ISO 27001:2022 Annex A 5.27 Learning from information security incidents

In this guide, I will show you exactly how to implement ISO 27001 Annex A 5.27 and ensure you pass your audit. You will get a complete walkthrough of the control, practical implementation examples, and access to the ISO 27001 templates and toolkit that make compliance easy.

I am Stuart Barker, an ISO 27001 Lead Auditor with over 30 years of experience conducting hundreds of audits. I will cut through the jargon to show you exactly what changed in the 2022 update and provide you with plain-English advice to get you certified.

Key Takeaways: ISO 27001 Annex A 5.27 Learning from Information Security Incidents

ISO 27001 Annex A 5.27 requires that knowledge gained from information security incidents be used to strengthen and improve existing security controls. This is the “Learning” phase of the incident management lifecycle and is a vital component of the Continual Improvement principle that defines the ISO 27001 standard. This preventive control ensures that an organization doesn’t just “fix” a problem, but analyses the Root Cause to ensure the same incident (or similar ones) cannot happen again.

• It is part of the overall incident management process
• It relies on root cause analysis

Core requirements for compliance include:

• Mandatory Post-Incident Review (PIR): For every significant incident, you must conduct a formal review to document what happened, how the team responded, and what could be done differently next time.
• Root Cause Analysis (RCA): You must move beyond the “symptom” (e.g., a virus infection) to find the “cause” (e.g., an unpatched server or lack of staff training). Methodologies like the 5 Whys or Fishbone diagrams are recommended.
• Knowledge Integration: Insights gained from incidents must lead to tangible changes, such as updating your Risk Assessment, revising policies, or modifying technical configurations.
• Evidence Retention: You must maintain a formal “Lessons Learned” record. This document serves as proof of compliance and a resource for future incident response.
• Stakeholder Communication: Relevant findings should be shared with the wider team. Anonymized incident examples (e.g., a real phishing attempt) are highly effective tools for Security Awareness Training.

Audit Focus: Auditors will look for “The Learning Loop”:

1. Corrective Action Link: “Show me your incident log from last quarter. Now show me your Corrective Action Log (Clause 10.2). Can you prove that the root cause of this major incident was addressed and closed?”
2. Depth of Analysis: “For your last malware infection, did you just run an antivirus scan, or did you perform a Root Cause Analysis to find out how it bypassed your filters?”
3. Measurable Improvement: “Can you show me a policy or technical control that was updated specifically as a result of a lesson learned from a past incident?”

The 5 Whys: RCA Example (Audit Prep):

Level	Question	Answer (The Chain)	ISO 27001:2022 Control
The Problem	What happened?	Ransomware infected the server.	Annex A 5.24
Why 1	How did it get in?	An admin clicked a phishing link.	Annex A 7.22
Why 2	Why did the link work?	The email filter didn’t catch the malicious URL.	Annex A 8.13
Why 3	Why was it missed?	The filter’s threat definitions were 3 days old.	Annex A 8.8
Why 4	Why were they old?	The auto-update service crashed on Friday.	Annex A 8.14
Why 5 (Root)	True Cause?	No monitoring alerts on the update server.	Annex A 5.27

What is ISO 27001 Annex A 5.27?

ISO 27001 Annex A 5.27 is Learning From Information Security Incidents and is about learning from information security incidents so that they do not happen again and so that information security is improved.

ISO 27001 Annex A 5.27 specifically is an ISO 27001 control that requires an organisation to learn from information security events to improve.

ISO 27001 Annex 5.27 Purpose

ISO 27001 Annex A 5.27 is a preventive control and it’s purpose is to ensures the reduction in the likelihood or consequences of future incidents. By analysing and understanding what went wrong and why, organisations can prevent similar incidents from happening in the future or reduce their impact. This is continual improvement and a core principle of the ISO 27001 standard.

