When vendors present ISO 27001 certificates or SOC 2 reports, executives often treat them as proof of adequate security. While these certifications are valuable signals, they are not guarantees. Understanding what each certification actually covers—and what it does not—is essential for making informed risk decisions. A certificate on the wall does not automatically mean your data is safe.
ISO 27001 vs SOC 2: What They Tell You
These two certifications are the most commonly presented by vendors, but they serve different purposes and have different scopes:
- ISO 27001 — an international standard for information security management systems (ISMS). It certifies that the vendor has established, implemented, maintained, and continually improved a systematic approach to managing information security. The certificate covers the management system itself, not specific technical controls.
- SOC 2 Type I — a point-in-time attestation that security controls are designed appropriately as of a specific date. It confirms the controls exist but does not test whether they operate effectively over time.
- SOC 2 Type II — covers a period (typically 6-12 months) and tests whether controls operated effectively throughout that period. This is significantly more valuable than Type I because it provides evidence of sustained implementation.
- Scope limitations — both certifications cover only what is defined in the scope. A vendor may certify one product or data centre while leaving others unaudited.
Diagram
ISO 27001 vs SOC 2 Comparison Matrix
A side-by-side comparison showing scope, audit type, period covered, trust services criteria, and key limitations of ISO 27001, SOC 2 Type I, and SOC 2 Type II
Reading Between the Lines
Always request the full SOC 2 report, not just the opinion letter. The report includes a description of the system, the trust services criteria evaluated (security, availability, processing integrity, confidentiality, privacy), any exceptions or qualifications noted by the auditor, and management’s responses. Exceptions are not automatic deal-breakers but must be evaluated in the context of your specific data and risk tolerance.
For ISO 27001, review the Statement of Applicability (SoA), which lists all 93 Annex A controls and indicates which are implemented and which are excluded with justification. Exclusions may cover areas critical to your use case.
Action Steps
- Always verify that the certification scope covers the specific services and data your organisation uses
- Request the full SOC 2 Type II report, not just the summary, and review auditor exceptions carefully
- For ISO 27001, request the Statement of Applicability to check for excluded controls relevant to your data
- Treat certifications as one input into your assessment, not as a substitute for your own due diligence
Quick Knowledge Check
- What is the key difference between SOC 2 Type I and Type II?
Type I evaluates control design at a single point in time, while Type II tests whether controls operated effectively over a sustained period (typically 6-12 months). - Why should you review the ISO 27001 Statement of Applicability?
Because it reveals which of the 93 Annex A controls the vendor excluded from scope, and those exclusions may cover areas critical to protecting your data.