
[selection: the TSF, another trusted IT product]
26
[assignment: list of functions for which a trusted channel is required]
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• Participant IP Addresses,
• Device/Hardware Information,
• Meeting Statistics/Metrics.
• Start Time,
• Join Time,
• Leave Time
Cryptographic operations – Zoom Meetings
FCS_CKM_EXT.1 Cryptographic key import
Hierarchical to: No other components
Dependencies: FCS_CKM.4 Cryptographic key destruction
FCS_COP.1 Cryptographic operation
[FTP_ITC.1 Inter-TSF trusted channel or
FTP_TRP.1 Trusted path]
FCS_CKM_EXT.1.1 The TSF shall import cryptographic keys from another trusted IT-entity which can
be used for AES-256 encryption27.
FCS_COP.1/AES-GCM Cryptographic operation
Hierarchical to: No other components.
Dependencies: [FDP_ITC.1 Import of user data without security
attributes, or
FDP_ITC.2 Import of user data with security
attributes, or
FCS_CKM.1 Cryptographic key generation]
FCS_CKM.4 Cryptographic key destruction
FCS_COP.1.1/AES-GCM The TSF shall perform symmetric encryption28 in accordance with a
specified cryptographic algorithm AES-GCM29 and cryptographic key sizes
256 bit30 that meet the following: NIST FIPS 197 [NIST FIPS 197], NIST
SP 800-38D [NIST SP 800-38D]31.
ST application note 8: This Iteration applies to enhanced encryption during a meeting.
Cryptographic operations – Zoom Chat
27
[assignment: cryptographic operation]
28
[assignment: list of cryptographic operations]
29
[assignment: cryptographic algorithm]
30
[assignment: cryptographic key sizes]
31
[assignment: list of standards]
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FCS_CKM.1/ACE Cryptographic key generation
Hierarchical to: No other components.
Dependencies: [FCS_CKM.2 Cryptographic key distribution, or
FCS_COP.1 Cryptographic operation]
FCS_CKM.4 Cryptographic key destruction
FCS_CKM.1.1/ACE The TSF shall generate cryptographic keys in accordance with a specified
cryptographic key generation algorithm ECC key generation with curve P-52132 and
specified cryptographic key sizes 521 Bit33 that meet the following: FIPS PUB 186-
4 B.4 and D.1.2.5 [NIST FIPS 186-4]34.
ST application note 9: This is the asymmetric key pair used for Advanced Chat Encryption.
FCS_CKM.1/Derivation Cryptographic key generation
Hierarchical to: No other components.
Dependencies: [FCS_CKM.2 Cryptographic key distribution, or
FCS_COP.1 Cryptographic operation]
FCS_CKM.4 Cryptographic key destruction
FCS_CKM.1.1/Derivation The TSF shall generate cryptographic keys in accordance with a specified
cryptographic key generation algorithm Elliptic Curve Diffie Hellman with
SHA-25635 and specified cryptographic key sizes 256 Bit36 that meet the
following: NIST SP 800-56A Rev. 3 [NIST SP 800-56A3], NIST FIPS 180-
4 [NIST FIPS 180-4]37.
ST application note 10: These are session keys used to transmit symmetric keys in ACE.
FCS_CKM.1/AES Cryptographic key generation
Hierarchical to: No other components.
Dependencies: [FCS_CKM.2 Cryptographic key distribution, or
FCS_COP.1 Cryptographic operation]
FCS_CKM.4 Cryptographic key destruction
32
[assignment: cryptographic key generation algorithm]
33
[assignment: cryptographic key sizes]
34
[assignment: list of standards]
35
[assignment: cryptographic key generation algorithm]
36
[assignment: cryptographic key sizes]
37
[assignment: list of standards]
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FCS_CKM.1.1/AES The TSF shall generate cryptographic keys in accordance with a specified
cryptographic key generation algorithm symmetric key generation38 and specified
cryptographic key sizes 256 Bit39 that meet the following: NIST FIPS 197 [NIST
FIPS 197]40.
