NIST SP 800-171 Rev. 3·Requirement 3.6.3·high·Component: Incident Response

What this control requires

This control requires testing the effectiveness of the incident response capability at defined intervals. Testing methods may include checklists, tabletop exercises, and simulations to identify weaknesses and assess the impact on operations, assets, and individuals. Both qualitative and quantitative data are used to evaluate incident response processes. This control supports the Incident Response Testing Mechanism capability within the Incident Response (3.6) family.
— NIST SP 800-171 Rev. 3, Requirement 3.6.3

In plain English

This control requires testing the effectiveness of the incident response capability at defined intervals. In practice, this means you can prove you response 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 Incident Response, the assessor will trace your implementation back to the catalogue reference (Requirement 3.6.3) and look for objective evidence on the latest two assessment cycles.

How to implement

Incident Response

Runbook. Maintain a runbook keyed by incident type with named roles (IC, comms, scribe), an out-of-band comms channel, and a 72-hour timeline for external notification.

Tabletop. Run a quarterly tabletop exercise (ransomware, insider, supply-chain) and feed gaps back into the runbook.

Code Review Testing

Pipeline. Require at least one human reviewer plus passing CI (lint, type, unit, security scan) before merge — protected branches enforce this.

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

  • Response. Document the trigger, the owner and the cadence.
  • Impact. Document the trigger, the owner and the cadence.
  • Incident. Document the trigger, the owner and the cadence.
  • Risk. Document the trigger, the owner and the cadence.
  • Policy. Document the trigger, the owner and the cadence.
  • Scope: management, checklists, tabletop exercises, assets, individuals, response, code, operations.

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: Incident Response Testing.

Common pitfalls

  • Runbooks that name a role but no person, or list a paging channel that no longer exists.
  • 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 riskincident responsecode review testingpolicy management