NIST SP 800-171 Rev. 3·Requirement 3.10.2·high·Component: Physical Protection

What this control requires

This control requires monitoring physical access to the facility where systems process, store, or transmit Controlled Unclassified Information (CUI) to detect and respond to physical security incidents. It also mandates reviewing physical access logs at defined intervals and in response to specific events or suspicious activities to identify potential threats. This control supports the Physical Access Monitoring capability within the Physical Protection (3.10) family.
— NIST SP 800-171 Rev. 3, Requirement 3.10.2

In plain English

This control requires monitoring physical access to the facility where systems process, store, or transmit Controlled Unclassified Information (CUI) to detect and respond to physical security incidents. 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 Physical Protection, the assessor will trace your implementation back to the catalogue reference (Requirement 3.10.2) and look for objective evidence on the latest two assessment cycles.

How to implement

Physical Security

Inheritance. For cloud-only operations, inherit physical controls from the provider's SOC 2 / ISO 27001 report and document the inheritance in the SoA.

Policy Management

Docs. Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA.

Operational checklist

  • Access. Document the trigger, the owner and the cadence.
  • Information. Document the trigger, the owner and the cadence.
  • Response. Document the trigger, the owner and the cadence.
  • Protection. Document the trigger, the owner and the cadence.
  • Physical. Document the trigger, the owner and the cadence.
  • Scope: management, store, cui, security, physical access, response, protection.

Evidence to collect

  • Policy Document. A signed and version-controlled policy / standard / procedure document.
  • Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Signed policy or standard documents the safeguard. Focus: Monitoring Physical Access.

Common pitfalls

  • Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.

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.

Related controls in NIST SP 800-171 Rev. 3

References

Topics: governance risklogging monitoringphysical securitycontinuous monitoringpolicy management