Doc:NIST SP 800-53Ar1 Appendix F/Enhanced/AC/High

AC-1 ACCESS CONTROL POLICY AND PROCEDURES

Control: The organization develops, disseminates, and reviews/updates [Assignment: organization-defined frequency]:

a. A formal, documented access control policy that addresses purpose, scope, roles, responsibilities, management commitment, coordination among organizational entities, and compliance; and

b. Formal, documented procedures to facilitate the implementation of the access control policy and associated access controls.

Supplemental Guidance: This control is intended to produce the policy and procedures that are required for the effective implementation of selected security controls and control enhancements in the access control family. The policy and procedures are consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. Existing organizational policies and procedures may make the need for additional specific policies and procedures unnecessary. The access control policy can be included as part of the general information security policy for the organization. Access control procedures can be developed for the security program in general and for a particular information system, when required. The organizational risk management strategy is a key factor in the development of the access control policy. Related control: PM-9.

Control Enhancements: None.

Determine if: (i) the organization develops and formally documents access control policy; (ii) the organization access control policy addresses: purpose; scope; roles and responsibilities; management commitment; coordination among organizational entities; and compliance; (iii) the organization disseminates formal documented access control policy to elements within the organization having associated access control roles and responsibilities; (iv) the organization develops and formally documents access control procedures; (v) the organization access control procedures facilitate implementation of the access control policy and associated access controls; and (vi) the organization disseminates formal documented access control procedures to elements within the organization having associated access control roles and responsibilities.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy and procedures; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with access control responsibilities].

Determine if: (i) the organization defines the frequency of access control policy reviews/updates; (ii) the organization reviews/updates access control policy in accordance with organization-defined frequency; (iii) the organization defines the frequency of access control procedure reviews/updates; and (iv) the organization reviews/updates access control procedures in accordance with organization-defined frequency.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy and procedures; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with access control responsibilities].

AC-2 ACCOUNT MANAGEMENT

Control: The organization manages information system accounts, including:

a. Identifying account types (i.e., individual, group, system, application, guest/anonymous, and temporary);

b. Establishing conditions for group membership;

c. Identifying authorized users of the information system and specifying access privileges;

d. Requiring appropriate approvals for requests to establish accounts;

e. Establishing, activating, modifying, disabling, and removing accounts;

f. Specifically authorizing and monitoring the use of guest/anonymous and temporary accounts;

g. Notifying account managers when temporary accounts are no longer required and when information system users are terminated, transferred, or information system usage or need-to-know/need-to-share changes;

h. Deactivating: (i) temporary accounts that are no longer required; and (ii) accounts of terminated or transferred users;

i. Granting access to the system based on: (i) a valid access authorization; (ii) intended system usage; and (iii) other attributes as required by the organization or associated missions/business functions; and

j. Reviewing accounts [Assignment: organization-defined frequency].

Supplemental Guidance: The identification of authorized users of the information system and the specification of access privileges is consistent with the requirements in other security controls in the security plan. Users requiring administrative privileges on information system accounts receive additional scrutiny by organizational officials responsible for approving such accounts and privileged access. Related controls: AC-3, AC-4, AC-5, AC-6, AC-10, AC-17, AC-19, AC-20, AU-9, IA-4, IA-5, CM-5, CM-6, MA-3, MA-4, MA-5, SA-7, SC-13, SI-9.

Control Enhancements:

Determine if: (i) the organization manages information system accounts, including; identifying account types (i.e., individual, group, system, application, guest/anonymous, and temporary); establishing conditions for group membership; identifying authorized users of the information system and specifying access privileges; requiring appropriate approvals for requests to establish accounts; establishing, activating, modifying, disabling, and removing accounts; specifically authorizing and monitoring the use of guest/anonymous and temporary accounts; notifying account managers when temporary accounts are no longer required and when information system users are terminated, transferred, or information system usage or need-to-know/need-to-share changes; deactivating: i) temporary accounts that are no longer required; and ii) accounts of terminated or transferred users; and granting access to the system based on: a valid access authorization; intended system usage; and other attributes as required by the organization or associated missions/business functions; and (ii) the organization defines the frequency of information system account reviews; and (iii) the organization reviews information system accounts in accordance with organization-defined frequency.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing account management; security plan; list of active system accounts along with the name of the individual associated with each account; list of guest/anonymous and temporary accounts along with the name of the individual associated with each account and the date the account expires; lists of recently transferred, separated, or terminated employees; list of recently disabled information system accounts along with the name of the individual associated with each account; system-generated records with user IDs and last login date; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with account management responsibilities].

(1) The organization employs automated mechanisms to support the management of information system accounts.

Determine if the organization employs automated mechanisms to support information system account management functions.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Procedures addressing account management; information system design documentation; information system configuration settings and associated documentation; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing account management functions].

(2) The information system automatically terminates temporary and emergency accounts after [Assignment: organization-defined time period for each type of account].

Determine if: (i) the organization defines a time period for each type of account after which the information system terminates temporary and emergency accounts; and (ii) the information system automatically terminates temporary and emergency accounts after organization-defined time period for each type of account.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Security plan; information system design documentation; information system configuration settings and associated documentation; information system-generated list of active accounts; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing account management functions].