ISO 27001 Annex 5.27 Definition

ISO 27001 defines ISO 27001 Learning From Information Security Incidents as:

Knowledge gained from information security incidents should be used to strengthen and improve the information security controls.

ISO 27001:2022 Annex A 5.27 Learning from information security incidents

Watch the ISO 27001 Annex A 5.27 Tutorial

In this video I show you how to implement ISO 27001 Annex A 5.27 and how to pass the audit.

ISO 27001 Annex A 5.27 Podcast

In this episode: Lead Auditor Stuart Barker and team do a deep dive into the ISO 27001 Annex A 5.27 Learning From Information Security Incidents. The podcast explores what it is, why it is important and the path to compliance.

ISO 27001 Annex A 5.27 Implementation Guidance

An information security incident is an event that could potentially have a negative impact on the confidentiality, integrity, or availability of information. The consequences of an incident can vary depending on the nature of the incident, the systems and data affected, and the organisations response.

As part of your incident management you are going to implement a step that looks at learning from incidents. You will consider this documented process and how you will analyse incidents, identify the root cause and then make decisions on corrective actions as required.

1. Conduct a root cause analysis

Once an incident has occurred and been corrected you would then do a root cause analysis (RCA) to investigate why it happened and the underlying cause. The purpose of determining the cause is to ensure that it does not happen again.

2. Decision on next steps

Once the root cause has been identified, and there may be more than one, a decision will be made on what actions to take. The decision will be based on risk management and is a risk based decision that will be approved and overseen by the management review team. If the decision is to accept the risk and take no action, then this would be recorded in the risk register and if the decision is to take action to mitigate the risk, then this would be added to the corrective actions log and managed as a continuous improvement.

3. Keep records of lessons learnt

The root cause and the decisions made on next steps should be formally documented and retained. This is a valuable resource for future enhancements as well as for audit purposes.

4. Monitor effectiveness

Lessons learned and the improvements that have been made should be monitored to ensure that they are effective. This is usually done via the process of independent internal audit.

How to implement ISO 27001 Annex A 5.27

ISO 27001 Annex A 5.27 Implementation Checklist

ISO 27001 Learning From Information Security Incidents Implementation Checklist

1. Establish a clear incident review process

Challenge

Lack of defined steps for post-incident analysis, leading to inconsistent or missed learning opportunities.

Solution

Develop and document a formal procedure outlining roles, responsibilities, and specific stages for reviewing all information security incidents, from minor events to major breaches. This should include data collection, analysis, and reporting.

2. Implement a robust incident logging and reporting system

Challenge

Inadequate tools or a manual system making it difficult to capture comprehensive incident details and trends.

Solution

Utilise an incident management system (e.g., a ticketing system, dedicated GRC software) to centrally log all incidents, including timestamps, affected assets, impact, remediation steps, and root causes. Ensure clear categorisation and tagging for easier analysis.

3. Conduct thorough root cause analysis (RCA) for all significant incidents

Challenge

Tendency to focus on immediate fixes rather than identifying underlying vulnerabilities or process failures.

Solution

Train staff on RCA methodologies (e.g., 5 Whys, Fishbone diagrams) and mandate their use for all incidents beyond simple anomalies. Encourage a culture of inquiry rather than blame.

4. Document lessons learned from each incident

Challenge

Information gleaned from incidents is not systematically recorded or made accessible for future reference.

Solution

For every incident review, create a “lessons learned” document that summarises the incident, its root cause, the effectiveness of the response, and recommended improvements. Store these centrally in a searchable repository.

5. Communicate lessons learned to relevant stakeholders

Challenge

Siloed knowledge, where valuable insights from incidents are not shared across the organisation, leading to repeated mistakes.

Solution

Establish regular communication channels (e.g., security newsletters, team meetings, dedicated training sessions) to disseminate lessons learned to all relevant employees, including IT, management, and general staff, tailoring the message to their roles.

6. Update risk assessments and treatment plans based on incident findings

Challenge

Incident data is not integrated into the ongoing risk management process, leading to outdated or ineffective controls.

