Post-Incident Activity in Incident Response

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Overview

The Post-Incident Activity phase is the final step in the Incident Response Process, as outlined by NIST 800-171 R2 and CMMC 2.0. This phase ensures that lessons learned from security incidents are documented, security posture is improved, and compliance requirements are met.

Objectives:

  • Conduct a group post-mortem analysis with the ESP and OSC Compliance Managers pertaining to the incident.
  • Identify gaps and improve security controls.
  • Update Incident Response Policies & Playbooks.
  • Retain logs and forensic data for compliance.
  • Implement security awareness improvements.

Post-Incident Review & Lessons Learned

Key Review Questions:

  • What was the root cause of the incident?
  • How effective were the containment and eradication measures?
  • Were security tools, like Microsoft Sentinel & Defender, used efficiently?
  • Were the incident response roles and responsibilities clearly understood?
  • What preventative measures can be put in place?

Conducting a Post-Mortem Analysis

  1. Gather Logs & Evidence
    • Collect logs from Microsoft Sentinel and Microsoft Defender for Endpoint.
    • Review Entra ID sign-in logs for anomalies.
    • Preserve forensic data for compliance (at least 365 days).
  2. Hold a Post-Mortem Meeting
    • Include Incident Response Team (IRT), SOC Analysts, and IT Security.
    • Review the attack timeline and mitigation efforts.
    • Assign action items to improve security posture.

Post-Incident Action Items

# Post-Incident
1 Create a follow-up report
2 Hold a lessons learned meeting (mandatory for major incidents, optional otherwise)

Updating Incident Response Policies & Playbooks

Key Documentation Updates:

  • Refine incident classification criteria based on real-world events.
  • Update Microsoft Sentinel playbooks to automate detection & response.
  • Enhance containment & eradication workflows for faster mitigation.

Example Playbook Improvement:

  1. Identify Gaps:
    • If a malware attack bypassed existing policies, update Microsoft Defender AV rules.
  2. Automate Detection:
    • Create Microsoft Sentinel analytics rules for similar attack patterns.
  3. Improve Response Speed:
    • Modify Incident Response SOPs to reduce response time.

Security Awareness & Training Improvements

Training Recommendations:

  • Conduct annual security awareness training.
  • Run phishing attack simulations using Microsoft Defender for Office 365.
  • Improve incident detection skills through Microsoft Security Workshops.

Tabletop Exercises:

  • Simulate ransomware, insider threat, and phishing scenarios.
  • Evaluate response times and adjust procedures as needed.
  • Ensure executives and IT staff understand escalation protocols.

Compliance & Log Retention Requirements

Log Retention Policies:

  • Retain Microsoft Sentinel logs for at least 90 days.
  • Archive Entra ID audit logs for forensic analysis.
  • Store forensic images for potential legal & regulatory investigations.

Incident Reporting Requirements:

Compliance Requirement Reporting Timeframe Reporting Authority
CUI Data Breach Within 72 hours Report to DoD via DIBNet
Microsoft Service Incident Immediate Open Azure Support Ticket
Internal Security Review Within 7 days IT Security Leadership

Note: The OSC is responsible for reporting incident involving CUI to the DoD within 72 hours of discovery using the following link: http://dibnet.dod.mil.

Continuous Improvement & Metrics

Key Performance Indicators (KPIs):

Metric Goal
Time to Detect (TTD) Reduce by 30%
Time to Contain (TTC) Reduce to under 1 hour for critical incidents
Time to Recover (TTR) Restore systems within 24 hours
False Positive Rate Reduce by 10% by refining SIEM rules

Improvement Recommendations:

  1. Implement real-time threat intelligence from Microsoft Defender.
  2. Enhance AI-driven automation for faster threat containment.

Conclusion

The Post-Incident Activity phase is critical for ensuring continuous security improvements and compliance. Organizations must leverage Microsoft Sentinel, Microsoft Defender for Endpoint, and Entra ID Security Logs to refine their incident response capabilities.

Next Steps:

  • Conduct a formal post-mortem for each significant incident.
  • Implement Microsoft Sentinel playbook improvements.
  • Strengthen security awareness training across the organization.

References