AC.L2-3.1.11

Configure the system to terminate user sessions based on the organization’s policy. Session termination policies can be simple or sophisticated. Examples are inactivity (end the session after a specified duration (e.g., one hour ) of inactivity), day/time (all sessions are terminated at the end of the established workday), misbehavior (end the session due to an attempted policy violation), and maintenance (terminate sessions to prevent issues with an upgrade or service outage). If there is no automatic control of user sessions, an attacker can take advantage of an unattended session.

Example 1

You manage systems containing CUI for your organization and configure the system to terminate all user sessions after 1 hour of inactivity [a]. As the session timeout approaches, the system prompts users with a warning banner asking if they want to continue the session. When the session timeout does occur, the login page pops up, and the users must log in to start a new session [b].

Example 2

A user is logged into a corporate database containing CUI but is not authorized to view CUI. The user has submitted a series of queries that unintentionally violate policy, as they attempt to extract CUI that the user is not authorized to view [a]. The session terminates with a warning as a result of a violation of corporate policy [b]. The user must reestablish the session before being able to submit additional legitimate queries.

Potential Assessment Considerations

• Are the conditions in which a user session must be terminated described (e.g., after a period of inactivity or after a defined time limit) [a]?
• Are procedures documented that describe how to configure the system to enable automatic termination of user sessions after any of the defined conditions occur [b]?
• Are user sessions terminated based on organization-defined conditions [a,b]?