What Is Incident Response?
Incident Response (IR) is the methodology and process for handling cybersecurity incidents — from initial detection through full recovery. An effective IR capability minimizes damage, reduces recovery time and costs, and generates lessons learned to improve future defenses.
The NIST Incident Response Lifecycle
The NIST framework (SP 800-61) defines four phases:
1. Preparation
- Develop and maintain an incident response plan
- Build and train an incident response team
- Deploy detection and response tools (SIEM, EDR, SOAR)
- Establish communication channels and escalation procedures
- Conduct tabletop exercises and simulations
2. Detection and Analysis
- Identify potential incidents from alerts, user reports, or threat hunting
- Triage and validate: is this a true incident?
- Determine scope: what systems and data are affected?
- Classify severity and assign priority
- Document findings and preserve evidence
3. Containment, Eradication, and Recovery
- Contain: Isolate affected systems to prevent spread (network isolation, account disabling)
- Eradicate: Remove the threat (malware, backdoors, compromised credentials)
- Recover: Restore systems from clean backups, rebuild if necessary
- Verify systems are clean before returning to production
4. Post-Incident Activity
- Conduct a blameless post-mortem / lessons-learned review
- Document the incident timeline, impact, and response actions
- Identify improvements to prevent recurrence
- Update detection rules and response playbooks
- Report to stakeholders and regulators as required
Building an IR Team
An incident response team typically includes:
- IR Lead: Coordinates the response effort
- Security Analysts: Investigate and analyze the incident
- Forensics Specialists: Preserve and analyze digital evidence
- IT Operations: Execute containment and recovery actions
- Legal/Compliance: Advise on disclosure requirements
- Communications: Handle internal and external messaging
IR Metrics
Key metrics to track:
- MTTD (Mean Time to Detect) — How quickly incidents are identified
- MTTR (Mean Time to Respond) — How quickly incidents are contained
- Dwell time — How long threats persist before detection
- Incidents per month — Volume and trends over time