CMMC Navigatorby Foxx Cyber Bedrock CMMC

↑↓ to move, Enter to open, Esc to close. Try 3.5.3, AC.L2-3.1.1, MFA or unmarked.

3.1.10Lock idle screens

Screens lock themselves after a set idle period and hide what was on them.

The requirement, verbatim

NIST SP 800-171 Rev. 2 · 3.1.10

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

Requirement 3.1.10, practice name in the CMMC assessment guide: Session Lock.

NIST's 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.

NIST SP 800-171 Rev. 2, discussion under 3.1.10. Whitespace normalised; wording unchanged.

Assessment objectives

An assessor decides each of these separately. The requirement is met only when every objective is.

  1. [a] the period of inactivity after which the system initiates a session lock is defined
  2. [b] access to the system and viewing of data is prevented by initiating a session lock after the defined period of inactivity
  3. [c] previously visible information is concealed via a pattern-hiding display after the defined period of inactivity

NIST SP 800-171A, determination statements for 3.1.10.

For assessors: examine, interview, test

NIST SP 800-171A names what an assessor may examine, whom they may interview, and what they may test for this requirement. Assessors select from these lists; they are not a checklist of everything you must produce.

Examine
  • Access control policy
  • procedures addressing session lock
  • system design documentation
  • system configuration settings and associated documentation
  • system security plan
  • system audit logs and records
  • other relevant documents or records
Interview
  • Personnel with information security responsibilities
  • system developers
  • system or network administrators
Test
  • Mechanisms implementing access control policy for session lock

NIST SP 800-171A, potential assessment methods and objects for 3.1.10.

Evidence

No evidence examples are published for this requirement yet. The objectives above are what an assessor checks; evidence is whatever shows each one is true in your environment, dated and kept with your system security plan.

Scoring weight

Worth 1 point. Not meeting this requirement subtracts 1 from your 110-point SPRS score.

DoD NIST SP 800-171 Assessment Methodology v1.2.1 weighting, as carried in the Bedrock scoring table. The score starts at 110 and subtracts the weight of every requirement not met.

In Rev. 3

Rev. 2 is what your contract requires today. A standing DoD class deviation keeps Rev. 2 in force; NIST has published Rev. 3, but it is not adopted for contracts. In Rev. 3 this requirement is reworded: 03.01.10 Device Lock. It gains organization-defined parameters.

See the Rev. 2 and Rev. 3 wording word by word, or start with the status page.

Where this page's facts come from
Requirement text
bedrock-cmmc-api@89b8e8e:migrations/004_reference_requirements.sql#Requirement.basicRequirement@rev2
Discussion
bedrock-cmmc-api@89b8e8e:migrations/004_reference_requirements.sql#Requirement.discussion@rev2
Practice name
bedrock-cmmc-api@89b8e8e:migrations/004_reference_requirements.sql#Requirement.title@rev2 (CMMC Assessment Guide practice name)
Objectives
bedrock-cmmc-api@89b8e8e:migrations/005_reference_objectives.sql#AssessmentObjective.description@rev2
Examine, interview, test
bedrock-cmmc-api@89b8e8e:migrations/005_reference_objectives.sql#AssessmentObjective.description@rev2 ({examineGuidance, interviewGuidance, testGuidance})
Level
bedrock-cmmc-api@89b8e8e:migrations/021_fix_level1_requirements.sql#Requirement.cmmcLevel@rev2
Weight
bedrock-cmmc-api@89b8e8e:internal/cmmc/requirement_values.go#requirementValues (DoD AM v1.2.1 / eMASS L2 template v3.8)
Rev. 3 mapping
bedrock-cmmc-api@89b8e8e:docs/reference/nist-800-171-rev3/normalized/r2_r3_transition_map.json#r2_to_r3
Plain-language title and summary
editorial/CMMC Navigator.dc.html#RAW (Foxx Cyber editorial)