Final answer:
The Chief Security Officer would most likely use a tabletop exercise to validate the business's involvement in the incident response plan. They may also consider an external security assessment and a red-team engagement to further ensure the plan's validity and thoroughness.
Step-by-step explanation:
The Chief Security Officer (CSO) of an organization will most likely use a tabletop exercise to validate the business's involvement in the incident response plan. A tabletop exercise is a simulation of an incident response scenario that allows key stakeholders to test and validate their roles, responsibilities, and procedures in responding to an incident. It helps identify any gaps or weaknesses in the plan and allows for improvements to be made.
Additionally, the CSO may also use an external security assessment to ensure the validity and thoroughness of the incident response plan. An external security assessment involves hiring a third-party organization to assess the organization's security controls, identify vulnerabilities, and provide recommendations for improvement.
Furthermore, the CSO might consider a red-team engagement to test the effectiveness of the incident response plan. A red team is a group of skilled individuals who simulate real-world attackers and attempt to exploit vulnerabilities in the organization's systems and processes. The results of a red-team engagement can help identify areas for improvement in the incident response plan.