Building an Effective Incident Response Plan for CMMC Compliance

Every defense contractor working toward CMMC certification knows that preparing policies and procedures is only half the battle. One of the most scrutinized and often underestimated requirements is having a clear, actionable Incident Response Plan (IRP). For many small and mid-sized businesses in the Defense Industrial Base (DIB), this can feel overwhelming. The good news is that with the right approach, your IRP can be both manageable and effective.

Why Incident Response Matters in CMMC

CMMC 2.0 emphasizes not just preventing breaches but also proving you can detect, respond, and recover when something goes wrong. DFARS 252.204-7012 already requires reporting cyber incidents within 72 hours. If your plan doesn’t spell out how you’ll meet that timeline, you’re leaving yourself and your contracts at risk.

An effective IRP demonstrates to auditors and the DoD that your organization can contain threats quickly, protect Controlled Unclassified Information (CUI), and reduce the impact of an attack.

Key Elements of an Incident Response Plan

When building your plan, focus on these four pillars:

1. Preparation

   • Define what qualifies as an incident (phishing, malware, insider threat, unauthorized access, etc.).

   • Identify your IR team roles who does what when an alert fires?

   • Ensure you have the right monitoring tools, log management, and reporting templates.

2. Detection and Analysis

   • Set up procedures for identifying suspicious activity through SIEM alerts, intrusion detection, or user reports.

   • Document escalation paths (e.g., when does IT escalate to leadership or legal?).

   • Include criteria for severity levels so you can prioritize responses.

3. Containment, Eradication, and Recovery

   • Define short-term containment (isolate the affected system) vs. long-term (apply patches, reset credentials).

   • Lay out steps for restoring systems from clean backups.

   • Keep recovery timelines realistic and aligned with contractual obligations.

4. Post-Incident Review

   • Conduct a lessons-learned session after each incident.

   • Update policies, controls, and training to prevent recurrence.

   • Document everything, this will become part of your evidence package for a CMMC audit.

Common Mistakes to Avoid

• Treating IR as an IT-only issue. Legal, HR, and management must also play a role.

• Not testing the plan. A tabletop exercise at least once a year is essential.

• Overcomplicating the process. Your plan should be easy to follow under stress, think checklists, not novels.

Practical Tips for Small Businesses

• Use templates as a starting point (NIST 800-61 has a solid baseline).

• Lean on your MSP/MSSP for monitoring and triage if you don’t have in-house capability.

• Integrate your IRP with your System Security Plan (SSP) and Plan of Action & Milestones (POA&M) to ensure consistency.

• Train employees regularly phishing simulations are a cost-effective way to improve detection.

Final Thoughts

An effective Incident Response Plan isn’t just a CMMC checkbox it’s a critical defense measure that could save your business from reputational damage, financial loss, or lost contracts. By keeping it clear, actionable, and aligned with CMMC requirements, you’ll not only satisfy auditors but also build real resilience into your operations.