Solution

Periodically review incident trends and specific incidents to identify new or evolving risks. Adjust existing risk assessments, update risk treatment plans, and introduce new controls as necessary to mitigate identified vulnerabilities.

7. Review and improve information security policies and procedures

Challenge

Policies and procedures remain static despite evidence from incidents that they are insufficient or unclear.

Solution

Establish a formal process for reviewing and updating policies and procedures in light of incident findings. This could involve an annual review cycle, or immediate updates triggered by critical incidents.

8. Integrate incident learning into security awareness training

Challenge

Security awareness training is generic and doesn’t reflect the organisation’s specific threat landscape or past incidents.

Solution

Use anonymised examples of real incidents (e.g., phishing attempts, social engineering) in security awareness training to make it more relevant and impactful. Highlight common attack vectors and the importance of employee vigilance.

9. Monitor the effectiveness of implemented improvements

Challenge

Changes are made based on incident reviews, but their actual impact on security posture is not verified.

Solution

Implement metrics and key performance indicators (KPIs) to track the effectiveness of corrective actions. For example, monitor a reduction in specific incident types, faster response times, or improved detection rates.

10. Periodically review the incident management process itself

Challenge

The incident management process becomes stagnant and doesn’t adapt to new threats or organisational changes.

Solution

Conduct regular (e.g., annual) reviews of the entire incident management process, including its effectiveness in identifying, responding to, and learning from incidents. Solicit feedback from incident responders and other stakeholders to identify areas for improvement.

ISO 27001 Annex A 5.27 Audit Checklist

ISO 27001 Learning From Information Security Incidents Audit Checklist

1. Review the existence and effectiveness of a “lessons learned” process

Confirm that the organisation has a formal, documented process for reviewing information security incidents to identify their causes, the effectiveness of the response, and areas for improvement.

Challenges:

The process might exist on paper but not be consistently applied, or staff may not fully understand its importance. There might be a culture of blame rather than learning.

Audit Techniques:

• Document Review: Examine the “lessons learned” policy, procedure, or framework.
• Interviewing: Speak to incident response team members and management about their understanding and application of the process.
• Sample Testing: Select a sample of past incidents and trace whether a lessons learned review was conducted for each.

2. Assess the documentation of post-incident reviews

Verify that formal records of post-incident reviews (PIRs) or post-mortem analyses are maintained for significant incidents, detailing findings, root causes, and recommendations.

Challenges:

Reviews might be informal or incomplete, with insufficient detail to drive meaningful improvements. Key information might be missing.

Audit Techniques:

• Document Review: Examine PIR reports or incident review meeting minutes. Look for evidence of root cause analysis and identified improvement opportunities.
• Observation: If possible, observe a post-incident review meeting in progress.

3. Verify the identification of root causes

Confirm that the organisation actively seeks to identify the underlying reasons for incidents, rather than just addressing the symptoms.

Challenges:

Lack of expertise in root cause analysis, or a tendency to stop at the most obvious cause without digging deeper.

Audit Techniques:

• Interviewing: Question incident responders on their root cause analysis techniques (e.g., “5 Whys,” Fishbone diagrams).
• Case Study Review: Select specific incidents and review the associated documentation to assess the depth and rigour of the root cause analysis performed.

4. Examine the process for tracking and implementing corrective actions

Ensure that identified improvement opportunities and corrective actions from PIRs are formally documented, assigned ownership, have target dates, and are tracked through to completion.

Challenges:

Actions might be identified but not implemented, or there’s no clear ownership, leading to recurring issues.

Audit Techniques:

• Document Review: Review action logs, project plans, or incident management system entries related to corrective actions.
• Follow-up Verification: Select a sample of completed actions and verify their implementation through evidence (e.g., system configurations, updated policies, training records).

5. Assess the integration of lessons learned into the ISMS

Determine if the insights gained from incidents lead to updates in risk assessments, policies, procedures, security controls, or training programmes.