(3) The information system automatically disables inactive accounts after [Assignment: organization-defined time period].

Determine if: (i) the organization defines in a time period after which the information system disables inactive accounts; and (ii) the information system automatically disables inactive accounts after organization-defined time period.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Procedures addressing account management; security plan; information system design documentation; information system configuration settings and associated documentation; information system-generated list of last login dates; information system-generated list of active accounts; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing account management functions].

(4) The information system automatically audits account creation, modification, disabling, and termination actions and notifies, as required, appropriate individuals.

Determine if: (i) the information system automatically audits: account creation; modification; disabling; and termination actions; and (ii) the information system notifies, as required, appropriate individuals.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Procedures addressing account management; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing account management functions].

AC-3 ACCESS ENFORCEMENT

Control: The information system enforces approved authorizations for logical access to the system in accordance with applicable policy.

Supplemental Guidance: Access control policies (e.g., identity-based policies, role-based policies, attribute-based policies) and access enforcement mechanisms (e.g., access control lists, access control matrices, cryptography) are employed by organizations to control access between users (or processes acting on behalf of users) and objects (e.g., devices, files, records, processes, programs, domains) in the information system. In addition to enforcing authorized access at the information-system level, access enforcement mechanisms are employed at the application level, when necessary, to provide increased information security for the organization. Consideration is given to the implementation of an audited, explicit override of automated mechanisms in the event of emergencies or other serious events. If encryption of stored information is employed as an access enforcement mechanism, the cryptography used is FIPS 140-2 (as amended) compliant. For classified information, the cryptography used is largely dependent on the classification level of the information and the clearances of the individuals having access to the information. Mechanisms implemented by AC-3 are configured to enforce authorizations determined by other security controls. Related controls: AC-2, AC-4, AC-5, AC-6, AC-16, AC-17, AC-18, AC-19, AC-20, AC-21, AC-22, AU-9, CM-5, CM-6, MA-3, MA-4, MA-5, SA-7, SC-13, SI-9.

Control Enhancements:

Determine if the information system enforces approved authorizations for logical access to the system in accordance with applicable policy.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing access enforcement; information system configuration settings and associated documentation; list of approved authorizations (user privileges); information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing access enforcement policy].

AC-4 INFORMATION FLOW ENFORCEMENT

Control: The information system enforces approved authorizations for controlling the flow of information within the system and between interconnected systems in accordance with applicable policy.

Supplemental Guidance: Information flow control regulates where information is allowed to travel within an information system and between information systems (as opposed to who is allowed to access the information) and without explicit regard to subsequent accesses to that information. A few examples of flow control restrictions include: keeping export controlled information from being transmitted in the clear to the Internet, blocking outside traffic that claims to be from within the organization, and not passing any web requests to the Internet that are not from the internal web proxy. Information flow control policies and enforcement mechanisms are commonly employed by organizations to control the flow of information between designated sources and destinations (e.g., networks, individuals, devices) within information systems and between interconnected systems. Flow control is based on the characteristics of the information and/or the information path. Specific examples of flow control enforcement can be found in boundary protection devices (e.g., proxies, gateways, guards, encrypted tunnels, firewalls, and routers) that employ rule sets or establish configuration settings that restrict information system services, provide a packet-filtering capability based on header information, or message-filtering capability based on content (e.g., using key word searches or document characteristics). Mechanisms implemented by AC-4 are configured to enforce authorizations determined by other security controls. Related controls: AC-17, AC-19, AC-21, CM-7, SA-8, SC-2, SC-5, SC-7, SC-18.

Control Enhancements:

Determine if: (i) the organization defines applicable policy for controlling the flow of information within the system and between interconnected systems; (ii) the organization defines approved authorizations for controlling the flow of information within the system and between interconnected systems in accordance with applicable policy; and (iii) the information system enforces approved authorizations for controlling the flow of information within the system and between interconnected systems in accordance with applicable policy.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing information flow enforcement; information system design documentation; information system configuration settings and associated documentation; information system baseline configuration; list of information flow authorizations; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing information flow enforcement policy].

AC-5 SEPARATION OF DUTIES

Control: The organization:

a. Separates duties of individuals as necessary, to prevent malevolent activity without collusion;

b. Documents separation of duties; and

c. Implements separation of duties through assigned information system access authorizations.

Supplemental Guidance: Examples of separation of duties include: (i) mission functions and distinct information system support functions are divided among different individuals/roles; (ii) different individuals perform information system support functions (e.g., system management, systems programming, configuration management, quality assurance and testing, network security); (iii) security personnel who administer access control functions do not administer audit functions; and (iv) different administrator accounts for different roles. Access authorizations defined in this control are implemented by control AC-3. Related controls: AC-3.

Control Enhancements: None.

Determine if: (i) the organization separates duties of individuals as necessary, to prevent malevolent activity without collusion; (ii) the organization documents separation of duties; and (iii) the organization implements separation of duties through assigned information system access authorizations.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing divisions of responsibility and separation of duties; information system configuration settings and associated documentation; list of divisions of responsibility and separation of duties; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for defining appropriate divisions of responsibility and separation of duties].

