Contents
📋 How to Conduct a Post-Incident Review (PIR)
A Post-Incident Review (PIR) is a structured process that occurs after a security incident has been contained and resolved. Its purpose is to understand what happened, how it happened, and what can be improved to prevent or respond more effectively next time.
🧠 “Never let a good incident go to waste.”
A PIR helps turn pain into progress.
🎯 Objectives of a PIR
- Analyse root causes and timeline of events
- Evaluate the effectiveness of detection and response
- Identify gaps in tools, processes, or communication
- Document lessons learned and apply them
- Ensure remediation and recovery steps were complete
- Define preventative actions for the future
🛠️ When to Conduct a PIR
| Trigger | Example |
|---|---|
| Major incident or data breach | Ransomware, credential compromise |
| High-impact but contained issue | Malware caught after lateral movement |
| Near-miss event | Attack failed due to luck, not controls |
| Recurring incident | Repeat phishing or misconfiguration issue |
Timing: Aim to conduct a PIR within 5–10 business days of incident closure, once stakeholders are available and all logs/artifacts are preserved.
🧩 Who Should Be Involved?
| Role | Responsibility |
|---|---|
| Incident Manager | Facilitates the PIR process |
| Security Analysts | Provide timeline, indicators, and tools used |
| IT/Infra Teams | Share host/network/system insights |
| Legal / Compliance | Document reporting, regulatory concerns |
| Management / Execs | Understand business impact |
| HR / Comms (if needed) | Help with internal/external messaging |
🔄 PIR Process Steps
1. Reconstruct the Incident Timeline
- When was it detected?
- How was it detected?
- What was the attacker’s path of access?
- What actions were taken by the responders?
Tip: Use SIEM logs, EDR timelines, and ticketing history to rebuild events.
2. Identify Root Cause and Contributing Factors
- Was it a misconfiguration?
- A user error?
- A failed detection or alert rule?
Use the 5 Whys or Fishbone (Ishikawa) diagram to drill down.
3. Assess Impact
- What data or systems were affected?
- Was anything exfiltrated or destroyed?
- What was the financial, reputational, or regulatory cost?
4. Evaluate Response Actions
- What went well (tools, communications, decision-making)?
- What could’ve been faster or more effective?
- Were playbooks followed properly?
5. Capture Lessons Learned
- Any visibility gaps or tooling deficiencies?
- Were key alerts missed or ignored?
- Did any manual steps cause delay?
6. Define Action Items
- Patch a vulnerability
- Update detection rules
- Add missing logging
- Conduct user training
- Update or test IR playbooks
Assign each action an owner and deadline.
🧾 Sample PIR Template Outline
- Summary of Incident
- Timeline of Events
- Root Cause Analysis
- Impact Assessment
- Response Evaluation
- Lessons Learned
- Action Items & Deadlines
- Sign-Off / Acknowledgements
✅ Best Practices
- Keep PIRs blameless but accountable – focus on systems and processes, not people
- Use PIRs to justify improvements (e.g. budget, tool upgrades, training)
- Store PIRs in a central knowledge base for future review
- Consider a “PIR as code” format using Markdown or Git-based tracking in mature teams
🧠 Summary
PIRs are vital not just for cleaning up after an incident—but for making sure the next one is caught earlier, handled faster, or prevented entirely. When done well, they build security maturity across teams.
🔎 “Incidents are inevitable. Failing to learn from them isn’t.”