Security requirement
- a.Enforce information flow control using [Organization-defined: organization-defined security policy filters] as a basis for flow control decisions for [Organization-defined: organization-defined information flows].
- b.[Organization-defined: SELECTED PARAMETER VALUE(S)] data after a filter processing failure in accordance with [Organization-defined: organization-defined security policy].
Discussion
Security policy filters for data structures check for maximum file lengths, maximum field sizes, and data/file types for structured and unstructured data. Security policy filters for data content 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 criticality or sensitivity of information conveyed by the data or the flow enforcement decisions. Unstructured data consists of bitmap objects that are inherently non-language-based (e.g., image, video, or audio files) and textual objects that are based on written or printed languages. This requirement enhances SP 800-171 requirement 03.01.03.
Tailoring decisions required
Resolve these values through the governing organization’s approved tailoring and risk-management process before declaring the requirement implemented.
Protection strategies supported
These classifications are carried from the official SP 800-172 OSCAL record and help explain the enhanced requirement’s defensive purpose.
Implementation perspective
Treat Security Policy Filters as an enhanced CUI protection outcome for elevated threat conditions that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to approved identities, least privilege, remote access, information flow, and the full account lifecycle.
- Confirm the federal agency selected this enhanced requirement for the critical program or high-value asset and identify the CUI system components, services, users, and external connections in scope.
- Resolve every organization-defined parameter through an approved governance and tailoring process.
- Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
- Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
- Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.
Questions to ask
- Which critical-program or high-value-asset CUI, data flows, users, and services are protected by this enhanced requirement?
- Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
- Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
- What change, incident, or threshold should trigger reassessment?
Evidence and validation
- access authorization and approval records
- account inventories and entitlement exports
- access review results
- authentication and authorization logs
Common failure patterns
- CUI access that exceeds mission need
- shared or orphaned accounts
- remote access paths outside the approved boundary
- access reviews that cannot be reconciled to deployed permissions
Assessment objectives and methods
Assessment objectives (2)
- a.
information flow control is enforced using [Organization-defined: organization-defined security policy filters] as a basis for flow control decisions for [Organization-defined: organization-defined information flows] .
- b.
[Organization-defined: SELECTED PARAMETER VALUE(S)] data after a filter processing failure in accordance with [Organization-defined: organization-defined security policy].
Examine
- 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
- system audit records
- system security plan
- other relevant documents or records
Interview
- System/network administrators
- organizational personnel with information security responsibilities
- system developers
Test
- Mechanisms implementing information flow enforcement policy
- security policy filters
Source NIST SP 800-53 controls
These controls are referenced by the official SP 800-172 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.
Authoritative sources
- NIST SP 800-172 Revision 3 official publication ↗
- NIST SP 800-172A Revision 3 official publication ↗
- NIST OSCAL Content release used for this import ↗
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.