Test: [SELECT FROM: Automated mechanisms implementing separation of duties policy].

AC-6 LEAST PRIVILEGE

Control: The organization employs the concept of least privilege, allowing only authorized accesses for users (and processes acting on behalf of users) which are necessary to accomplish assigned tasks in accordance with organizational missions and business functions.

Supplemental Guidance: The access authorizations defined in this control are largely implemented by control AC-3. The organization employs the concept of least privilege for specific duties and information systems (including specific ports, protocols, and services) in accordance with risk assessments as necessary to adequately mitigate risk to organizational operations and assets, individuals, other organizations, and the Nation. Related controls: AC-2, AC-3, CM-7.

Control Enhancements:

Determine if the organization employs the concept of least privilege, allowing only authorized accesses for users (and processes acting on behalf of users) which are necessary to accomplish assigned tasks in accordance with organizational missions and business functions.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing least privilege; list of assigned access authorizations (user privileges); information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for defining least privileges necessary to accomplish specified tasks].

(1) The organization explicitly authorizes access to [Assignment: organization-defined list of security functions (deployed in hardware, software, and firmware) and security-relevant information].

Enhancement Supplemental Guidance: Establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters are examples of security functions. Explicitly authorized personnel include, for example, security administrators, system and network administrators, system security officers, system maintenance personnel, system programmers, and other privileged users. Related control: AC-17.

Determine if: (i) the organization defines the security functions (deployed in hardware, software, and firmware) and security-relevant information for which access must be explicitly authorized; and (ii) the organization explicitly authorizes access to the organization-defined security functions and security-relevant information.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing least privilege; list of security functions and security-relevant information for which access must be explicitly authorized; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for defining least privileges necessary to accomplish specified tasks].

(2) The organization requires that users of information system accounts, or roles, with access to [Assignment: organization-defined list of security functions or security-relevant information], use non-privileged accounts, or roles, when accessing other system functions, and if feasible, audits any use of privileged accounts, or roles, for such functions.

Enhancement Supplemental Guidance: This control enhancement is intended to limit exposure due to operating from within a privileged account or role. The inclusion of role is intended to address those situations where an access control policy such as Role Based Access Control (RBAC) is being implemented and where a change of role provides the same degree of assurance in the change of access authorizations for both the user and all processes acting on behalf of the user as would be provided by a change between a privileged and non-privileged account. Audit of privileged activity may require physical separation employing information systems on which the user does not have privileged access.

Determine if: (i) the organization defines the security functions or security-relevant information to which users of information system accounts, or roles, have access; and (ii) the organization requires that users of information system accounts, or roles, with access to organization-defined security functions or security-relevant information, use non-privileged accounts, or roles, when accessing other system functions; and (iii) the organization, if deemed feasible, audits any use of privileged accounts, or roles, with access to organization-defined security functions or security-relevant information, when accessing other system functions.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing least privilege; list of system-generated security functions or security-relevant information assigned to information system accounts or roles; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for defining least privileges necessary to accomplish specified tasks].

AC-7 UNSUCCESSFUL LOGIN ATTEMPTS

Control: The information system:

a. Enforces a limit of [Assignment: organization-defined number] consecutive invalid login attempts by a user during a [Assignment: organization-defined time period]; and

b. Automatically [Selection: locks the account/node for an [Assignment: organization-defined time period]; locks the account/node until released by an administrator; delays next login prompt according to [Assignment: organization-defined delay algorithm when the maximum number of unsuccessful attempts is exceeded. The control applies regardless of whether the login occurs via a local or network connection.

Supplemental Guidance: Due to the potential for denial of service, automatic lockouts initiated by the information system are usually temporary and automatically release after a predetermined time period established by the organization. If a delay algorithm is selected, the organization may chose to employ different algorithms for different information system components based on the capabilities of those components. Response to unsuccessful login attempts may be implemented at both the operating system and the application levels. This control applies to all accesses other than those accesses explicitly identified and documented by the organization in AC-14.

Control Enhancements:

Determine if: (i) the organization defines the maximum number of consecutive invalid login attempts to the information system by a user and the time period in which the consecutive invalid attempts occur; (ii) the information system enforces the organization-defined limit of consecutive invalid login attempts by a user during the organization-defined time period; (iii) the organization defines action to be taken by the system when the maximum number of unsuccessful login attempts is exceeded as: lock out the account/node for a specified time period; lock out the account/note until released by an administrator; or delay the next login prompt according to organization-defined delay algorithm; (iv) the information system either automatically locks the account/node for the organization-defined time period, locks the account/node until released by an administrator, or delays next login prompt for the organization-defined delay period when the maximum number of unsuccessful login attempts is exceeded; and (v) the information system performs the organization-defined actions when the maximum number of unsuccessful login attempts is exceeded regardless of whether the login occurs via a local or network connection.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing unsuccessful login attempts; security plan; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for unsuccessful login attempts].