Challenges:

Lessons learned might remain isolated within the incident response team and not be integrated into broader security management.

Audit Techniques:

• Document Review: Trace changes in risk assessments, policies (e.g., access control, patching), or training materials back to specific incident findings.
• Interviewing: Ask the ISMS Manager or risk owner how incident lessons inform their activities.

6. Evaluate communication and awareness of lessons learned

Confirm that relevant lessons learned are effectively communicated to appropriate stakeholders (e.g., incident response team, IT staff, all employees) to prevent recurrence.

Challenges:

Information silos, poor internal communication channels, or a lack of emphasis on sharing knowledge.

Audit Techniques:

• Interviewing: Ask staff if they are aware of past incident learnings and how this knowledge is disseminated.
• Document Review: Look for evidence of awareness campaigns, internal newsletters, or training sessions that incorporate incident lessons.

7. Review the frequency and quality of post-incident review meetings

Ascertain that reviews are conducted regularly (for all significant incidents) and that the meetings are productive, with appropriate attendees.

Challenges:

Reviews might be sporadic, rushed, or lack the right attendees to make effective decisions.

Audit Techniques:

• Document Review: Examine meeting schedules and attendance records for PIRs.
• Interviewing: Discuss with participants the effectiveness and regularity of these meetings.

8. Assess the resourcing and capabilities for post-incident analysis

Confirm that the organisation has sufficient skilled personnel and appropriate tools to conduct thorough incident analysis and derive meaningful lessons.

Challenges:

Insufficient budget, lack of training for staff, or outdated tools preventing in-depth analysis.

Audit Techniques:

• Interviewing: Discuss resource allocation and training programmes for incident responders and analysts.
• Observation: If possible, observe the use of incident analysis tools.
• Document Review: Review training records and budget allocations related to incident response capabilities.

9. Verify the measurement and reporting of incident trends

Ensure that the organisation collects and analyses data on incident types, frequencies, and impacts to identify trends and inform strategic security improvements.

Challenges:

Data might be collected but not analysed, or the analysis isn’t translated into actionable insights.

Audit Techniques:

• Document Review: Examine management review minutes, security dashboards, or incident reports that highlight trends.
• Interviewing: Ask management how incident trend data influences their decision-making.

10. Confirm continuous improvement of the incident management process itself

Determine if the process for managing incidents is itself subject to review and improvement based on lessons learned from both successful and challenging incident responses.

Challenges:

Complacency, or a focus solely on the technical aspects of incidents rather than the efficiency of the response process.

Audit Techniques:

• Document Review: Look for evidence of reviews or updates to the incident response policy and procedures based on past experiences.
• Interviewing: Ask the incident manager or ISMS Manager how they improve the incident management process over time.

Root Cause Analysis Explained

What is root cause analysis?

It is technique that looks to see what the actual cause of an incident was. It is not about identifying the symptoms but what actually caused them and the incident to occur. Consider, I have put on weight. Root cause does not look at the fact your clothes do not fit any more but on why. Through analysis you would likely discover the root cause is you eat too much and don’t exercise enough.

How to do root cause analysis

A good way to is to use the technique of the Five Why’s. By asking the question why five times in a row you can often get to the root of the problem.

For example, if you were looking at the root cause of why you have put on weight.

The incident would be – I have put on weight.

You can then ask the 5 why’s:

• Why? Because I am bigger than before
• Why? Because I eat too much
• Why? Because I am unhappy
• Why? Because I work too hard
• Why? Because I need money.

Root cause of all evil = money.

It can actually be a very effective technique.

What to do with the result

Once we know what the root cause of an information security incident is we can now start to make decision as to what to do. It may be that

• This requires no further action
• This requires corrective action
• This requires continual improvement
• This is a risk and needs to be managed via risk management

Root Cause Conclusion

This guide provides a framework for identifying the root cause, lessons learnt and improvements of an information security incident. The guide should be used in conjunction with your information security incident management plan.

