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NIST SP 800-171 CUI Protection Center

03.01.02 — Access Enforcement

Read the official CUI requirement and assessment content, then use the separately labeled Bare Metal Cyber perspective to connect it to implementation, evidence, and sustained operation.

1Source controls
2Assessment objectives
3Assessment methods

03.01 — Access Control · NIST SP 800-171 Revision 3

Active
Official NIST requirement content

Security requirement

Enforce approved authorizations for logical access to CUI and system resources in accordance with applicable access control policies.

Official NIST discussion

Discussion

Access control policies control access between active entities or subjects (i.e., users or system processes acting on behalf of users) and passive entities or objects (i.e., devices, files, records, domains) in organizational systems. Types of system access include remote access and access to systems that communicate through external networks, such as the internet. Access enforcement mechanisms can also be employed at the application and service levels to provide increased protection for CUI. This recognizes that the system can host many applications and services in support of mission and business functions. Access control policies are defined in 03.15.01.

Bare Metal Cyber interpretation

Implementation perspective

Treat Access Enforcement as a CUI protection outcome 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.

  1. Confirm the requirement is in scope for the CUI system components, services, users, and external connections being assessed.
  2. Resolve every organization-defined parameter through an approved governance and tailoring process.
  3. Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
  4. Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
  5. Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.

Questions to ask

  • Which CUI assets, data flows, users, and services are protected by this 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
Official NIST SP 800-171A content

Assessment objectives and methods

Assessment objectives (2)
  1. SR-03.1.2.

    approved authorizations for logical access to CUI are enforced in accordance with applicable access control policies.

  2. SR-03.1.2.

    approved authorizations for logical access to system resources are enforced in accordance with applicable access control policies.

Examine

  • access control policy and procedures
  • procedures for access enforcement
  • system design documentation
  • system configuration settings
  • list of approved authorizations (i.e., user privileges)
  • system audit records
  • system security plan
  • other relevant documents or records

Interview

  • personnel with access enforcement responsibilities
  • system administrators
  • personnel with information security responsibilities
  • system developers

Test

  • mechanisms for implementing the access control policy
Official source-control relationships

Source NIST SP 800-53 controls

These controls are referenced by the official SP 800-171 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.

Source controlAC-3Open SP 800-53 control →
Source record

Authoritative sources

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.