AC-12: SESSION TERMINATION
TAILORED FOR INDUSTRIAL CONTROL SYSTEMS
ICS Control Baselines:
The information system automatically terminates a user session after [Assignment: organization-defined conditions or trigger events requiring session disconnect].
This control addresses the termination of user-initiated logical sessions in contrast to SC-10 which addresses the termination of network connections that are associated with communications sessions (i.e., network disconnect). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational information system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions. Session termination terminates all processes associated with a userï¿½s logical session except those processes that are specifically created by the user (i.e., session owner) to continue after the session is terminated. Conditions or trigger events requiring automatic session termination can include, for example, organization-defined periods of user inactivity, targeted responses to certain types of incidents, time-of-day restrictions on information system use.
ICS SUPPLEMENTAL GUIDANCE
Example compensating controls include providing increased auditing measures or limiting remote access privileges to key personnel.
RELATED CONTROLS: AC-12
AC-12 (1) SESSION TERMINATION | USER-INITIATED LOGOUTS / MESSAGE DISPLAYS
NOT SELECTED FOR THE NIST ISC CONTROL SET
The information system:
- (a) Provides a logout capability for user-initiated communications sessions whenever authentication is used to gain access to [Assignment: organization-defined information resources]; and
- (b) Displays an explicit logout message to users indicating the reliable termination of authenticated communications sessions.
Information resources to which users gain access via authentication include, for example, local workstations, databases, and password-protected websites/web-based services. Logout messages for web page access, for example, can be displayed after authenticated sessions have been terminated. However, for some types of interactive sessions including, for example, file transfer protocol (FTP) sessions, information systems typically send logout messages as final messages prior to terminating sessions.
- NIST Special Publication 800-82 | GUIDE TO INDUSTRIAL CONTROL SYSTEMS (ICS) SECURITY