According to the ISO/IEC 27001:2022 standard, an internal audit is an audit conducted by the organization itself to evaluate the conformity and effectiveness of its information security management system (ISMS). The standard requires that the internal audit should be performed by auditors who are objective and impartial, meaning that they should not have any personal or professional interest or bias that could influence their judgment or compromise their integrity. The standard also allows the organization to outsource the internal audit function to a third party, as long as the criteria of objectivity and impartiality are met.

Outsourcing the internal audit function to a third party can be a better option for small organizations that may not have enough resources, skills, or experience to perform an internal audit by themselves. By hiring an external auditor, the organization can benefit from the following advantages:

The external auditor can provide a fresh and independent perspective on the organization’s ISMS, identifying strengths, weaknesses, opportunities, and threats that may not be apparent to the internal staff.

The external auditor can bring in specialized knowledge, expertise, and best practices from other organizations and industries, helping the organization to improve its ISMS and achieve its objectives.

The external auditor can reduce the risk of conflict of interest, bias, or influence that may arise when the internal staff audit their own work or the work of their colleagues.

The external auditor can save the organization time and money by conducting the internal audit more efficiently and effectively, avoiding duplication of work or unnecessary delays.

Therefore, outsourcing the internal audit function to a third party is acceptable and often preferable for small organizations that are implementing an ISMS based on ISO/IEC 27001.

ISO/IEC 27001:2022, Information technology — Security techniques — Information security management systems — Requirements, Clause 9.2, Internal audit

ISO/IEC 27007:2023, Information technology — Security techniques — Guidelines for information security management systems auditing

PECB, ISO/IEC 27001 Lead Implementer Course, Module 12, Internal audit

A Complete Guide to an ISO 27001 Internal Audit - Sprinto