Internal Audit
A systematic, independent evaluation conducted by an organization's own personnel or contracted auditors to assess the effectiveness of its management system, controls, and processes against defined criteria such as ISO 27001 requirements or internal policies.
Internal audits are a mandatory component of ISO 27001 (Clause 9.2) and a best practice for any organization maintaining a compliance program. Unlike external audits conducted by certification bodies, internal audits are self-directed — the organization defines the audit program, selects auditors, and determines the scope and frequency. However, the fundamental requirement is that auditors must be independent of the processes they are auditing (auditors should not audit their own work). Internal audits serve multiple purposes: verifying that the management system conforms to planned arrangements and requirements, identifying nonconformities and improvement opportunities, and providing management with assurance that controls are operating effectively.
The internal audit process typically follows a structured cycle. It begins with audit planning, where the audit program defines which areas will be audited, when, and by whom — considering the importance of processes and results of previous audits. Audit execution involves reviewing documentation, interviewing personnel, observing processes, and examining evidence. Findings are documented in an audit report that categorizes issues as nonconformities (failures to meet requirements) or opportunities for improvement. Follow-up ensures that corrective actions are implemented and effective. SOC 2 engagements often evaluate whether organizations have internal monitoring and audit mechanisms in place. NIS2 encourages regular testing and auditing of cybersecurity measures.
For organizations pursuing or maintaining ISO 27001 certification, a robust internal audit program is essential. The audit program should cover all clauses of the standard and all applicable Annex A controls over a defined cycle (typically 12 months). Auditors should be trained in audit techniques — ISO 19011 provides comprehensive guidance on auditing management systems. Organizations with limited internal resources can use external consultants to perform internal audits, provided the auditors maintain independence from the processes being audited. The results of internal audits feed directly into the management review process and provide the basis for continuous improvement of the information security management system.
Related terms
Audit Evidence
The documented records, observations, test results, and other verifiable information collected during an audit to determine whether the organization's controls and processes conform to the specified requirements and are operating effectively.
Corrective Action
A documented action taken to eliminate the root cause of a detected nonconformity or other undesirable situation, preventing its recurrence. Corrective actions go beyond simply fixing the immediate problem to address the underlying systemic issue.
External Audit
An independent assessment conducted by a third-party auditor or certification body to evaluate an organization's compliance with a specific standard or framework, such as ISO 27001 certification audits or SOC 2 examinations.
Management Review
A formal, periodic evaluation by top management of the organization's information security management system to ensure its continuing suitability, adequacy, effectiveness, and alignment with strategic direction. Required by ISO 27001 Clause 9.3.
Nonconformity
A failure to fulfill a requirement of a standard, policy, procedure, regulation, or contractual obligation. In the context of management systems like ISO 27001, nonconformities are categorized as major (systemic failure or significant gap) or minor (isolated or partial failure).
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