NIST SP 800-171 Rev. 3·Requirement 3.17.3·high·Component: System and Services Acquisition

What this control requires

This control requires establishing a process for identifying and addressing weaknesses in the supply chain and enforcing security requirements to protect against supply chain risks. It aims to limit the harm or consequences from events that impact the system, system components, or services, including vulnerabilities in hardware, software, firmware, and system development processes. This control supports the Supply Chain Risk Management capability within the System and Services Acquisition (3.17) family.
— NIST SP 800-171 Rev. 3, Requirement 3.17.3

In plain English

This control requires establishing a process for identifying and addressing weaknesses in the supply chain and enforcing security requirements to protect against supply chain risks. In practice, this means you can prove you impact 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 System and Services Acquisition, the assessor will trace your implementation back to the catalogue reference (Requirement 3.17.3) and look for objective evidence on the latest two assessment cycles.

How to implement

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.

Secure Development

Pipeline. Require code review, SAST (Semgrep / Snyk Code), SCA (Dependabot / Renovate), secret-scanning and IaC scanning in the merge pipeline.

Branch protection. Protected branches enforce reviews, signed commits and passing CI before merge; document the protection rules as the control evidence.

Vulnerability Management

Scanners. Pair an unauthenticated scanner (Nessus / Qualys / Tenable.io) for external surface with an authenticated agent for OS/library CVEs on every host.

SLA. Document remediation SLAs by CVSS / EPSS: critical 7 days, high 30 days, medium 90 days; report monthly trend to leadership.

Containers. Scan images in CI (Trivy / Grype / Snyk Container) AND at runtime; block deploys on critical findings without exception.

Operational checklist

  • Impact. Document the trigger, the owner and the cadence.
  • System. Document the trigger, the owner and the cadence.
  • Risk. Document the trigger, the owner and the cadence.
  • Security. Document the trigger, the owner and the cadence.
  • Policy. Document the trigger, the owner and the cadence.
  • Scope: management, software, hardware, firmware, security, system components, development, acquisition.

Evidence to collect

  • Policy Document. A signed and version-controlled policy / standard / procedure document.

Signed policy or standard documents the safeguard. Focus: Supply Chain Requirements and Processes.

Common pitfalls

  • Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.
  • CI security checks set to warn-only; the merge button is faster than the security feedback.
  • Scans that hit only the perimeter; missing authenticated scans of OS, runtime libs and base images so most CVEs are invisible.

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 riskpolicy managementsecure developmentsupply chain securityvulnerability management