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AC-4(8) AC · Access Control

Security and Privacy Policy Filters

LOW MODERATE HIGH
1 Overlay 0 Related Controls
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Requirements NIST SOURCE

Discussion (NIST Supplemental Guidance)

Organization-defined security or privacy policy filters can address data structures and content. For example, security or privacy policy filters for data structures can check for maximum file lengths, maximum field sizes, and data/file types (for structured and unstructured data). Security or privacy policy filters for data content can check for specific words, enumerated values or data value ranges, and hidden content. Structured data permits the interpretation of data content by applications. Unstructured data refers to digital information without a data structure or with a data structure that does not facilitate the development of rule sets to address the impact or classification level of the information conveyed by the data or the flow enforcement decisions. Unstructured data consists of bitmap objects that are inherently non-language-based (i.e., image, video, or audio files) and textual objects that are based on written or printed languages. Organizations can implement more than one security or privacy policy filter to meet information flow control objectives.

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(8) 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. security policy filters to be used as a basis for enforcing information flow control are defined;
  2. privacy policy filters to be used as a basis for enforcing information flow control are defined;
  3. information flows for which information flow control is enforced by security filters are defined;
  4. information flows for which information flow control is enforced by privacy filters are defined;
  5. one or more of the following PARAMETER VALUES is/are selected: {block; strip; modify; quarantine};
  6. security policy identifying actions to be taken after a filter processing failure are defined;
  7. privacy policy identifying actions to be taken after a filter processing failure are defined;
  8. information flow control is enforced using <AC-04(08)_ODP[01] security policy filter> as a basis for flow control decisions for <AC-04(08)_ODP[03] information flows>;
  9. information flow control is enforced using <AC-04(08)_ODP[02] privacy policy filter> as a basis for flow control decisions for <AC-04(08)_ODP[04] information flows>;
  10. <AC-04(08)_ODP[05] SELECTED PARAMETER VALUES> data after a filter processing failure in accordance with <AC-04(08)_ODP[06] security policy>;<AC-04(08)_ODP[05] SELECTED PARAMETER VALUES> data after a filter processing failure in accordance with <AC-04(08)_ODP[07] privacy policy>.

Examine

[SELECT FROM: Access control policy; information flow control policies; procedures addressing information flow enforcement; system design documentation; system configuration settings and associated documentation; list of security policy filters regulating flow control decisions; list of privacy policy filters regulating flow control decisions; system audit records; system security plan; privacy plan; other relevant documents or records].

Interview

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

Test

[SELECT FROM: Mechanisms implementing information flow enforcement policy; security and privacy policy filters].

Overlays

Showing the OT/ICS overlay for the parent control AC-4 — see the AC-4(8) 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(8). 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
  • list of security policy filters regulating flow control decisions
  • list of privacy policy filters regulating flow control decisions
  • system security plan
  • privacy plan

Configuration

  • system design documentation
  • system configuration settings and associated documentation

Testing

  • Mechanisms implementing information flow enforcement policy
  • security and privacy policy filters

Other Records

  • procedures addressing information flow enforcement
  • system audit records
  • other relevant documents or records