Level 5 CMMC - CMMC Practices

AC.3.019  

Reference: CMMC 1.02

Family: AC

Level Introduced: 3

Practice:
Terminate (automatically) user sessions after a defined condition.

CMMC Clarification:
This practice may require security policy development if it does not exist. Configure the system to end user sessions based on the organization's policy. Policy guidance for session termination usually includes circumstances, events, or specific triggers that require automatically terminating the session or logging off the user. If there is no automatic control of user sessions, an attacker can take advantage of an unattended session.

Example 1
You are the system administrator for your organization and were given the task to implement the termination of all user sessions after 1 hour of inactivity. 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 login to start a new session.

Example 2
You are logged into a corporate database containing CUI, but you are not authorized to view CUI. You have submitted a series of complex queries that violate policy, as they appear to be an attempt to extract CUI you are not authorized to view. Your session is terminated as a result of what appears to be a large query set attack, a violation of corporate policy. You must reestablish the session before you can submit additional legitimate queries.

3.1.11

Terminate (automatically) a user session after a defined condition.

Discussion:
This requirement addresses the termination of user-initiated logical sessions in contrast to the termination of network connections that are associated with communications sessions (i.e., disconnecting from the network). 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 system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions. Session termination terminates all processes associated with a user’s 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 organization-defined periods of user inactivity, targeted responses to certain types of incidents, and time-of-day restrictions on system use.

Source: NIST Special Publication 800-171 Rev. 2

AC-12

SESSION TERMINATION

Description:
The information system automatically terminates a user session after [Assignment: organization-defined conditions or trigger events requiring session disconnect].

Supplemental Guidance:
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 user’s 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. Related controls: SC-10, SC-23.

Source: NIST Special Publication 800-53 Rev. 4

Source: CMMC v1.02