CMMC reshapes how defense contractors secure CUI. One of the most critical components of CMMC compliance is incident response (IR)—the ability to detect, respond to, and recover from cybersecurity incidents while meeting strict reporting and documentation requirements.

Under the final CMMC rule, contractors at Level 2 and above must implement formalized IR policies, procedures, and continuous monitoring capabilities to maintain compliance. Without a well-structured IR plan, organizations risk non-compliance, loss of contract eligibility, and significant security breaches.

CMMC Incident Response Requirements

Incident response falls under the IR (Incident Response) domain in NIST 800-171. At CMMC Level 2, organizations must comply with several IR-related practices that focus on preparing for, detecting, analyzing, containing, and recovering from cybersecurity incidents. Some of the key IR requirements in CMMC include:

Develop and Maintain an Incident Response Plan (IR-3.06.05)

Organizations must have a formal, documented IRP that outlines how to handle security incidents.
The plan should define roles, responsibilities, escalation procedures, and containment strategies.

Test and Improve the IR Plan Regularly (IR-3.06.03)

Incident response capabilities must be tested through simulations, tabletop, or red team exercises.
Lessons learned from tests must be used to update and refine IR policies.

Track and Document Security Incidents (IR-3.03.05)

Every security incident must be recorded in an incident tracking system, including event timelines, affected systems, and remediation actions.

Report Security Incidents to the DoD (IR-3.06.02)

Contractors handling CUI must report incidents to the DoD within 72 hours via the Defense Industrial Base (DIB) Cybersecurity Program.
Reports must include details on the nature of the attack, affected data, and containment measures.

Conduct Post-Incident Reviews (IR.-3.03.05)

After resolving an incident, organizations must perform a root cause analysis to identify security gaps and prevent recurrence.
Lessons learned must be integrated into security policies and IR training.

Building a CMMC-Compliant Incident Response Plan

A compliant incident response plan will cover four primary pillars: preparation, detection and analysis, containment and eradication, and recovery:

Preparation: Establishing Readiness

Policy Development: Organizations should develop an Incident Response Policy that aligns with CMMC and NIST 800-61 (Computer Security Incident Handling Guide).
Team Formation: A dedicated Incident Response Team (IRT) should be established, with members assigned roles such as incident commander, forensic analyst, and containment specialist.
Incident Response Playbooks: Playbooks should be developed and cover insider threats, phishing attacks, ransomware, and APTs (among other threats).
Tabletop Exercises: Regular simulation drills ensure teams are ready to respond effectively.

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Detection and Analysis: Identifying and Assessing Incidents

SIEM and Log Monitoring: Security Information and Event Management (SIEM) platforms like Splunk, Microsoft Sentinel, and Elastic Security should aggregate and analyze logs from firewalls, intrusion detection systems (IDS), and endpoint security tools.
Threat Intelligence Integration: Organizations should integrate real-time threat intelligence feeds from CISA, the DoD Cyber Crime Center (C3), and the MITRE ATT&CK framework.
Incident Classification: Incidents should be categorized based on severity levels, like Low (policy violations, unsuccessful phishing attempts), High (compromised credentials or malware infections), and critical (immediate CUI threats).

Containment and Eradication

Once a threat is identified, there must be quick and total action to contain and eradicate it. Containment typically comes first, and companies must be able to work fast to keep threats from causing further damage:

Immediate containment actions include:

For Network Breaches: Disable compromised accounts, isolate affected devices, and block malicious IP addresses.
For Ransomware Attacks: Immediately disconnect infected machines, disable lateral movement, and assess backup integrity.
For Insider Threats: Restrict user access, log all privileged account activity, and initiate HR/legal reviews.

Eradication measures include:

For Malware Infections: Perform full-system scans and reimage affected devices.
For Cloud-based Attacks: Audit API calls, reset compromised tokens, and verify encryption controls.
For Supply Chain Threats: Conduct third-party security audits and rotate shared credentials.

Recovery: Restoring Normal Operations

CMMC expects that you have controls and policies to quickly restore security systems and ensure that data systems are operational after an incident. Additionally, an organization is expected to conduct an investigation using data and forensics to understand the threat and mitigate it in the future.

Some of these practices include:

System Restoration: Organizations must ensure that backups are secure, validated, and restorable before reintroducing affected systems into the network.
Forensic Investigation: A detailed forensic report should document attack vectors, affected data and systems, corrective actions, and mitigation recommendations.
Reporting to the DoD: Contractors must submit incident reports via DIBNet within 72 hours. For major breaches, organizations may need to coordinate with the FBI Cyber Task Force or CISA.

Ensuring Long-Term Compliance

Organizations should implement continuous monitoring and proactive threat hunting to detect and mitigate threats before they escalate. Deploying endpoint detection and response (EDR) tools such as CrowdStrike Falcon, Microsoft Defender for Endpoint, or SentinelOne enhances visibility and response capabilities.

Regular security awareness training is also essential, ensuring employees stay informed about incident reporting, phishing tactics, and insider threat detection. Conducting red team exercises can further assess their ability to respond to simulated cyberattacks.

Additionally, organizations should review and update their incident response (IR) plans annually to adapt to evolving threats and CMMC updates. After every major incident, post-mortem reviews should be conducted to identify weaknesses and strengthen security policies.

Trust Continuum GRC for Your Continuing CMMC Compliance

A well-executed incident response plan is a requirement for CMMC compliance and an essential defense mechanism against cyber threats. Organizations implementing continuous monitoring, structured response processes, and proactive security measures will meet CMMC standards and enhance their overall security resilience.

Continuum GRC is a cloud platform that stays ahead of the curve, including support for all certifications (along with our sister company and assessors, Lazarus Alliance).

We are the only FedRAMP and StateRAMP-authorized compliance and risk management solution worldwide.

Continuum GRC is a proactive cyber security® and the only FedRAMP and StateRAMP-authorized cybersecurity audit platform worldwide. Call 1-888-896-6207 to discuss your organization’s cybersecurity needs and learn how we can help protect its systems and ensure compliance.

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CMMC and Incident Response: Building a Compliant Security Plan