= A post-incident review is a process of analyzing and learning from a security incident, such as a data breach, to improve the security posture and resilience of an organization. A post-incident review should include the following elements12:

A clear and accurate description of the incident, including its scope, impact, timeline, root cause, and contributing factors.

A detailed assessment of the effectiveness and efficiency of the incident response process, including the roles and responsibilities, communication channels, coordination mechanisms, escalation procedures, tools and resources, documentation, and reporting.

An evaluation of the adequacy of existing controls, such as policies, standards, procedures, technical measures, awareness, and training, to prevent, detect, and mitigate similar incidents in the future.

A list of actionable recommendations and improvement plans, based on the lessons learned and best practices, to address the identified gaps and weaknesses in the security strategy, governance, risk management, and incident management.

A follow-up and monitoring mechanism to ensure the implementation and verification of the recommendations and improvement plans.

The most important element to include in a post-incident review following a data breach is the evaluation of the adequacy of existing controls, because it directly relates to the security objectives and requirements of the organization, and provides the basis for enhancing the security posture and resilience of the organization. Evaluating the existing controls helps to identify the vulnerabilities and risks that led to the data breach, and to determine the appropriate corrective and preventive actions to reduce the likelihood and impact of similar incidents in the future. Evaluating the existing controls also helps to align the security strategy and governance with the business goals and objectives, and to ensure the compliance with legal, regulatory, and contractual obligations.

The other elements, such as an evaluation of the effectiveness of the information security strategy, documentation of regulatory reporting requirements, and a review of the forensics chain of custody, are also important, but not as important as the evaluation of the existing controls. An evaluation of the effectiveness of the information security strategy is a broader and more strategic activity that may not be directly relevant to the specific incident, and may require more time and resources to conduct. Documentation of regulatory reporting requirements is a necessary and mandatory task, but it does not provide much insight or value for improving the security posture and resilience of the organization. A review of the forensics chain of custody is a technical and procedural activity that ensures the integrity and admissibility of the digital evidence collected during the incident investigation, but it does not address the root cause or the mitigation of the incident. References = 1: CISM Exam Content Outline | CISM Certification | ISACA 2: CISM Review Manual 15th Edition, page 147