The standard that relates to information security management for further reading if required is ISO/IEC 27035

5 Whys Incident Example

Level	Question	Answer
Problem	Ransomware infected the server.
Why 1	Why did it get in?	Because an admin clicked a phishing link.
Why 2	Why did the link work?	Because the email filter didn’t catch it.
Why 3	Why didn’t the filter catch it?	Because the filter definition was 3 days old.
Why 4	Why was it old?	Because the auto-update server crashed on Friday.
Why 5	Root Cause	No monitoring on the update server.

ISO 27001 Templates

You can save months of effort with these templates that take 25 years of experience and distill it in a pack of prewritten best practice awesomeness. We have included guides on how to respond to incidents and resources to help your implementation.

How to comply

To comply with ISO 27001 Annex A 5.27 Learning From Information Security you are going to implement the ‘how’ to the ‘what’ the control is expecting. You are going to:

1. Manage information security incidents to resolution
2. Perform root cause analysis to identify what caused it
3. Make a decision on what to do next
4. Record information security lessons learnt.

How to pass the ISO 27001 Annex A 5.27 audit

To pass an audit of ISO 27001 Annex A 5.27 Learning From Information Security Incidents you are going to make sure that you have followed the steps above in how to comply. In addition that you:

1. Have a documented process for root cause analysis and lessons learnt.
2. Implement the lessons learnt process
3. Monitor the effectiveness of the lessons learnt process
4. Review and update the lessons learnt process as needed.

What the auditor will check

The audit is going to check a number of areas for compliance with ISO 27001 Annex A 5.27. Lets go through them:

1. That you have documented your root cause and lessons learnt process

The audit will check the documentation, that you have reviewed it and signed and it off and that it represents what you actually do not what you think they want to hear.

2. That you can demonstrate the process working

They are going to ask you for evidence to the lessons learnt process and take one example. For this example you are going to show them and walk them through the process and prove that you followed it and that the process worked.

3. That you can learn your lesson

Documenting your lessons learnt and following this through to continual improvements or incident and corrective actions will be checked. They want to see that not only did you respond but that you learnt from it and did something to improve that reduced or eliminated the possibility of it happening again.

Top 3 ISO 27001 Annex A 5.27 Mistakes People Make and How to Avoid Them

The top 3 Mistakes People Make For ISO 27001 Annex A 5.27 are

1. Not having a documented information security incident management plan

This is the most common mistake made by organisations. A documented information security incident management plan is essential for effective incident response. It should include the following a process for root cause analysis and lessons learnt.

2. Not implementing the information security incident management plan

Even if you have a documented information security incident management plan, it is not enough to simply have the plan. The plan must be implemented in order to be effective. This means assigning responsibility for implementing the plan, providing training on the plan, and testing the plan.

3. Not monitoring the effectiveness of the information security incident management lessons learnt

Once the information security incident management lessons learnt is implemented, it is important to monitor its effectiveness. This means reviewing reports of information lessons learnt, root cause analysis, risk registers, corrective action logs and actual corrective actions implemented as needed.

By avoiding these mistakes, you can ensure that you have an effective information security incident management plan in place.

Applicability of ISO 27001 Annex A 5.27 across different business models.

