Key takeaways
- Use lessons from incidents to strengthen your controls.
- Incidents are expensive lessons.
- Start here: run a short post-incident review for significant incidents.
Purpose
Use lessons from incidents to strengthen your controls.
Requirement
Requirement summaryKnowledge gained from information security incidents shall be used to strengthen and improve the information security controls.
Why it matters
Incidents are expensive lessons. Capturing what you learned prevents the same thing happening again.
How to implement
- Run a short post-incident review for significant incidents.
- Identify root causes, not just symptoms.
- Create actions to improve controls and track them to completion.
- Share lessons with relevant teams and update awareness content.
What evidence you need to provide
Here is what you will typically need to provide for Annex A 5.27. It does not matter which system it lives in: a document, screenshot or export is fine.
Documents to have ready
- Your process for reviewing incidents afterwards (lessons learned).
- Your Statement of Applicability (SoA: the list of all 93 controls showing which you use and why) with A.5.27 marked as used or not used, a short reason, and its current status.
Records and examples to show
- Notes from post-incident reviews, including the root cause.
- Proof that follow-up actions happened, such as updated training or new controls.
Things you should be able to show or explain
- Be able to explain how lessons are shared with the team.
How much to show: Two or three recent significant incidents and what was learned.
Common mistakes
- Same incident keeps happening.
- Lessons noted but never acted on.
- Reviews that blame individuals rather than fix processes.
- Actions raised but never closed.
- Tip: Hold a blameless post-incident review.
Policies & documents to have
- Incident Response Plan
FAQ
Is A.5.27 mandatory?
Annex A controls are not automatically mandatory. You must consider every control and record in your Statement of Applicability whether it applies and why. In practice, most organisations include this one.
What will I need to show for A.5.27?
Be ready to explain how the control works in your organisation and to provide things like: Your process for reviewing incidents afterwards (lessons learned)…