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.
References:
* 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

According to ISO/IEC 27001:2022, the corrective action process consists of the following steps12:
* Reacting to the nonconformity and, as applicable, taking action to control and correct it and deal with the consequences
* Evaluating the need for action to eliminate the root cause(s) of the nonconformity, in order that it does not recur or occur elsewhere
* Implementing the action needed
* Reviewing the effectiveness of the corrective action taken
* Making changes to the information security management system, if necessary In scenario 9, the ISMS project manager did not complete the last step of reviewing the effectiveness of the corrective action taken. This step is important to verify that the corrective action has achieved the intended results and that no adverse effects have been introduced. The review can be done by using various methods, such as audits,tests, inspections, or performance indicators3. Therefore, the ISMS project manager did not complete the corrective action process appropriately.
References:
1: ISO/IEC 27001:2022, clause 10.2 2: Procedure for Corrective Action [ISO 27001 templates] 3: ISO 27001 Clause 10.2 Nonconformity and corrective action

A demilitarized zone (DMZ) is a network segment that separates the internal network from the external network, such as the Internet. It is used to host public services that need to be accessible from outside the organization, such as web servers, email servers, or DNS servers. A DMZ provides a layer of protection for the internal network by limiting the exposure of the public services and preventing unauthorized access from the external network. A DMZ is an example of a preventive control, which is a type of control that aims to prevent or deter the occurrence of an information security incident. Preventive controls reduce the likelihood of a threat exploiting a vulnerability and causing harm to the organization's information assets. Other examples of preventive controls are encryption, authentication, firewalls, antivirus software, and security awareness training.
References:
* ISO/IEC 27001 : 2022 Lead Implementer Study Guide, Section 8.2.3.2.1, page 162
* ISO/IEC 27001 : 2022 Lead Implementer Info Kit, page 13
* ISO/IEC 27002 : 2022, Section 13.1.3, page 66