Business Type	Applicability	Examples of Control Implementation
Small Businesses	Focuses on simple, low-overhead learning to prevent recurring mistakes. The goal is to ensure that even a small team stops to analyze why a simple issue occurred (like a lost laptop or phishing click) and takes one corrective action.	Conducting a 15-minute “Lessons Learned” meeting after a phishing attempt to show staff what the malicious email looked like. Updating the Acceptable Use Policy (AUP) to specifically prohibit the behavior that led to a minor security event. Using a simple “5 Whys” spreadsheet to identify that a lost device wasn’t encrypted because the manual setup checklist was missed.
Tech Startups	Critical for startups with fast-moving codebases and high technical debt. Compliance involves integrating incident learning into the development lifecycle to ensure technical vulnerabilities are permanently remediated.	Mandating a formal Post-Incident Review (PIR) for all cloud outages or security breaches, with findings reported to the CTO. Automating the link between the Incident Log and the Corrective Action Log to ensure root causes (like unpatched dependencies) are tracked to closure. Creating a “Security Retro” session for developers to discuss how a recent bug bypassed CI/CD security scans.
AI Companies	Vital for protecting specialized AI assets and research data. Focus is on learning from sophisticated anomalies in data pipelines or model performance that could indicate a deeper security or integrity flaw.	Analyzing “Adversarial Attacks” on a model to understand how filters were bypassed and implementing new Model Hardening techniques. Conducting a root cause analysis when unauthorized data is discovered in a training set to identify gaps in the data ingest pipeline. Updating Data Anonymization procedures following an incident where special category data was inadvertently exposed during model inference.

Fast Track ISO 27001 Annex A 5.27 Compliance with the ISO 27001 Toolkit

For ISO 27001 Annex A 5.27 (Learning from information security incidents), the requirement is to use knowledge gained from security incidents to strengthen and improve your security controls. This is a preventive control that ensures you don’t just “fix” a problem, but identify the root cause so it never happens again.

Compliance Factor	SaaS Compliance Platforms	High Table ISO 27001 Toolkit	Audit Evidence Example
Intellectual Ownership	Rents access to your post-incident history; if you cancel the subscription, your documented Root Cause Analyses (RCA) and history vanish.	Permanent Assets: Fully editable Word/Excel Incident and Corrective Action Logs that you own and host forever.	A localized “Root Cause Analysis Report” using the 5 Whys technique to identify systemic control failures.
Investigative Utility	Attempts to “automate” learning via dashboards that cannot conduct a nuanced root cause investigation or identify systemic fixes.	Governance-First: Formalizes your existing post-mortems into an auditor-ready framework for continuous improvement.	A completed “Corrective Action Log” proving that an incident led to a specific, documented change in security controls.
Cost Efficiency	Charges an “Improvement Tax” based on the number of corrective actions or projects tracked, creating perpetual overhead.	One-Off Fee: A single payment covers your learning governance whether you have 2 incidents or 200.	Allocating budget to remediating security vulnerabilities rather than paying monthly “dashboard” subscription fees.
Evolutionary Freedom	Mandates rigid reporting formats that may not align with Agile review processes or specialized technical environments.	100% Agnostic: Procedures adapt to any environment—formal steering committees or lean, collaborative team reviews.	The ability to evolve your security strategy and “lessons learned” process without reconfiguring a rigid SaaS module.

Summary: For Annex A 5.27, the auditor wants to see that you have a formal process for root cause analysis and proof that incidents lead to documented improvements (e.g., records of post-incident reviews and updated risk assessments). The High Table ISO 27001 Toolkit provides the governance framework to satisfy this requirement immediately. It is the most direct, cost-effective way to achieve compliance using permanent documentation that you own and control.

ISO 27001 Annex A 5.27 FAQ

Related ISO 27001 Controls

ISO 27001 Annex A 5.24 Information security incident management planning and preparation

ISO 27001 Annex A 5.25 Assessment and decision on information security events 

ISO 27001 Annex A 5.26 Response to information security incidents

ISO 27001 Annex A 5.28 Collection of evidence

ISO 27001 Annex A 5.29 Information Security During Disruption

ISO 27001 Clause 10.2 Nonconformity and Corrective Action

Further Reading

ISO 27001 Incident and Corrective Action Log Template

Business Continuity Incident Action Log Template

ISO 27001 controls and attribute values

Control type	Information security properties	Cybersecurity concepts	Operational capabilities	Security domains
Preventive	Confidentiality	Identify	Information Security Event Management	Defence
	Integrity	Protect
	Availability