The internal audit activity needs to review the information security function but does not have...

When the internal audit activity lacks the necessary IT expertise to review the information security function, the chief audit executive (CAE) should contract an external service provider with the required experience. This ensures that the audit is conducted effectively and in accordance with the Standards, which require internal auditors to have or acquire the necessary skills to perform their work.

IIA References:

IIA Standard 1210: Proficiency requires internal auditors to possess the knowledge, skills, and other competencies needed to perform their responsibilities. When the necessary expertise is not available within the internal audit activity, the CAE must obtain competent advice and assistance by either contracting external experts or outsourcing the audit.

The Practice Guide on Engaging External Service Providers suggests that when specialized skills are required, engaging an external service provider is a practical solution to ensure the audit's quality and effectiveness.