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AC-4(7) AC · Access Control

One-way Flow Mechanisms

LOW MODERATE HIGH
1 Overlay 0 Related Controls
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Requirements NIST SOURCE

Enforce one-way information flows through hardware-based flow control mechanisms.

Discussion (NIST Supplemental Guidance)

One-way flow mechanisms may also be referred to as a unidirectional network, unidirectional security gateway, or data diode. One-way flow mechanisms can be used to prevent data from being exported from a higher impact or classified domain or system while permitting data from a lower impact or unclassified domain or system to be imported.

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-4(7) 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. one-way information flows are enforced through hardware-based flow control mechanisms.

Examine

[SELECT FROM: Access control policy; information flow control policies; procedures addressing information flow enforcement; system design documentation; system configuration settings and associated documentation; system hardware mechanisms and associated configurations; system audit records; 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: Hardware mechanisms implementing information flow enforcement policy].

Overlays

Showing the OT/ICS overlay for the parent control AC-4 — see the AC-4(7) 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)
  • Included: (4)

STIGs & CCIs

No STIG checks or CCI mappings are currently loaded for AC-4(7). 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
  • information flow control policies
  • system security plan

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Hardware mechanisms implementing information flow enforcement policy

Other Records

  • procedures addressing information flow enforcement
  • system hardware mechanisms and associated configurations
  • system audit records
  • other relevant documents or records