AC-8 SYSTEM USE NOTIFICATION

Control: The information system:

a. Displays an approved system use notification message or banner before granting access to the system that provides privacy and security notices consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance and states that: (i) users are accessing a U.S. Government information system; (ii) system usage may be monitored, recorded, and subject to audit; (iii) unauthorized use of the system is prohibited and subject to criminal and civil penalties; and (iv) use of the system indicates consent to monitoring and recording;

b. Retains the notification message or banner on the screen until users take explicit actions to log on to or further access the information system; and

c. For publicly accessible systems: (i) displays the system use information when appropriate, before granting further access; (ii) displays references, if any, to monitoring, recording, or auditing that are consistent with privacy accommodations for such systems that generally prohibit those activities; and (iii) includes in the notice given to public users of the information system, a description of the authorized uses of the system.

Supplemental Guidance: System use notification messages can be implemented in the form of warning banners displayed when individuals log in to the information system. System use notification is intended only for information system access that includes an interactive login interface with a human user and is not intended to require notification when an interactive interface does not exist.

Control Enhancements: None.

Determine if: (i) the organization approves the information system use notification message or banner to be displayed by the information system before granting access to the system; (ii) the information system displays the approved system use notification message or banner before granting access to the system that provides privacy and security notices consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance and states that: users are accessing a U.S. Government information system; system usage may be monitored, recorded, and subject to audit; unauthorized use of the system is prohibited and subject to criminal and civil penalties; and use of the system indicates consent to monitoring and recording; and (iii) the information system retains the notification message or banner on the screen until the user takes explicit actions to log on to or further access the information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; privacy and security policies; procedures addressing system use notification; documented approval of information system use notification messages or banners; information system notification messages; information system configuration settings and associated documentation; information system audit records for user acceptance of notification message or banner; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for system use notification].

Determine if: (i) the information system (for publicly accessible systems) displays the system use information when appropriate, before granting further access; (ii) the information system (for publicly accessible systems) displays references, if any, to monitoring, recording, or auditing that are consistent with privacy accommodations for such systems that generally prohibit those activities; and (iii) the information system (for publicly accessible systems) includes in the notice given to public users of the information system, a description of the authorized uses of the information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; privacy and security policies; procedures addressing system use notification; documented approval of information system use notification messages or banners; information system notification messages; information system configuration settings and associated documentation; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for system use notification].

AC-10 CONCURRENT SESSION CONTROL

Control: The information system limits the number of concurrent sessions for each system account to [Assignment: organization-defined number].

Supplemental Guidance: The organization may define the maximum number of concurrent sessions for an information system account globally, by account type, by account, or a combination. This control addresses concurrent sessions for a given information system account and does not address concurrent sessions by a single user via multiple system accounts.

Control Enhancements: None.

Determine if: (i) the organization defines the maximum number of concurrent sessions to be allowed for each system account; and (ii) the information system limits the number of concurrent sessions for each system account to the organization-defined number of sessions.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing concurrent session control; information system design documentation; information system configuration settings and associated documentation; security plan; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for concurrent session control].

AC-11 SESSION LOCK

Control: The information system:

a. Prevents further access to the system by initiating a session lock after [Assignment: organization-defined time period] of inactivity or upon receiving a request from a user; and

b. Retains the session lock until the user reestablishes access using established identification and authentication procedures.

Supplemental Guidance: A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. This is typically at the operating system-level, but may be at the application-level. A session lock is not a substitute for logging out of the information system, for example, if the organization requires users to log out at the end of the workday.

Control Enhancements:

Determine if: (i) the organization defines the time period of user inactivity after which the information system initiates a session lock; (ii) the information system initiates a session lock after the organization-defined time period of inactivity or upon receiving a request from a user; (iii) the information system retains the session lock until the user reestablishes access using established identification and authentication procedures.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing session lock; information system design documentation; information system configuration settings and associated documentation; security plan; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for session lock].

AC-14 PERMITTED ACTIONS WITHOUT IDENTIFICATION OR AUTHENTICATION

Control: The organization:

a. Identifies specific user actions that can be performed on the information system without identification or authentication; and

b. Documents and provides supporting rationale in the security plan for the information system, user actions not requiring identification and authentication.

Supplemental Guidance: This control is intended for those specific instances where an organization determines that no identification and authentication is required; it is not, however, mandating that such instances exist in given information system. The organization may allow a limited number of user actions without identification and authentication (e.g., when individuals access public websites or other publicly accessible federal information systems such as http://www.usa.gov). Organizations also identify any actions that normally require identification or authentication but may under certain circumstances (e.g., emergencies), allow identification or authentication mechanisms to be bypassed. Such bypass may be, for example, via a software-readable physical switch that commands bypass of the login functionality and is protected from accidental or unmonitored use. This control does not apply to situations where identification and authentication have already occurred and are not being repeated, but rather to situations where identification and/or authentication have not yet occurred. Related control: CP-2, IA-2.

Control Enhancements:

Determine if: (i) the organization identifies specific user actions that can be performed on the information system without identification or authentication; and (ii) the organization documents and provides supporting rationale in the security plan for the information system, user actions not requiring identification and authentication.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing permitted actions without identification and authentication; information system configuration settings and associated documentation; security plan; list of information system actions that can be performed without identification and authentication; information system audit records; other relevant documents or records].