ST application note 11: AES keys are used on multiple occasions. It is used to encrypt data
during Zoom Chats using Advanced Chat Encryption as well as during encryption of the local
database.
FCS_COP.1/AES-CBC Cryptographic operation
Hierarchical to: No other components.
Dependencies: [FDP_ITC.1 Import of user data without security attributes,
or
FDP_ITC.2 Import of user data with security attributes, or
FCS_CKM.1 Cryptographic key generation]
FCS_CKM.4 Cryptographic key destruction
FCS_COP.1.1/AES-CBC The TSF shall perform symmetric encryption41 in accordance with a
specified cryptographic algorithm AES-CBC42 and cryptographic key
sizes 256 Bit43 that meet the following: NIST FIPS 197 [NIST FIPS 197],
NIST SP 800-38A [NIST SP 800-38A]44.
ST application note 12: This iteration applies to encryption of local database as well as
encryption during of messages during Advanced Chat Encryption.
FCS_COP.1/HMAC Cryptographic operation
Hierarchical to: No other components.
Dependencies: [FDP_ITC.1 Import of user data without security attributes,
or
FDP_ITC.2 Import of user data with security attributes, or
FCS_CKM.1 Cryptographic key generation]
FCS_CKM.4 Cryptographic key destruction
38
[assignment: cryptographic key generation algorithm]
39
[assignment: cryptographic key sizes]
40
[assignment: list of standards]
41
[assignment: list of cryptographic operations]
42
[assignment: cryptographic algorithm]
43
[assignment: cryptographic key sizes]
44
[assignment: list of standards]
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FCS_COP.1.1/HMAC The TSF shall perform HMAC generation and verification45 in accordance with a
specified cryptographic algorithm HMAC-SHA51246 and cryptographic key sizes
256 Bit47 that meet the following: RFC 2104 [RFC2104], NIST FIPS 180-4 [NIST
FIPS 180-4]48.
ST application note 13: HMAC shall be used for integrity protection of the encrypted local database
(FCS_COP.1/AES-CBC).
SARS
This ST requires the TOE to be evaluated according to EAL2.
SECURITY REQUIREMENTS RATIONALE
Dependency Rationale
Table 13: Dependency Rationale
SFR Dependencies Satisfied by Explanation
FIA_UID.1 No dependencies - -
FIA_UAU.1/Client FIA_UID.1 FIA_UID.1 -
FIA_UAU.2/Meeting FIA_UID.1 FIA_UID.1 -
FIA_UAU.5 No dependencies - -
FCS_CKM_EXT.1 FCS_CKM.4
FCS_COP.1
[FTP_ITC.1, or FTP_TRP.1]
FCS_COP.1/AES-GCM
FTP_ITC.1
FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FCS_CKM.1/ACE [FCS_CKM.2, or
FCS_COP.1]
FCS_CKM.4
- The dependency to
FCS_CKM.2 or
FCS_COP.1 is not fulfilled
because the key is only
used to derive a
symmetric key according
to FCS_CKM.1/Derivation.
FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FCS_CKM.1/Derivation [FCS_CKM.2, or
FCS_COP.1]
FCS_CKM.4
FCS_COP.1/AES-CBC FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
45
[assignment: list of cryptographic operations]
46
[assignment: cryptographic algorithm]
47
[assignment: cryptographic key sizes]
48
[assignment: list of standards]
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SFR Dependencies Satisfied by Explanation
FCS_CKM.1/AES [FCS_CKM.2, or
FCS_COP.1]
FCS_CKM.4
FCS_COP.1/AES-CBC FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FCS_COP.1/AES-GCM [FDP_ITC.1, or FDP_ITC.2,
or FCS_CKM.1]
FCS_CKM.4
FCS_CKM_EXT.1 FCS_CKM_EXT.1 was
chosen instead of
FDP_ITC.1, FDP_ITC.2
and FCS_CKM.1 because
the key is imported from a
trusted IT product in the
TOEs environment under
control of the TOEs
developer.
FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FCS_COP.1/AES-CBC [FDP_ITC.1, or FDP_ITC.2,
or FCS_CKM.1]
FCS_CKM.4
FCS_CKM.1/AES
FCS_CKM.1/Derivation
FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FCS_COP.1/HMAC [FDP_ITC.1, or FDP_ITC.2,
or FCS_CKM.1]
FCS_CKM.4
FCS_CKM.1/AES FCS_CKM.4 is not fulfilled
because key deletion is
left to the OS and is not
part of TOE functionality.
FTP_ITC.1 No dependencies - -
FDP_ACC.1/UC FDP_ACF.1 FDP_ACF.1/UC -
FDP_ACF.1/UC FDP_ACC.1
FMT_MSA.3
FDP_ACC.1/UC
FMT_MSA.3/UC
-
FMT_MSA.3/UC FMT_MSA.1
FMT_SMR.1
FMT_MSA.1
FMT_SMR.1
-
FMT_MSA.1 [FDP_ACC.1, or FDP_IFC.1]
FMT_SMR.1
FMT_SMF.1
FDP_ACC.1/UC
FMT_SMR.1
FMT_SMF.1
-
FMT_SMR.1 FIA_UID.1 FIA_UID.1 FIA_UID.1 is hierarchical
to FIA_UID.1
FMT_SMF.1 No dependencies - -
Security functional requirements rationale
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Table 14: Security functional requirements rationale
O.Secure_Channel
O.Meeting_Encryption
O.Secure_Storage
O.Meeting_Authentication
O.Authentication
O.User_Control
O.User_Control_Remote
O.Advanced_Chat_Encryption
FIA_UID.1 x
FIA_UAU.1/Client x
FIA_UAU.2/Meeting x
FIA_UAU.5 x
FCS_CKM_EXT.1 x
FCS_CKM.1/ACE x
FCS_CKM.1/Derivation x
FCS_CKM.1/AES x x x
FCS_COP.1/AES-GCM x
FCS_COP.1/AES-CBC x x
FCS_COP.1/HMAC x
FTP_ITC.1 x x x
FDP_ACC.1/UC x
FDP_ACF.1/UC x
FMT_MSA.3/UC x
FMT_MSA.1 x
FMT_SMR.1 x
FMT_SMF.1 x
O.Secure_Channel
The secure channel required by this security objective is provided by FTP_ITC.1.
O.Meeting_Encryption
The encryption of meeting data is done by FCS_COP.1/AES-GCM. The meeting key is imported as defined
in FCS_CKM_EXT.1 over the trusted channel defined in FTP_ITC.1. That trusted channel also provides an
additional layer of protection for the encrypted data.
O.Secure_Storage
Zoom Chat data gets stored in an encrypted database on the host device of the TOE. The encryption is
done as defined in FCS_COP.1/AES-CBC with the key generated as in FCS_CKM.1/AES. After encryption
there is also an integrity protection mechanism in form of FCS_COP.1/HMAC applied.
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O.Meeting_Authentication
This objective requires the TOE to only let authenticated user join a meeting. This authentication is described
in FIA_UAU.2/Meeting.
O.Authentication
O.Authentication requires the TOE to authenticate its users before accessing user data. Identification and
authentication are done via FIA_UID.1 and FIA_UAU.1/Client. FIA_UAU.5 further describers the multiple
authentication methods available to users.
O.User_Control
O.User_Control requires the TOE to enforce use controls set by a TOE user while taking part in a meeting.
FMT_SMF.1 describes those controls and requires the TOE to implement them correctly.
O.User_Control_Remote
O.User_Control_Remote requires the TOE to enforce the access control rules to user controls according
the meeting security attributes. FDP_ACC.1/UC, FDP_ACF.1/UC, FMT_MSA.3/UC and FMT_MSA.1
specify the access control rules needed. FMT_SMR.1 defines the roles used for access control.
O.Advanced_Chat_Encryption
O.Advanced_Chat_Encryption requires the TOE to implement end-to-end encryption. FCS_CKM.1/ACE
creates an asymmetric key pair for the TOE user. FCS_CKM.1/Derivation derives symmetric encryption
keys for chats which is used to securely transfer a session key generated by FCS_CKM.1/AES. Encryption
is done as described in FCS_COP.1/AES-CBC. FTP_ITC.1 provides an additional layer of protection for the
encrypted data.
