ISO 27001 A.5.27 - Learning from Information Security Incidents

Requirement

“Knowledge gained from information security incidents shall be used to strengthen and improve the information security controls.”

Plain-language meaning

The organization must turn incident experience into better controls, procedures, awareness, risk treatment, and response capability.

Why this matters

If incidents do not lead to improvement, the ISMS repeats the same failures. This control connects incident handling to performance evaluation and continual improvement.

Implementation guidance

1. Perform post-incident reviews for significant incidents and recurring minor incidents.
2. Capture root causes, failed controls, detection gaps, response delays, communication issues, evidence gaps, and recovery problems.
3. Create corrective actions with owners, due dates, evidence requirements, and closure review.
4. Feed lessons into risk assessment, control design, training, awareness, supplier review, and management review.
5. Use anonymized incident examples in awareness training where appropriate.

Audit guidance

Auditors should sample incidents and verify that learning was captured, translated into action, completed, and used to improve controls or procedures. If few incidents exist, auditors should test whether event reporting is actually working.

Evidence examples

Strong evidence

• Post-incident review records identify root causes and control failures.
• Corrective actions are tracked to closure with evidence.
• Lessons update procedures, controls, risk assessments, training, or supplier controls.
• Anonymized examples are used in awareness where appropriate.
• Incident trends are reported to management review.

Weak evidence

• Lessons learned meeting held but no actions recorded.
• Corrective actions closed without evidence.
• Training uses generic examples unrelated to actual incidents.
• No link to risk assessment or control improvement.
• The organization claims no incidents but has no event reporting evidence.

Common failures

Exam traps

• A.5.27 is about using knowledge to improve controls, not just documenting the incident.
• No incidents can be a warning sign if reporting is weak.
• Lessons can improve prevention, detection, response, evidence collection, and training.
• This links directly to Clauses 9 and 10.
• Anonymized case studies can support awareness, but confidentiality must be protected.

Related controls and concepts

• A.5.24 Information Security Incident Management Planning and Preparation
• A.5.26 Response to Information Security Incidents
• Internal Audit
• Management Review
• Corrective Action Tracker
• Risk Assessment

KB-ready summary

A.5.27 requires a controlled part of the incident-management lifecycle: The organization must turn incident experience into better controls, procedures, awareness, risk treatment, and response capability. In practice, this means defined criteria, assigned ownership, recorded decisions, operating evidence, and improvement links back into the ISMS.

Templates and checklists

• Incident Lessons Learned Register
• Corrective Action Tracker
• A.5.27 Audit Checklist