(1) The organization permits actions to be performed without identification and authentication only to the extent necessary to accomplish mission/business objectives.

Determine if the organization permits actions to be performed without identification and authentication only to the extent necessary to accomplish mission/business objectives.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing permitted actions without identification and authentication; information system configuration settings and associated documentation; security plan; list of information system actions that can be performed without identification and authentication; information system audit records; other relevant documents or records].

AC-17 REMOTE ACCESS

Control: The organization:

a. Documents allowed methods of remote access to the information system;

b. Establishes usage restrictions and implementation guidance for each allowed remote access method;

c. Monitors for unauthorized remote access to the information system;

d. Authorizes remote access to the information system prior to connection; and

e. Enforces requirements for remote connections to the information system.

Supplemental Guidance: This control requires explicit authorization prior to allowing remote access to an information system without specifying a specific format for that authorization. For example, while the organization may deem it appropriate to use a system interconnection agreement to authorize a given remote access, such agreements are not required by this control. Remote access is any access to an organizational information system by a user (or process acting on behalf of a user) communicating through an external network (e.g., the Internet). Examples of remote access methods include dial-up, broadband, and wireless (see AC-18 for wireless access). A virtual private network when adequately provisioned with appropriate security controls, is considered an internal network (i.e., the organization establishes a network connection between organization-controlled endpoints in a manner that does not require the organization to depend on external networks to protect the confidentiality or integrity of information transmitted across the network). Remote access controls are applicable to information systems other than public web servers or systems specifically designed for public access. Enforcing access restrictions associated with remote connections is accomplished by control AC-3. Related controls: AC-3, AC-18, AC-20, IA-2, IA-3, IA-8, MA-4.

Control Enhancements:

Determine if: (i) the organization documents allowed methods of remote access to the information system; (ii) the organization establishes usage restrictions and implementation guidance for each allowed remote access method; (iii) the organization monitors for unauthorized remote access to the information system; (iv) the organization authorizes remote access to the information system prior to connection; and (v) the organization enforces requirements for remote connections to the information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with remote access authorization, monitoring, and control responsibilities].

Test: [SELECT FROM: Remote access methods for the information system].

(1) The organization employs automated mechanisms to facilitate the monitoring and control of remote access methods.

Enhancement Supplemental Guidance: Automated monitoring of remote access sessions allows organizations to audit user activities on a variety of information system components (e.g., servers, workstations, notebook/laptop computers) and to ensure compliance with remote access policy.

Determine if the organization employs automated mechanisms to facilitate the monitoring and control of remote access methods.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system configuration settings and associated documentation; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for remote access].

(2) The organization uses cryptography to protect the confidentiality and integrity of remote access sessions.

Enhancement Supplemental Guidance: The encryption strength of mechanism is selected based on the security categorization of the information. Related controls: SC-8, SC-9, SC-13.

Determine if the organization uses cryptography to protect the confidentiality and integrity of remote access sessions.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system design documentation; information system configuration settings and associated documentation; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing cryptographic protections for remote access].

(3) The information system routes all remote accesses through a limited number of managed access control points.

Enhancement Supplemental Guidance: Related control: SC-7.

Determine if: (i) the organization defines a limited number of managed access control points for remote access to the information system; and (ii) the information system routes all remote accesses through managed access control points.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system design documentation; list of managed access control points; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for remote access].

(4) The organization authorizes the execution of privileged commands and access to security-relevant information via remote access only for compelling operational needs and documents the rationale for such access in the security plan for the information system.

Enhancement Supplemental Guidance: Related control: AC-6.

Determine if: (i) the organization authorizes the execution of privileged commands and access to security-relevant information via remote access only for compelling operational needs; and (ii) the organization documents the rationale for such access in the security plan for the information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system configuration settings and associated documentation; security plan; information system audit records; other relevant documents or records].

(5) The organization monitors for unauthorized remote connections to the information system [Assignment: organization-defined frequency], and takes appropriate action if an unauthorized connection is discovered.

Determine if: (i) the organization defines the frequency of monitoring for unauthorized remote connections to the information system; (ii) the organization monitors for unauthorized remote connections to the information system in accordance with the organization-defined frequency; (iii) the organization defines the appropriate action(s) to be taken if an unauthorized connection is discovered; and (iv) the organization takes organization-defined appropriate action(s) if an unauthorized connection is discovered.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for monitoring remote connections to the information system].

(7) The organization ensures that remote sessions for accessing [Assignment: organization-defined list of security functions and security-relevant information] employ [Assignment: organization-defined additional security measures] and are audited.

Enhancement Supplemental Guidance: Additional security measures are typically above and beyond standard bulk or session layer encryption (e.g., Secure Shell [SSH], Virtual Private Networking [VPN] with blocking mode enabled). Related controls: SC-8, SC-9.

Determine if: (i) the organization defines the security functions and security-relevant information that can be accessed using remote sessions; (ii) the organization defines the additional security measures to be employed for remote sessions used to access organization-defined security functions and security-relevant information; (iii) the organization employs organization-defined additional security measures for remote sessions used to access organization-defined security functions and security-relevant information; and (iv) the organization audits remote sessions for accessing organization-defined security functions and security-relevant information.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for remote access].

