Incident Management in ISO 27001
Information security incidents are inevitable — no organization can prevent every possible security event. What distinguishes mature organizations from vulnerable ones is how effectively they detect, respond to, and learn from incidents. ISO 27001 recognizes this through a comprehensive set of incident management controls that require organizations to establish plans and procedures for managing incidents, ensure timely reporting of security events, and use incident information to improve their security posture.
The 2022 version of Annex A addresses incident management through controls A.5.24 through A.5.28, covering planning, assessment, response, learning, and evidence collection. Together, these controls require a complete incident management capability that goes well beyond simply having an incident response plan.
Incident Management Planning (A.5.24)
Control A.5.24 requires organizations to plan and prepare for managing information security incidents by defining, establishing, and communicating incident management processes, roles, and responsibilities. Your incident management plan should define what constitutes an information security event versus an incident — events are observable occurrences that may indicate a security issue, while incidents are events that actually compromise or threaten to compromise information security.
Establish a clear classification scheme for categorizing incidents by type and severity. Common categories include malware infections, unauthorized access, data breaches, denial of service, physical security breaches, and social engineering attacks. Severity levels typically range from low impact events that can be handled through normal operations to critical incidents requiring emergency response and executive notification.
Define response procedures for each incident category and severity level, including initial containment actions, investigation procedures, escalation criteria, communication requirements, and recovery steps. Assign roles including incident coordinator, technical investigators, communications lead, and management liaison. Ensure that contact information for all incident response personnel is current and accessible.
Event Reporting (A.6.8 and A.5.25)
Control A.6.8 requires that personnel report observed or suspected information security events through appropriate channels in a timely manner. Create simple, well-communicated reporting procedures that make it easy for anyone in the organization to report a security concern. The reporting mechanism should be accessible through multiple channels — email, phone, and an internal ticketing system all provide options for different situations.
Control A.5.25 requires assessment and decision on information security events. Not every reported event is an incident, and your procedures must include a triage process for evaluating reported events, determining whether they constitute actual incidents, and classifying them appropriately. This assessment should occur promptly to ensure that genuine incidents receive timely response.
Train all personnel to recognize potential security events and understand the reporting procedures. Emphasize that reporting is encouraged and that there are no negative consequences for good-faith reports that turn out to be false alarms. A culture that encourages reporting catches incidents earlier and limits their impact.
Response and Recovery (A.5.26)
Control A.5.26 requires that information security incidents are responded to in accordance with documented procedures. Your response procedures should follow a structured lifecycle: containment to stop the incident from spreading, investigation to understand the scope and root cause, eradication to remove the threat from your environment, recovery to restore affected systems and services, and communication to keep stakeholders informed throughout.
Containment decisions often involve trade-offs between stopping the incident quickly and preserving evidence for investigation. Your procedures should provide guidance for common containment scenarios — isolating an infected workstation, disabling a compromised account, blocking malicious network traffic — while emphasizing the importance of evidence preservation.
Document all actions taken during incident response, including decisions made, by whom, at what time, and with what rationale. This documentation serves multiple purposes: it supports the investigation, provides a basis for post-incident review, satisfies evidence collection requirements, and demonstrates due diligence to auditors and stakeholders.
Learning from Incidents (A.5.27)
Control A.5.27 requires that knowledge gained from information security incidents is used to strengthen and improve security controls. After each significant incident, conduct a post-incident review that examines what happened and why, whether existing controls failed or were inadequate, how effectively the response procedures worked, what improvements should be made to prevent recurrence, and whether similar risks exist elsewhere in the organization.
Document the findings of post-incident reviews and track the implementation of recommended improvements. Feed incident trends and lessons learned into your risk assessment process to ensure that your risk profile reflects actual threat experience. Present incident management metrics and trends to management review meetings to support resource allocation and strategic security decisions.
Evidence Collection (A.5.28)
Control A.5.28 requires organizations to establish and apply procedures for the identification, collection, acquisition, and preservation of evidence related to information security events. Proper evidence handling is essential for supporting incident investigation, meeting legal or regulatory reporting obligations, supporting potential legal proceedings, and demonstrating due diligence to stakeholders.
Your evidence collection procedures should address maintaining a chain of custody that documents who handled the evidence and when, using forensically sound collection methods that preserve evidence integrity, storing evidence securely to prevent tampering or loss, and retaining evidence for the period required by your policies and applicable regulations.
Testing Your Incident Management Capability
While not explicitly required by a single Annex A control, testing your incident management capability is essential for ensuring it works when needed and is an expectation of mature ISMS implementations. Conduct tabletop exercises at least annually to walk through incident scenarios and test your team’s knowledge of procedures and decision-making capabilities.
Easy Compliances provides incident management training, plan templates, and exercise scenarios designed for ISO 27001 compliance. Our resources help you build an incident management capability that satisfies audit requirements while genuinely protecting your organization from the impact of security incidents.