AC.L2-3.1.10

  • Requirement

    Use session lock with pattern-hiding displays to prevent access and viewing of data after a period of inactivity.

  • Discussion

    Session locks are temporary actions taken when users stop work and move away from the immediate vicinity of the system but do not want to log out because of the temporary nature of their absences. Session locks are implemented where session activities can be determined, typically at the operating system level (but can also be at the application level). Session locks are not an acceptable substitute for logging out of the system, for example, if organizations require users to log out at the end of the workday.

    Pattern-hiding displays can include static or dynamic images, for example, patterns used with screen savers, photographic images, solid colors, clock, battery life indicator, or a blank screen, with the additional caveat that none of the images convey controlled unclassified information.

More Info

  • Title

    Session Lock

  • Domain

    Access Control

  • CMMC Level

    2

  • Related NIST 800-171 ID

  • Related NIST 800-53 ID

    AC-11;AC-11(1)

  • DoD Scoring Methodology Points

    1

  • Reference Documents

    • N/A

  • Further Discussion

    Session locks can be initiated by the user or, more fundamentally, enabled automatically when the system has been idle for a period of time, for example, five minutes. Session locks are a quick way to prevent unauthorized use of the systems without having a user log off. Minimum configuration requirements are left up to the organization to define.

    A locked session shows pattern-hiding information on the screen to mask the data on the display.

    Example

    You manage systems for an organization that stores, processes, and transmits CUI. You notice that employees leave their offices without locking their computers. Sometimes their screens display sensitive company information. You configure all machines to lock after five minutes of inactivity [a,b]. You also remind your coworkers to lock their systems when they walk away [a].

    Potential Assessment Considerations

    • Does the session lock hide previously visible information (e.g., replacing what was visible with a lock screen or screensaver that does not include sensitive information) [c]?
    • If session locks are not managed centrally, how are all computer users made aware of the requirements and how to configure them [a,b,c]?

NIST 800-171A Assessment Guidance

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