Incident Postmortem Template: Free Excel Download for Security Teams
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Key takeaways
- A postmortem turns an incident into durable improvements with a timeline, root cause, and tracked actions.
- This workbook covers 5 Whys analysis, contributing factors, six-dimension impact assessment, and a P1/P2/P3 action tracker.
- Run postmortems for SEV-1 and SEV-2 events within 5 business days of resolution.
- SecureSlate helps link corrective actions to controls and evidence.
Overview
Auditors and customers want to see that incidents lead to real change, not just a Slack thread that fades. A structured postmortem documents what happened, why, and what you fixed.
What makes it useful
- Incident summary: ID, title, detection and resolution times, duration, and severity.
- Chronological timeline: Timestamped events with systems, people, and evidence sources.
- Root cause analysis: 5 Whys plus contributing factors across technical, process, people, and third-party dimensions.
- Impact assessment: Customer, data, financial, reputational, operational, and regulatory impact.
- Corrective actions: Priority-coded tracker with owners, due dates, and status.
Download the template
- Download: Incident Postmortem (XLSX)
Complete within 5 business days while details are fresh. Share a blameless draft with participants before finalizing.
Tab-by-tab walkthrough
Overview and Version & Approval
Document control and sign-off. Link to the parent incident ticket.
Incident Summary
Fill Incident ID, title, severity, detection time, resolution time, and total duration. One-paragraph executive summary of what happened and customer impact.
Timeline
Row per event: UTC timestamp, event type (Detection, Escalation, Containment, Communication, Eradication, Recovery), description, systems involved, and source (SIEM, ticket, Slack). Pull from your IR war room channel and ticketing system.
Root Cause Analysis
Document contributing factors in four buckets, then work through 5 Whys to reach the root cause. Avoid stopping at "human error" without systemic fixes.
Impact Assessment
Score impact across six dimensions with estimated cost where possible. Supports breach notification and insurance discussions.
Corrective Actions
Log every action with Priority (P1 Critical, P2 High, P3 Medium), Category, Owner, Due Date, Status, and evidence link. P1 items should close within 30 days.
How to use it as audit evidence
| Auditor question | Where to answer |
|---|---|
| Did you analyze the incident? | Root Cause Analysis tab |
| What was the blast radius? | Impact Assessment tab |
| What did you fix? | Corrective Actions with closed tickets |
| Was response timely? | Timeline with timestamps |
Store finalized postmortems in your evidence library and reference them in your IR plan lessons learned log.
Common mistakes
- Timeline built from memory instead of log exports
- Root cause stops at a person instead of a control gap
- Corrective actions with no owner or due date
- Postmortem completed but actions never verified in the next audit period
How SecureSlate helps
SecureSlate tracks remediation tasks, maps them to controls, and keeps post-incident evidence organized for audits and customer reviews.
FAQ
Which incidents need a postmortem?
At minimum all SEV-1 and SEV-2 events. Many teams also postmortem near-misses that could have been SEV-1.
Should postmortems be blameless?
Yes. Focus on systems and process gaps. HR matters are handled separately.
How long should corrective actions take?
P1 within 30 days, P2 within 60 days, P3 within 90 days. Adjust based on risk.
Disclaimer (legal note)
This article is for general information only and is not legal, regulatory, or professional advice. Requirements vary by framework, industry, and jurisdiction. Consult qualified advisors for your specific obligations.
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