NIST SP 800-171 Rev. 3 3.1.22 — Publicly Accessible Content

What this control requires

This control ensures that authorized individuals are trained to prevent the inclusion of Controlled Unclassified Information (CUI) in publicly accessible content. It also requires regular reviews of publicly accessible systems to identify and remove any CUI that may have been inadvertently published. This control supports the Content Management System capability within the Access Control (3.1) family.

In plain English

This control ensures that authorized individuals are trained to prevent the inclusion of Controlled Unclassified Information (CUI) in publicly accessible content. In practice, this means you can prove you access management-level controls on a defined cadence.

Why it matters

DoD contractors and their subcontractors must implement all 100 SP 800-171 requirements to keep CUI handling contracts. Gaps are scored against the SPRS scoring methodology; below a 110-point starting score, each unmet requirement deducts points and a below-threshold score can disqualify a bid.

This control is rated high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

What an auditor looks for

A C3PAO conducting a CMMC Level 2 assessment uses NIST SP 800-171A objectives. They expect a System Security Plan (SSP), Plan of Action & Milestones (POA&M) for any gaps, and objective evidence (configurations, ticket records, training records) for every requirement.

Within Access Control, the assessor will trace your implementation back to the catalogue reference (Requirement 3.1.22) and look for objective evidence on the latest two assessment cycles.

How to implement

1. Write a short policy stating intent, scope and named owner.
2. Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy.
3. Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it.
4. Review on a documented cadence and capture the review in the risk register or compliance tracker.

Operational checklist

• Access. Document the trigger, the owner and the cadence.
• Information. Document the trigger, the owner and the cadence.
• Access Control. Document the trigger, the owner and the cadence.
• Publicly. Document the trigger, the owner and the cadence.
• Authorized. Document the trigger, the owner and the cadence.
• Scope: management, cui, accessible content, individuals, access control.

Evidence to collect

• Identity Scan. IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in.
• Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Publicly Accessible Content.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• NIST SP 800-53 Rev. 5 AC-22 — Publicly Accessible Content
• CIS Controls v8 6.8 — Define and Maintain Role-Based Access Control
• ISO/IEC 27001:2022 A.5.16 — Identity management
• BSI C5:2020 PS-04 — Physical site access control
• SOC 2 (2017 TSC) CC6.1 — Logical Access Controls

Related controls in NIST SP 800-171 Rev. 3

• Requirement 3.1.6 — Least Privilege - Privileged Accounts
• Requirement 3.1.1 — Account Management
• Requirement 3.1.4 — Separation of Duties
• Requirement 3.1.7 — Least Privilege - Privileged Functions
• Requirement 3.1.11 — Session Termination
• Requirement 3.2.2 — Role-Based Training

References

• NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
• Catalogue identifier: Requirement 3.1.22

Topics: governance riskidentity accessidentity managementaccess reviewprivileged access