ISO 27001 Annex A 5.21: Managing information security in the ICT supply chain

What auditors look for

Auditors check that 5.21 is either justified as not applicable in your Statement of Applicability or implemented and working. Typical evidence includes:

• Sub-processor and fourth-party lists
• Software dependency inventory or SBOM
• Supplier answers on their own supplier controls

How to implement 5.21 in practice

1. Ask critical suppliers how they assess their suppliers
2. Track open source dependencies
3. Monitor advisories for key components
4. Name an owner for 5.21, decide how often it runs and file evidence each time, so the control is audit-ready all year.

Recording 5.21 in the Statement of Applicability

List 5.21 with whether it applies, the reason (usually the risks it treats or a legal or contractual requirement), its implementation status and where the evidence lives. If you exclude it, explain why none of your risks or obligations require it.

Free resources

• Vendor security questionnaire template
• ISO 27001 and GDPR readiness assessment
• 10 steps to implement ISO 27001
• Remote ISO 27001 consultant

More organizational controls

• 5.17 Authentication information
• 5.18 Access rights
• 5.19 Information security in supplier relationships
• 5.20 Addressing information security within supplier agreements
• 5.22 Monitoring, review and change management of supplier services
• 5.23 Information security for use of cloud services
• 5.24 Information security incident management planning and preparation
• 5.25 Assessment and decision on information security events