Independent review of information security is a mandatory governance process under ISO 27001 Control 5.35 to ensure objective system oversight. The appointment of impartial reviewers is the primary implementation requirement, delivering the business benefit of verified compliance and the identification of technical vulnerabilities before certification audits.
What is Independent review of information security?
ISO 27001 Independent review of information security focuses on making sure your security measures are looked at by someone who isn’t involved in their day-to-day use. Think of it like getting a second opinion from a doctor.
Examples
- A small business that has its IT department handle security might hire an outside expert to check their systems once a year. This check would ensure their data is protected.
- A big company might have a dedicated team for internal audits. This team doesn’t manage the company’s daily IT, so they can give an honest, unbiased review of how well the security is working.
- A security professional may be asked to review the logs of a company’s firewall to check if the security measures are effective.
Context
The main point of this control is to have a neutral person or team check your information security. This review helps find weaknesses you might have missed. It ensures that the security rules you’ve set up are actually working well and that they follow your company’s policy. The goal is to make sure your information is safe from harm, like being lost or stolen.
How to implement Independent review of information security
1. Establish the Independent Review Programme
Provision a formal audit schedule that defines the frequency and depth of independent assessments: This ensures that all 93 Annex A controls and mandatory clauses are reviewed within a three-year cycle. Key requirements include:
- Documenting the audit intervals based on risk assessment results.
- Securing budget for external specialist auditors or internal cross-departmental teams.
- Aligning the programme with the organisation’s management review cycle.
2. Appoint Independent and Competent Reviewers
Formalise the selection of individuals who are impartial and independent of the ISMS implementation: This maintains 100% objectivity and prevents the risk of “self-auditing” which is a common audit fail-point. Selection criteria involve:
- Verifying Lead Auditor certifications or equivalent technical expertise.
- Ensuring reviewers have no operational responsibility for the controls being tested.
- Documenting the independence of the audit team within the ISMS records.
3. Provision the Rules of Engagement (ROE)
Formalise an ROE document that defines the technical boundaries, communication protocols, and scope of the review: This prevents scope creep and ensure the technical testing does not disrupt business operations. Technical requirements include:
- Mapping the review scope to the current Asset Register.
- Defining the start and end dates for the fieldwork phase.
- Establishing the escalation path for discovered critical vulnerabilities.
4. Grant Technical Access via IAM Roles
Provision read-only Identity and Access Management (IAM) roles for the reviewers to verify technical configurations: This allows for the inspection of security groups, firewall rules, and MFA logs without compromising system integrity. Necessary actions include:
- Enforcing Multi-Factor Authentication for reviewer accounts.
- Restricting access to “Audit Only” permissions across cloud environments.
- Revoke all access immediately upon completion of the fieldwork.
5. Audit Technical Control Implementation
Execute technical verification of Annex A controls to ensure they meet the Statement of Applicability (SoA) requirements: This provides objective evidence that technical safeguards are active rather than just documented. Implementation verification involves:
- Inspecting the configuration of Endpoint Detection and Response (EDR) tools.
- Verifying the status of encryption for data at rest and in transit.
- Reviewing the results of recent vulnerability scans and penetration tests.
6. Audit Documentation and Policy Alignment
Audit the internal policy library to ensure 100% alignment with the actual technical workflows: This identifies discrepancies where “say” does not match “do,” which often leads to major non-conformities. Review tasks include:
- Checking version control and management approval on all security policies.
- Verifying that Standard Operating Procedures (SOPs) are citable and followed.
- Confirming that NDAs and contractor agreements include the required security clauses.
7. Formalise Findings and Non-conformities
Formalise all audit findings into a structured report that categorises issues as major non-conformities, minor non-conformities, or opportunities for improvement: This provides management with a clear technical gap analysis. Requirements include:
- Linking every finding to a specific ISO 27001 clause or control.
- Providing citable evidence for every non-conformity identified.
- Securing sign-off on the findings from relevant process owners.
8. Trigger the Management Review Process
Formalise the presentation of the independent review results to senior leadership during a Clause 9.3 Management Review: This ensures that the technical findings are translated into business risk decisions. Review inputs involve:
- Reviewing the status of the ISMS performance and effectiveness.