(8) The organization disables [Assignment: organization-defined networking protocols within the information system deemed to be nonsecure] except for explicitly identified components in support of specific operational requirements.

Enhancement Supplemental Guidance: The organization can either make a determination of the relative security of the networking protocol or base the security decision on the assessment of other entities. Bluetooth and peer-to-peer networking are examples of less than secure networking protocols.

Determine if: (i) the organization defines the networking protocols within the information system deemed to be nonsecure; and (ii) the organization disables the organization-defined networking protocols within the information system deemed to be nonsecure except for explicitly identified components in support of specific operational requirements.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing remote access to the information system; information system design documentation; information system configuration settings and associated documentation; security plan; list of networking protocols deemed to be non-secure; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms disabling networking protocols deemed to be non-secure].

AC-18 WIRELESS ACCESS

Control: The organization:

a. Establishes usage restrictions and implementation guidance for wireless access;

b. Monitors for unauthorized wireless access to the information system;

c. Authorizes wireless access to the information system prior to connection; and

d. Enforces requirements for wireless connections to the information system.

Supplemental Guidance: Wireless technologies include, but are not limited to, microwave, satellite, packet radio (UHF/VHF), 802.11x, and Bluetooth. Wireless networks use authentication protocols (e.g., EAP/TLS, PEAP), which provide credential protection and mutual authentication. In certain situations, wireless signals may radiate beyond the confines and control of organization-controlled facilities. Related controls: AC-3, IA-2, IA-3, IA-8.

Control Enhancements:

Determine if: (i) the organization establishes usage restrictions and implementation guidance for wireless access; (ii) the organization monitors for unauthorized wireless access to the information system; (iii) the organization authorizes wireless access to the information system prior to connection; and (iv) the organization enforces requirements for wireless connections to the information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing wireless implementation and usage (including restrictions); activities related to wireless monitoring, authorization, and enforcement; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel responsible for authorizing, monitoring or controlling the use of wireless technologies in the information system].

Test: [SELECT FROM: Wireless access usage and restrictions].

(1) The information system protects wireless access to the system using authentication and encryption.

Enhancement Supplemental Guidance: Authentication applies to user, device, or both as necessary. Related control: SC-13.

Determine if the information system protects wireless access to the system using authentication and encryption.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing wireless implementation and usage (including restrictions); information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for wireless access to the information system].

(2) The organization monitors for unauthorized wireless connections to the information system, including scanning for unauthorized wireless access points [Assignment: organization-defined frequency], and takes appropriate action if an unauthorized connection is discovered.

Enhancement Supplemental Guidance: Organizations proactively search for unauthorized wireless connections including the conduct of thorough scans for unauthorized wireless access points. The scan is not necessarily limited to only those areas within the facility containing the information systems, yet is conducted outside of those areas only as needed to verify that unauthorized wireless access points are not connected to the system.

Determine if: (i) the organization defines the frequency of monitoring for unauthorized wireless connections to the information system, including scans for unauthorized wireless access points; (ii) the organization monitors for unauthorized wireless connections to the information system, including scanning for unauthorized wireless access points, in accordance with organization-defined frequency; (iii) the organization defines the appropriate action(s) to be taken if an unauthorized connection is discovered; and (iv) the organization takes appropriate action(s) if an unauthorized connection discovered.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing wireless implementation and usage (including restrictions); wireless scanning reports; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel responsible for monitoring wireless connections to the information system].

Test: [SELECT FROM: Scanning procedures for detecting unauthorized wireless connections and access points].

(4) The organization does not allow users to independently configure wireless networking capabilities.

Determine if the organization does not allow users to independently configure wireless networking capabilities.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing wireless implementation and usage (including restrictions); information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms preventing independent configuration of wireless networking capabilities].

(5) The organization confines wireless communications to organization-controlled boundaries.

Enhancement Supplemental Guidance: Actions that may be taken by the organization to confine wireless communications to organization-controlled boundaries include: (i) reducing the power of the wireless transmission such that it cannot transit the physical perimeter of the organization; (ii) employing measures such as TEMPEST to control wireless emanations; and (iii) configuring the wireless access such that it is point to point in nature.

Determine if the organization confines wireless communications to organization-controlled boundaries.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing wireless implementation and usage (including restrictions); information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing the access control policy for wireless access to the information system; Wireless connections and access points outside of organizational boundaries using scanning devices.].

AC-19 ACCESS CONTROL FOR MOBILE DEVICES

Control: The organization:

a. Establishes usage restrictions and implementation guidance for organization-controlled mobile devices;

b. Authorizes connection of mobile devices meeting organizational usage restrictions and implementation guidance to organizational information systems;

c. Monitors for unauthorized connections of mobile devices to organizational information systems;

d. Enforces requirements for the connection of mobile devices to organizational information systems;

e. Disables information system functionality that provides the capability for automatic execution of code on mobile devices without user direction;

f. Issues specially configured mobile devices to individuals traveling to locations that the organization deems to be of significant risk in accordance with organizational policies and procedures; and

g. Applies [Assignment: organization-defined inspection and preventative measures] to mobile devices returning from locations that the organization deems to be of significant risk in accordance with organizational policies and procedures.

