← AC-21
AC-21(1) AC · Access Control

Automated Decision Support

LOW MODERATE HIGH
1 Overlay 0 Related Controls
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Requirements NIST SOURCE

Employ [automated mechanisms] to enforce information-sharing decisions by authorized users based on access authorizations of sharing partners and access restrictions on information to be shared.

Discussion (NIST Supplemental Guidance)

Automated mechanisms are used to enforce information sharing decisions.

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-21(1) 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. automated mechanisms employed to enforce information-sharing decisions by authorized users are defined;
  2. <AC-21(01)_ODP automated mechanisms> are employed to enforce information-sharing decisions by authorized users based on access authorizations of sharing partners and access restrictions on information to be shared.

Examine

[SELECT FROM: Access control policy; procedures addressing user-based collaboration and information sharing (including restrictions); system design documentation; system configuration settings and associated documentation; system-generated list of users authorized to make information-sharing/collaboration decisions; system-generated list of sharing partners and access authorizations; system-generated list of access restrictions regarding information to be shared; system security plan; other relevant documents or records].

Interview

[SELECT FROM: System/network administrators; organizational personnel with information security responsibilities; system developers].

Test

[SELECT FROM: Automated mechanisms implementing access authorizations supporting information-sharing/user collaboration decisions].

Overlays

Showing the OT/ICS overlay for the parent control AC-21 — see the AC-21(1) 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

Not applicable at this tier.

MODERATE

  • Base control: Included (matches standard baseline)

HIGH

  • Base control: Included (matches standard baseline)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for AC-21(1). 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

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Automated mechanisms implementing access authorizations supporting information-sharing/user collaboration decisions

Other Records

  • procedures addressing user-based collaboration and information sharing (including restrictions)
  • system-generated list of users authorized to make information-sharing/collaboration decisions
  • system-generated list of sharing partners and access authorizations
  • system-generated list of access restrictions regarding information to be shared
  • other relevant documents or records