- Allocating resources for necessary technical remediations.
- Documenting the management’s response to the independent findings.
9. Provision Corrective Action Plans
Formalise a remediation roadmap to address the identified gaps and prevent the recurrence of issues: This closes the “Check-Act” loop of the PDCA cycle. Implementation steps are:
- Assigning technical owners and deadlines for every corrective action.
- Conducting a Root Cause Analysis (RCA) for all major findings.
- Updating the Risk Treatment Plan to reflect the new technical state.
10. Audit Remediation Evidence and Close
Audit the evidence provided by technical teams to verify that corrective actions have been implemented effectively: This ensures the organisation is audit-ready for the final UKAS assessment. Necessary actions include:
- Re-testing technical controls that previously failed inspection.
- Updating the Internal Audit Log to show the “Closed” status.
- Archiving the review records as evidence for the certification body.
Independent review of information security FAQ
What is an independent review of information security?
An independent review of information security is a mandatory assessment of an organisation’s security management system conducted by individuals not involved in the system’s implementation. Required by ISO 27001:2022 Control 5.35, it ensures 100% objectivity in evaluating security controls and identifying gaps before external UKAS certification assessments.
Who is qualified to conduct an independent security review?
The review must be conducted by competent individuals who are impartial and independent of the specific area or process being audited. This can be achieved using internal staff from separate departments or external Lead Auditors, provided they maintain 100% independence from the daily management of the controls.
How often should an independent review be performed?
Organisations must perform independent reviews at planned intervals or whenever significant changes occur to the security environment. Most compliant firms conduct these at least once every 12 months to align with the 3-year ISO 27001 certification cycle, ensuring all 93 controls are verified for operational effectiveness.
What are the business benefits of an independent security review?
An independent review reduces the risk of major non-conformities during formal audits by approximately 40% and provides management with citable evidence of security maturity. Key advantages include:
- Objective Validation: Removing internal bias from security performance reporting.
- Risk Mitigation: Early identification of technical vulnerabilities before they lead to data breaches.
- Regulatory Compliance: Meeting legal requirements for independent oversight in highly regulated sectors.
- Stakeholder Trust: Providing 100% assurance to clients that security claims are externally verified.
Relevant ISO 27001 Controls
The following controls from the ISO/IEC 27001:2022 standard are related to independent review of information security:
- ISO 27001:2022 Annex A 5.35 Independent Review Of Information Security: This is the core control being discussed.
- ISO 27001:2022 Annex A 5.1: Policies for Information Security: The independent review checks if the security measures align with the company’s security policies.
| Related ISO 27001 Control / Clause | Relationship Description |
|---|---|
| ISO 27001 Annex A 5.35: Independent Review of Information Security | Core Requirement: The primary control that mandates the organization’s approach to managing information security and its implementation be reviewed independently at planned intervals or when significant changes occur. |
| ISO 27001 Annex A 5.1: Policies for Information Security | Governance Alignment: The independent review specifically evaluates whether security measures and operational practices are in alignment with the organization’s established security policies. |
| ISO 27001 Clause 9.2: Internal Audit | Methodological Link: Internal audits are the most common formal mechanism used to fulfill the requirement for an independent and objective review of the ISMS. |
| ISO 27001 Clause 9.3: Management Review | Accountability: The results of independent reviews must be reported to top management during the management review process to ensure oversight and resource allocation. |
| Glossary: Internal Audit | Practical Execution: Describes the planned process of evaluating the ISMS by competent personnel who are independent of the day-to-day activities being audited. |
| Glossary: Nonconformity | Review Findings: Independent reviews are designed to identify nonconformities—instances where security practices fail to meet the requirements of the standard or internal policies. |
| Glossary: Continual Improvement | Strategic Outcome: By identifying weaknesses and missing security steps, independent reviews provide the necessary insights to drive the “Act” phase of the PDCA cycle for the ISMS. |
| ISO 27001 Glossary of Terms (Main Index) | Parent Directory: The central index where Independent Review is categorized as a critical governance and assurance term. |
Further Reading
ISO 27001 Independent Review Of Information Security: Your Complete FAQ Guide
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