Supplemental Guidance: Mobile devices include portable storage media (e.g., USB memory sticks, external hard disk drives) and portable computing and communications devices with information storage capability (e.g., notebook/laptop computers, personal digital assistants, cellular telephones, digital cameras, and audio recording devices). Organization-controlled mobile devices include those devices for which the organization has the authority to specify and the ability to enforce specific security requirements. Usage restrictions and implementation guidance related to mobile devices include, for example, configuration management, device identification and authentication, implementation of mandatory protective software (e.g., malicious code detection, firewall), scanning devices for malicious code, updating virus protection software, scanning for critical software updates and patches, conducting primary operating system (and possibly other resident software) integrity checks, and disabling unnecessary hardware (e.g., wireless, infrared). Examples of information system functionality that provide the capability for automatic execution of code are AutoRun and AutoPlay.

Organizational policies and procedures for mobile devices used by individuals departing on and returning from travel include, for example, determining which locations are of concern, defining required configurations for the devices, ensuring that the devices are configured as intended before travel is initiated, and applying specific measures to the device after travel is completed. Specially configured mobile devices include, for example, computers with sanitized hard drives, limited applications, and additional hardening (e.g., more stringent configuration settings). Specified measures applied to mobile devices upon return from travel include, for example, examining the device for signs of physical tampering and purging/reimaging the hard disk drive. Protecting information residing on mobile devices is covered in the media protection family. Related controls: MP-4, MP-5.

Control Enhancements:

Determine if: (i) the organization establishes usage restrictions and implementation guidance for organization-controlled portable and mobile devices; (ii) the organization authorizes connection of mobile devices meeting organizational usage restrictions and implementation guidance to organizational information systems; (iii) the organization monitors for unauthorized connections of mobile devices to organizational information systems; (iv) the organization enforces requirements for the connection of mobile devices to organizational information systems; (v) the organization disables information system functionality that provides the capability for automatic execution of code on mobile devices without user direction; (vi) the organization issues specially configured mobile devices to individuals traveling to locations that the organization deems to be of significant risk in accordance with organizational policies and procedures; (vii) the organization defines the inspection and preventative measures to be applied to mobile devices returning from locations that the organization deems to be of significant risk; and (viii) the organization applies organization-defined inspection and preventative measures to mobile devices returning from locations that the organization deems to be of significant risk in accordance with organizational policies and procedures.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing access control for portable and mobile devices; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel who use portable and mobile devices to access the information system].

Test: [SELECT FROM: Automated mechanisms implementing access control policy for portable and mobile devices].

(1) The organization restricts the use of writable, removable media in organizational information systems.

Determine if the organization restricts the use of writable, removable media in organizational information systems.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing access control for portable and mobile devices; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel who use portable and mobile devices to access the information system].

Test: [SELECT FROM: Automated mechanisms implementing access control policy for portable and mobile devices].

(2) The organization prohibits the use of personally owned, removable media in organizational information systems.

Determine if the organization prohibits the use of personally owned, removable media in organizational information systems.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing access control for portable and mobile devices; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing access control policy for portable and mobile devices].

(3) The organization prohibits the use of removable media in organizational information systems when the media has no identifiable owner.

Enhancement Supplemental Guidance: An identifiable owner (e.g., individual, organization, or project) for removable media helps to reduce the risk of using such technology by assigning responsibility and accountability for addressing known vulnerabilities in the media (e.g., malicious code insertion).

Determine if the organization prohibits the use of removable media in organizational information systems when the media has no identifiable owner.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing access control for portable and mobile devices; information system design documentation; information system configuration settings and associated documentation; information system audit records; other relevant documents or records].

Test: [SELECT FROM: Automated mechanisms implementing access control policy for portable and mobile devices].

AC-20 USE OF EXTERNAL INFORMATION SYSTEMS

Control: The organization establishes terms and conditions, consistent with any trust relationships established with other organizations owning, operating, and/or maintaining external information systems, allowing authorized individuals to:

a. Access the information system from the external information systems; and

b. Process, store, and/or transmit organization-controlled information using the external information systems.

Supplemental Guidance: External information systems are information systems or components of information systems that are outside of the authorization boundary established by the organization and for which the organization typically has no direct supervision and authority over the application of required security controls or the assessment of security control effectiveness. External information systems include, but are not limited to: (i) personally owned information systems (e.g., computers, cellular telephones, or personal digital assistants); (ii) privately owned computing and communications devices resident in commercial or public facilities (e.g., hotels, convention centers, or airports); (iii) information systems owned or controlled by nonfederal governmental organizations; and (iv) federal information systems that are not owned by, operated by, or under the direct supervision and authority of the organization. For some external systems, in particular those systems operated by other federal agencies, including organizations subordinate to those agencies, the trust relationships that have been established between those organizations and the originating organization may be such, that no explicit terms and conditions are required. In effect, the information systems of these organizations would not be considered external. These situations typically occur when, for example, there is some pre-existing sharing or trust agreement (either implicit or explicit) established between federal agencies and/or organizations subordinate to those agencies, or such trust agreements are specified by applicable laws, Executive Orders, directives, or policies. Authorized individuals include organizational personnel, contractors, or any other individuals with authorized access to the organizational information system and over which the organization has the authority to impose rules of behavior with regard to system access. The restrictions that an organization imposes on authorized individuals need not be uniform, as those restrictions are likely to vary depending upon the trust relationships between organizations. Thus, an organization might impose more stringent security restrictions on a contractor than on a state, local, or tribal government.