Security assurance requirements rationale
The EAL2 was chosen because it provides assurance by a full security target and an analysis of the SFRs
in that ST, using a functional and interface specification, guidance documentation and a basic description
of the architecture of the TOE, to understand the security behaviour. The analysis is supported by
independent testing of the TSF, evidence of developer testing based on the functional specification,
selective independent confirmation of the developer test results, and a vulnerability analysis (based upon
the functional specification, TOE design, security architecture description and guidance evidence provided)
demonstrating resistance to penetration attackers with a basic attack potential. EAL2 also provides
assurance through use of a configuration management system and evidence of secure delivery procedures.
Together, this provides assurance commensurate with the threat environment that is experienced by typical
consumers of the TOE.
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TOE SUMMARY SPECIFICATION
USER IDENTIFICATION AND AUTHENTICATION
The TOE identifies and authenticates all user before granting them access to any TSF functionality
(FIA_UID.1, FIA_UAU.1/Client). Authentication is done via password-based authentication, optionally
strengthened by two-factor-authentication using time-based-one-time-passwords (FIA_UAU.5).
MEETING AUTHENTICATION
Authentication to a meeting is password based. The user needs to be authenticated by Meeting-ID and
password to be able to access any meeting functionality (FIA_UAU.2/Meeting).
USER AND SECURITY CONTROLS
During a meeting, users are able to access controls like muting and unmuting their microphone or starting
and stopping screen sharing (FMT_SMF.1). The permissions that define what functionality is allowed to be
used by each participant are stored server-side as meeting security attributes. Those can be set by the
meeting’s host. To enforce these permissions the TOE implements a role-based access model
(FMT_SMR.1). Participants can only access functionality according to the permissions set in the meeting
security attributes. The host always has full control over his settings (FDP_ACC.1/UC, FDP_ACF.1/UC).
The default permissions are defined to allow every participant full access to their controls (FMT_MSA.3/UC).
These default permissions can be changed by the Host on a meeting by meeting basis (FMT_MSA.1).
SECURE DATA TRANSFER
All data transferred between the TOE and Zoom backend is protected by either a TLS channel (FTP_ITC.1)
or Zoom’s meeting encryption. Key generation is supported by the RNG (OE.RNG). During Zoom’s meeting
encryption the TOE performs AES-GCM encryption of all meeting data (e.g. voice, video)
(FCS_COP.1/AES-GCM). To perform meeting encryption, the TOE imports a key generated in the Zoom
backend (FCS_CKM_EXT.1). That key is generated individually for each meeting and distributed to all
participants.
ZOOM CHAT
Zoom Chat generally uses the same TLS channel as the rest of the TOE functionality (FTP_ITC.1).
Additionally, the TOE stores Zoom Chat data in a database that is encrypted using AES-CBC and integrity
protected using HMAC-SHA512 (FCS_CKM.1/AES, FCS_COP.1/AES-CBC, FCS_COP.1/HMAC).
Additionally, users can choose to make use of advanced chat encryption. For that case the TOE checks
after authentication is done, if an asymmetric elliptic curve key pair already exists. If the key pair does not
exist or is expired, the TOE generates a new user specific, long-term asymmetric elliptic curve key pair
(FCS_CKM.1/ACE). When initiating a Zoom Chat with another user, the TOE queries the Zoom Backend
for the recipient’s public key, which it then uses for an elliptic curve Diffie-Hellman key exchange to derive
a shared secret (FCS_CKM.1/Derivation). This shared secret is used to encrypt an ephemeral AES session
key (FCS_CKM.1/AES) which can be used to secure the following communication (FCS_COP.1/AES-CBC).
