Understanding a Security Audit: A Standards-Aligned Perspective

A security audit is a systematic, independent evaluation of an organisation’s information systems, designed to assess resilience against cybersecurity threats and vulnerabilities. Aligned with internationally recognised standards such as ISO/IEC 27001, GDPR, NIS2, and NIST CSF 2.0, a security audit integrates technical, procedural, and organisational assessments to determine the effectiveness of security controls, regulatory compliance, and risk posture.

Our Approach to Security Auditing

1. ISO/IEC 27001-Aligned Security Assessment

Purpose: Establish a structured foundation for security auditing using the ISO/IEC 27001 Information Security Management System (ISMS) framework.

Key Elements:

  • International Standardisation: Align with a globally accepted framework for managing information security risks.
  • Risk-Based Methodology: Identify, assess, and treat risks using a structured and repeatable process.
  • Compliance Support: Meet cross-jurisdictional requirements, including GDPR (data protection), NIS2 (critical infrastructure), and sector-specific controls (NIST CSF).
  • Continuous Improvement: Establish a lifecycle of monitoring, evaluation, and enhancement of controls through the PDCA (Plan-Do-Check-Act) cycle.

2. Penetration Testing and Technical Validation

Purpose: Validate the effectiveness of technical and organisational controls through simulated attack scenarios.

Alignment:

  • ISO/IEC 27001 A.12.6 & A.18.2: Control testing and technical compliance review.
  • NIST CSF Detect & Protect Functions: Use threat modelling and vulnerability management processes.
  • NIS2 Article 21: Conduct regular testing and auditing of cybersecurity risk management measures.

Scope of Testing:

  • Infrastructure and application testing (external and internal).
  • Evaluation of endpoint security, access control, and response mechanisms.
  • Verification of secure configuration baselines and patch management.
  • Documentation and remediation planning based on exploitability and business impact.

3. Architecture & Infrastructure Security Assessment

Purpose: Assess the resilience and compliance of IT architecture and infrastructure.

Key Steps:

  • Scope Definition: Identify critical systems, assets, locations, and communication flows.
  • Review of Security Architecture: Evaluate network segmentation, encryption protocols, access policies, and identity management in line with NIST CSF and ISO 27001 Annex A.
  • Vulnerability and Configuration Review: Analyze system configurations, firewall rules, and physical/logical security controls.
  • Risk Evaluation: Quantify risks using likelihood-impact models and prioritize remediation using NIST 800-30 or ISO 27005 methods.
  • Physical Security Assessment: Assess facility protection, environmental controls, and access restriction in compliance with NIS2 and ISO 27001 A.11.

Deliverables:

  • Risk register with classification (Critical, High, Medium, Low).
  • Mitigation strategy with control selection mapped to ISO 27001 Annex A and NIST CSF Subcategories.
  • Alignment plan for regulatory obligations under GDPR (privacy-by-design), NIS2 (incident reporting and resilience), and sectoral mandates.

4. Documentation for Compliance and Certification

Objective: Build a comprehensive documentation set to demonstrate conformance to ISO 27001 and supporting frameworks (GDPR, NIST CSF, NIS2).

Core Documents:

  • Information Security Policy: High-level governance statement aligned with ISO 27001 Clause 5 and GDPR Article 24.
  • Risk Assessment and Treatment Plan: Developed under ISO 27005; includes threat modeling, risk ownership, and residual risk decisions.
  • Statement of Applicability (SoA): Justifies control selection based on ISO 27001 Annex A, including GDPR Article 32 controls.
  • Security Procedures Manual: Describes implementation of controls, including incident response, cryptography, physical security, and third-party governance.
  • Document Control Policy: Ensures lifecycle management of ISMS documents (creation, review, revision).
  • Incident Response Plan: Compliant with ISO 27035, NIST SP 800-61, and NIS2 incident notification requirements.
  • Internal Audit Program: Covers audit planning, scope, execution, and corrective action tracking under ISO 19011.
  • Management Review Minutes: Demonstrates continual top-management engagement, required by ISO 27001 Clause 9.
  • Training & Awareness Program: Captures employee accountability and awareness in line with GDPR Article 39 and NIST PR.AT function.
  • Third-Party Security Policy: Governs supplier relationships, aligned with ISO 27036 and NIS2 supply chain requirements.
  • Corrective Actions Records: Documents improvements made following audits, incidents, or risk reassessments.

Continuous Improvement and Security Culture

Security audits are not isolated events but a foundational component of ongoing organizational resilience. By incorporating audit findings, penetration test results, and architectural reviews into a continuous improvement cycle, organizations can:

  • Meet and exceed regulatory expectations.
  • Proactively mitigate emerging threats.
  • Maintain alignment with evolving frameworks such as NIST CSF 2.0 and updates to ISO 27001.
  • Cultivate a robust security culture across business units and supply chains.