This control does not apply to the use of external information systems to access public interfaces to organizational information systems and information (e.g., individuals accessing federal information through http://www.usa.gov). The organization establishes terms and conditions for the use of external information systems in accordance with organizational security policies and procedures. The terms and conditions address as a minimum; (i) the types of applications that can be accessed on the organizational information system from the external information system; and (ii) the maximum security categorization of information that can be processed, stored, and transmitted on the external information system. This control defines access authorizations enforced by AC-3, rules of behavior requirements enforced by PL-4, and session establishment rules enforced by AC-17. Related controls: AC-3, AC-17, PL-4.

Control Enhancements:

Determine if: (i) the organization identifies individuals authorized to: access the information system from the external information systems; and process, store, and/or transmit organization-controlled information using the external information systems; and (ii) the organization establishes terms and conditions, consistent with any trust relationships established with other organizations owning, operating, and/or maintaining external information systems, allowing authorized individuals to: access the information system from the external information systems; and process, store, and/or transmit organization-controlled information using the external information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing the use of external information systems; external information systems terms and conditions; list of types of applications accessible from external information systems; maximum security categorization for information processed, stored, or transmitted on external information systems; information system configuration settings and associated documentation; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel with responsibilities for defining terms and conditions for use of external information systems to access organizational systems].

(1) The organization permits authorized individuals to use an external information system to access the information system or to process, store, or transmit organization-controlled information only when the organization:

(a) Can verify the implementation of required security controls on the external system as specified in the organization's information security policy and security plan; or

(b) Has approved information system connection or processing agreements with the organizational entity hosting the external information system.

Determine if the organization permits authorized individuals to use an external information system to access the information system or to process, store, or transmit organization-controlled information only when the organization: can verify the implementation of required security controls on the external system as specified in the organization's information security policy and security plan; or has approved information system connection or processing agreements with the organizational entity hosting the external information system.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing the use of external information systems; security plan; information system connection or processing agreements; account management documents; other relevant documents or records].

(2) The organization limits the use of organization-controlled portable storage media by authorized individuals on external information systems.

Enhancement Supplemental Guidance: Limits on the use of organization-controlled portable storage media in external information systems can include, for example, complete prohibition of the use of such devices or restrictions on how the devices may be used and under what conditions the devices may be used.

Determine if the organization limits the use of organization-controlled portable storage media by authorized individuals on external information systems.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing the use of external information systems; security plan; information system configuration settings and associated documentation; information system connection or processing agreements; account management documents; other relevant documents or records].

AC-22 PUBLICLY ACCESSIBLE CONTENT

Control: The organization:

a. Designates individuals authorized to post information onto an organizational information system that is publicly accessible;

b. Trains authorized individuals to ensure that publicly accessible information does not contain nonpublic information;

c. Reviews the proposed content of publicly accessible information for nonpublic information prior to posting onto the organizational information system;

d. Reviews the content on the publicly accessible organizational information system for nonpublic information [Assignment: organization-defined frequency]; and

e. Removes nonpublic information from the publicly accessible organizational information system, if discovered.

Supplemental Guidance: Nonpublic information is any information for which the general public is not authorized access in accordance with federal laws, Executive Orders, directives, policies, regulations, standards, or guidance. Information protected under the Privacy Act and vendor proprietary information are examples of nonpublic information. This control addresses posting information on an organizational information system that is accessible to the general public, typically without identification or authentication. The posting of information on non-organization information systems is covered by appropriate organizational policy. Related controls: AC-3, AU-13.

Control Enhancements: None.

Determine if: (i) the organization designates individuals authorized to post information onto an organizational information system that is publicly accessible; (ii) the organization trains authorized individuals to ensure that publicly accessible information does not contain nonpublic information; (iii) the organization reviews the proposed content of publicly accessible information for nonpublic information prior to posting onto the organizational information system; (iv) the organization defines the frequency of reviews of the content on the publicly accessible organizational information system for nonpublic information; (v) the organization reviews the content on the publicly accessible organizational information system for nonpublic information in accordance with the organization-defined frequency; and (vi) the organization removes nonpublic information from the publicly accessible organizational information system, if discovered.

POTENTIAL ASSESSMENT METHODS AND OBJECTS:

Examine: [SELECT FROM: Access control policy; procedures addressing publicly accessible content; list of users authorized to post publicly accessible content on organizational information systems; training materials and/or records; records of publicly accessible information reviews; records of response to nonpublic information on public Web sites; system audit logs; security awareness training records; other relevant documents or records].

Interview: [SELECT FROM: Organizational personnel responsible for managing publicly accessible information posted on organizational information systems].