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USE OF CRYPTOGRAPHIC FUNCTIONS
Table 15: Cryptographic functions overview
N
o
Purpose Cryptographic
Mechanism
Standard of
Implementation
Key Size in
Bits
Security Level
above 100 Bits
1 Meeting
encryption
AES in GCM mode FIPS 197, NIST SP
800-38D
|k| = 256 yes
2 Key
Agreement
ECDH with SHA-256 NIST SP 800-56A
Rev. 3, FIPS 180-4
Key sizes
correspondi
ng to the
used elliptic
curve P-521
yes
3 Zoom Chat
encryption
AES in CBC mode FIPS 197, NIST SP
800-38A
|k| = 256 yes
4 Database
encryption
AES in CBC mode FIPS 197, NIST SP
800-38A
|k| = 256 yes
5 Database
integrity
protection
HMAC-SHA512 RFC 2104, NIST
FIPS 180-4
|k| = 256 yes
6 TLS 1.2 -
AES 256
TLS v1.2 with the
following Cipher Suites:
TLS_ECDHE_RSA_
WITH_AES_256_
GCM_SHA384,
TLS_DHE_RSA_
WITH_AES_256_
GCM_SHA384,
TLS_ECDHE_RSA_
WITH_AES_256_
CBC_SHA384,
TLS_DHE_RSA_
WITH_AES_256_
CBC_SHA256
RFC 5246, RFC
5288, RFC 5289
|k| = 256 yes
7 TLS 1.2 -
AES 128
TLS v1.2 with the
following Cipher Suites:
TLS_ECDHE_RSA_
WITH_AES_128_
GCM_SHA256,
TLS_DHE_RSA_
WITH_AES_128_
GCM_SHA256
RFC 5246, RFC
5288, RFC 5289
|k| = 128 yes
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N
o
Purpose Cryptographic
Mechanism
Standard of
Implementation
Key Size in
Bits
Security Level
above 100 Bits
TLS_ECDHE_RSA_
WITH_AES_128_
CBC_SHA256
TLS_DHE_RSA_
WITH_AES_128_
CBC_SHA256
8 TLS 1.2 -
ChaCha20
TLS v1.2 with the
following Cipher Suites:
TLS_ECDHE_RSA_
WITH_CHACHA20_
POLY1305_SHA256
TLS_DHE_RSA_
WITH_CHACHA20_
POLY1305_SHA256
RFC 5246, RFC
7905
|k| = 256 see ST application
note 14:
9 TLS 1.3 -
AES 256
TLS v1.3 with the
following Cipher Suite:
TLS_AES_256_
GCM_SHA384
RFC 8446 |k| = 256 yes
10 TLS 1.3 -
AES 128
TLS v1.3 with the
following Cipher Suite:
TLS_AES_128_
GCM_SHA256
RFC 8446 |k| = 128 yes
11 TLS 1.3 -
ChaCha20
TLS v1.3 with the
following Cipher Suite:
TLS_CHACHA20_
POLY1305_SHA256
RFC 8446 |k| = 256 see ST application
note 14:
12 Key
generation
ECC key generation with
curve P-521
FIPS PUB 186-4
B.4 and D.1.2.5
Key sizes
correspondi
ng to the
used elliptic
curve P-521
yes
13 Symmetric
key
generation
Random bit input from
OE.RNG.
- |k| = 256 yes
ST application note 14: No mathematical analysis of Cipher Suites using ChaCha20-Ploy1305
has been done.
