Implementing ISO 27001 Annex A 5.26 is the essential process of establishing a robust technical response to security incidents. The primary implementation requirement focuses on active containment and forensic evidence preservation, delivering the business benefit of minimized operational downtime and full compliance with international data protection standards.
ISO 27001 Annex A Response to Information Security Incidents Implementation Checklist
Use this implementation checklist to achieve compliance with ISO 27001 Annex A 5.26. Successful certification requires evidence of active, manual intervention during security events rather than passive reliance on automated software notifications.
1. Formal Activation of the Incident Response Team (IRT)
Control Requirement: A designated team must be formally mobilised following the assessment of a security event as an incident.
Required Implementation Step: Open your Incident Management Procedure and trigger the call-out list via telephone or secure out-of-band messaging. Do not rely on a GRC dashboard; you must physically or digitally verify that each member has acknowledged their specific role in the response.
Minimum Requirement: Provide a dated call-log or timestamped message thread showing the IRT Lead officially declaring the incident and assigning roles.
2. Immediate Containment and Isolation
Control Requirement: Actions must be taken to limit the spread and impact of the incident.
Required Implementation Step: Execute physical or logical isolation of the affected assets. This involves logging into the firewall or hypervisor to shut down ports or isolate VLANs, ensuring the threat cannot traverse the network while you investigate.
Minimum Requirement: Evidence of a specific configuration change (e.g., a firewall rule update) timestamped within the incident window.
3. Preservation of Volatile Evidence
Control Requirement: Evidence must be collected and protected before it is lost or tampered with during the response.
Required Implementation Step: Create a bit-for-bit image of affected memory (RAM) or disk partitions before rebooting or patching. Document the chain of custody manually, including the name of the person who performed the dump and the hash of the resulting file.
Minimum Requirement: A signed evidence log containing the SHA-256 hash of the forensic image captured during the triage.
4. Manual Root Cause Triage
Control Requirement: The incident must be analysed to identify the specific vulnerability or threat actor activity.
Required Implementation Step: Assign a technical lead to review raw system logs and packet captures. Avoid “one-click” automated summaries; you must document the specific lines of code or log entries that prove how the perimeter was breached.
Minimum Requirement: A technical report detailing the specific CVE or misconfiguration exploited, verified by a human analyst.
5. Strategic Eradication of the Threat
Control Requirement: The cause of the incident must be eliminated from the environment.
Required Implementation Step: Manually delete malicious files, disable compromised accounts, and apply patches to the vulnerable service. This must be done across the entire estate, not just the single server where the incident was detected.
Minimum Requirement: A list of actions taken to “clean” the environment, such as “Reset 50 user passwords” or “Patched Apache version 2.4.x”.
6. Secure Restoration from Trusted Backups
Control Requirement: Systems must be restored to a secure state using verified data.
Required Implementation Step: Restore data from a known-good backup that predates the incident. You must perform an integrity check on the restored data to ensure the threat has not been re-introduced through the backup itself.
Minimum Requirement: A verification log showing that the restored system was scanned for the original indicators of compromise (IoC) before going live.
7. Execution of Internal Communications
Control Requirement: Relevant internal stakeholders must be kept informed on a need-to-know basis.
Required Implementation Step: Send manual updates to the Board and relevant Department Heads. Avoid mass emails; use controlled communication channels to prevent “leakage” of the incident details to unauthorised staff or the public.
Minimum Requirement: Minutes from an IRT briefing session or a sent-item copy of a restricted internal update email.
8. Regulatory and External Notification
Control Requirement: External parties and regulators must be notified if legal or contractual obligations are triggered.
Required Implementation Step: Open your legal register and determine if the 72-hour GDPR (or relevant UK DPA) window applies. If so, manually draft the notification to the ICO or relevant regulator, ensuring it includes only confirmed facts.
Minimum Requirement: A copy of the notification sent to the regulator or a legal memo explaining why no notification was required.
9. Post-Response Integrity Verification
Control Requirement: The restored environment must be monitored for a defined period to ensure the threat is fully resolved.
Required Implementation Step: Set up specific monitoring alerts for the IoCs associated with the incident. A human analyst must review these alerts daily for at least 7 days post-remediation to confirm no re-infection has occurred.
Minimum Requirement: 7 days of monitoring logs showing “no further incidents” following the closure of the initial ticket.
10. Formal Incident Closure and Handover
Control Requirement: The incident must be officially closed once all response activities are complete.
Required Implementation Step: The IRT Lead must sign off on the incident report. This is a manual approval that confirms all evidence has been stored and all remediation steps have been verified as effective.
Minimum Requirement: A final incident report with a wet-ink or verified digital signature from the Senior Information Risk Owner (SIRO).
ISO 27001 Annex A 5.26 SaaS / GRC Platform Implementation Failure Checklist
| Control Requirement | The ‘Checkbox Compliance’ Trap | The Reality Check |
|---|---|---|
| Containment | The GRC tool shows a “Containment Policy” PDF uploaded to a folder. | Auditors want to see the actual SSH log of a server being isolated during a crisis. |
| Evidence Collection | Clicking a “Collect Evidence” button that just records a timestamp in the tool. | Real evidence is a forensically sound disk image with a verified SHA-256 hash. |
| Root Cause Analysis | Selecting “Human Error” from a pre-defined dropdown menu in a dashboard. | True compliance requires a technical deep-dive into log files and memory dumps. |
| IRT Activation | Sending an automated notification email that goes to a junk folder. | Compliance is proven through out-of-band communication logs (e.g., Signal or Phone). |
| Restoration Integrity | Marking a task as “Done” in a workflow management system. | Auditors require proof of a clean scan performed on restored data before it was re-exposed. |
| Regulatory Reporting | A generic countdown timer for “GDPR Notification” inside the app. | Success is the manual drafting of a specific legal notice based on confirmed data loss. |
| Communication Control | Automated status pages that notify the entire company by default. | Control 5.26 requires “need-to-know” restrictions, which automated blasts often violate. |
| Incident Closure | An automated bot closing the ticket because no one replied for 48 hours. | A human lead must manually verify that every remediation step was physically completed. |
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