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AC-2(12) AC · Access Control

Account Monitoring for Atypical Usage

LOW MODERATE ✓ HIGH
1 Overlay 5 Related Controls
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Requirements NIST SOURCE

Discussion (NIST Supplemental Guidance)

Atypical usage includes accessing systems at certain times of the day or from locations that are not consistent with the normal usage patterns of individuals. Monitoring for atypical usage may reveal rogue behavior by individuals or an attack in progress. Account monitoring may inadvertently create privacy risks since data collected to identify atypical usage may reveal previously unknown information about the behavior of individuals. Organizations assess and document privacy risks from monitoring accounts for atypical usage in their privacy impact assessment and make determinations that are in alignment with their privacy program plan.

Implementation Guidance

Engineering Interpretation

Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.

No engineering interpretation has been authored for AC-2(12) yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.

Assessment

NIST SP 800-53A REV 5.2.0

Assessment Objectives

  1. atypical usage for which to monitor system accounts is defined;
  2. personnel or roles to report atypical usage is/are defined;
  3. system accounts are monitored for <AC-02(12)_ODP[01] atypical usage>;
  4. atypical usage of system accounts is reported to <AC-02(12)_ODP[02] personnel or roles>.

Examine

[SELECT FROM: Access control policy; procedures addressing account management; system design documentation; system configuration settings and associated documentation; system monitoring records; system audit records; audit tracking and monitoring reports; privacy impact assessment; system security plan; privacy plan; other relevant documents or records].

Interview

[SELECT FROM: Organizational personnel with account management responsibilities; system/network administrators; organizational personnel with information security responsibilities].

Test

[SELECT FROM: Mechanisms implementing account management functions].

Overlays

Showing the OT/ICS overlay for the parent control AC-2 — see the AC-2(12) entries within each baseline below.

OT/ICS Overlay SP 800-82r3

NIST SP 800-82r3 Appendix F, Table 22. Blank baseline means the control/control enhancement is not selected in that initial OT baseline.

LOW

  • Base control: Included (matches standard baseline)

MODERATE

  • Base control: Included (matches standard baseline)
  • Included: (1) (2) (3) (4) (5) (13)
  • Added: (11) (12)

HIGH

  • Base control: Included (matches standard baseline)
  • Included: (1) (2) (3) (4) (5) (13)
  • Excluded: (11) (12)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for AC-2(12). This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.

Learn more about STIG/CCI integration →

Evidence

Potential Evidence — Derived

Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.

Policy

  • Access control policy
  • system security plan
  • privacy plan

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Mechanisms implementing account management functions

Other Records

  • procedures addressing account management
  • system monitoring records
  • system audit records
  • audit tracking and monitoring reports
  • privacy impact assessment
  • other relevant documents or records