ANNEX
REFERENCE DOCUMENTATION
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Table 16: Reference documentation
ID Document
AGD Zoom Application – Guidance Documentation, Version 1.5, 06.12.2021
CC1 Common Criteria, Part 1: Common Criteria for Information Technology Security
Evaluation,
Part 1: Introduction and general model, Version 3.1, Revision 5, April 2017
CC2 Common Criteria, Part 2: Common Criteria for Information Technology Security
Evaluation,
Part 2: Security functional components, Version 3.1, Revision 5, April 2017
CC3 Common Criteria, Part 3: Common Criteria for Information Technology Security
Evaluation,
Part 3: Security assurance components, Version 3.1, Revision 5, April 2017
NIST FIPS
186-4
Federal Information Processing Standards Publication 186-4, Digital Signature
Standard (DSS), July 2013
NIST FIPS
180-4
Federal Information Processing Standards Publication 186-4, Secure Hash
Standard (SHS), August 2015
NIST FIPS
197
Federal Information Processing Standards Publication 197, Advanced Encryption
Standard (AES), 2001
NIST SP
800-38A
NIST Special Publication 800-38A, Recommendation for Block Cipher Modes of
Operation – Methods and Techniques, 2001
NIST SP
800-38D
NIST Special Publication 800-38D, Recommendation for Block Cipher Modes of
Operation: Galois/Counter Mode (GCM) and GMAC, 2007
NIST SP
800-56A3
NIST Special Publication 800-56A Rev. 3, Recommendation for Pair-Wise Key-
Establishment Schemes Using Discrete Logarithm Cryptography, 2018
RFC 2104 RFC 2104 – HMAC: Keyed-Hashing for Message Authentication,
https://tools.ietf.org/html/rfc2104
RFC 5246 RFC 5246 – The Transport Layer Security (TLS) Protocol Version 1.2,
https://tools.ietf.org/html/rfc5246
RFC 5288 RFC 5288 - AES Galois Counter Mode (GCM) Cipher Suites for TLS,
https://datatracker.ietf.org/doc/html/rfc5288
RFC 5289 RFC 5289 - TLS Elliptic Curve Cipher Suites with SHA-256/384 and AES Galois
Counter Mode (GCM), https://datatracker.ietf.org/doc/html/rfc5289
RFC 7905 RFC 7905 - ChaCha20-Poly1305 Cipher Suites for Transport Layer Security
(TLS), https://datatracker.ietf.org/doc/html/rfc7905
RFC 8446 RFC 8446 - The Transport Layer Security (TLS) Protocol Version 1.3,
https://datatracker.ietf.org/doc/html/rfc8446
TOE-
Windows
ZoomInstaller.exe, Version 5.6.6, SHA256:
547BB69B964DB47D84D67F006A44927CD70D2B5380C83B8D3299F0CC2B96
20B5
TOE-Mac Zoom.pkg, Version 5.6.6, SHA256:
562D4FC25FF0B3AE3DF597644CD6E2CDC0513751F610E334FF23E6464C73B
F45
TOE-
Android
zoom.apk, Version 5.6.6, SHA256:
CD2B482CCE711EE0ED012B76F733398AC23988E457B9748494B90668E38AF
02F
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TOE-ios Zoom 5.6.6.ipa, Version 5.6.6, SHA256:
64A04310D2A9E00E4C2EFC8C9E1561C681BC3B74EAD778BA0F7B59B5188A
D601
TERMINOLOGY
Table 17: Terminology
Acronym Term
ACE Advanced Chat Encryption
CA Certificate Authority
E2E End-to-end
E2EE End-to-end encryption
IM Instant Messaging
PKI Public Key Infrastructure
RNG Random Number Generation
TOE Target of Evaluation
LIST OF FIGURES
Figure 1: Default participant view .................................................................................................... 6
Figure 2: Host view during a meeting ............................................................................................. 7
Figure 3: Default view for Zoom Chat.............................................................................................. 8
Figure 4: Overview of main components........................................................................................ 8
LIST OF TABLES
Table 1: TOE-Versions of the different clients ................................................................................. 5
Table 2: Supported Environments ................................................................................................. 9
Table 3: Supported Android mobile devices............................................................................... 10
Table 4: Delivery overview for the different platforms................................................................ 10
Table 5: Assets .............................................................................................................................. 14
Table 6: Threats............................................................................................................................. 15
Table 7: Organizational Security Policies ...................................................................................... 15
Table 8: Assumptions..................................................................................................................... 15
Table 9: Security Objectives for the TOE....................................................................................... 17
Table 10: Security Objectives for the TOE-environment ................................................................. 17
Table 11: Security Objectives Rationale .......................................................................................... 19
Table 12: List of used TLS Cipher Suites ....................................................................................... 27
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Table 13: Dependency Rationale..................................................................................................... 31
Table 14: Security functional requirements rationale....................................................................... 33
Table 15: Cryptographic functions overview................................................................................. 36
Table 16: Reference documentation................................................................................................ 38
Table 17: Terminology ..................................................................................................................... 39