Supplier risk does not stay static. Over my 30 years in governance, risk, and compliance, I have seen far too many organisations conduct a rigorous security assessment during supplier onboarding, sign a tight contract, and then completely ignore the vendor for three years. In the meantime, the supplier migrates its infrastructure to a new cloud region, introduces unvetted sub-processors, updates its software stack, or downgrades its incident response SLA. Unmanaged supplier drift is one of the most common vectors for major third-party security failures and data breaches. Annex A 5.22 ensures you maintain active visibility, conduct periodic performance reviews, and manage vendor operational changes systematically throughout the entire lifecycle of the relationship.
ISO 27001:2022 includes Annex A 5.22 to ensure your organisation actively monitors, reviews, and manages changes to supplier service delivery to maintain agreed information security standards. This control updates former 2013 requirements (15.2.1 and 15.2.2) and shifts the focus away from “one-and-done” onboarding checks toward ongoing performance tracking, service change governance, independent re-certification verification, and risk-proportionate vendor oversight.
Quick Summary: What ISO 27001 Annex A 5.23 Requires
At a practical level, Annex A 5.22 is about preventing security erosion across your external supply chain over time. It does not demand heavy-handed, weekly on-site audits for every minor software vendor; it expects a risk-tiered, structured approach focused on critical vendors whose disruption or failure would directly impact your business. Here is what you need to do in plain English:
- Tier Suppliers by Risk & Criticality: Categorize third-party suppliers (Critical, High, Medium, Low) based on their access to sensitive data, systems, or core operational processes.
- Monitor Ongoing Supplier Performance: Track vendor SLA delivery, uptime metrics, incident response times, and security event reports on a regular schedule.
- Conduct Periodic Security Reviews: Re-verify supplier security posture annually for critical vendors by reviewing updated SOC 2 Type II reports, ISO 27001 certificates, or audit questionnaires.
- Govern Supplier Service Changes: Establish formal change review pathways to evaluate vendor updates, infrastructure migrations, or platform changes before they impact your operations (Annex A 8.32).
- Track Subcontracting & Sub-Processor Changes: Require critical suppliers to notify you before introducing major new subcontractors or shifting data processing locations (Annex A 5.34).
- Maintain Auditable Vendor Oversight Logs: Document review findings, identified vendor risks, and corrective action plans centrally inside your ISMS vendor register.
Why “One-and-Done” Supplier Onboarding Is a Critical Hazard
When an organisation assumes that initial vendor onboarding security checks remain valid forever, invisible security risks accumulate across the supply chain. Suppliers evolve, acquire other companies, re-architect their tech stacks, and change security controls behind the scenes.
Ignoring ongoing supplier monitoring and change management controls exposes your business to severe hazards:
- Unnoticed Supplier Security Degradation: A critical SaaS vendor letting its ISO 27001 certification lapse or disabling key encryption controls without your knowledge.
- Uncontrolled Sub-Processor Sprawl: Vendors transferring your sensitive customer PII to unvetted fourth-party subcontractors, violating privacy laws (Annex A 5.34) and client contracts (Annex A 5.31).
- Sudden Outages via Unannounced Upgrades: A vendor executing a major cloud infrastructure migration or software release that breaks API integrations or disrupts business continuity (Annex A 5.30).
- Failed External Audits: Facing severe non-conformities during ISO 27001 audits because vendor risk assessments are outdated and lack evidence of ongoing review.
My 8 Step Plan to Implement Annex A 5.22 Fast
You do not need a massive vendor risk team to satisfy an ISO 27001 auditor. Here is my pragmatic, 8-step plan to establish an audit-ready supplier monitoring and change management framework.
1. Establish a Tiered Supplier Risk Matrix
You cannot monitor every vendor with equal intensity. Segment your supply chain based on risk (Annex A 8.9):
- Tier 1 (Critical / High Risk): Suppliers processing sensitive customer PII, hosting core cloud infrastructure (IaaS/PaaS), or maintaining privileged network access. Action: Annual deep-dive security review, SOC 2/ISO verification, continuous SLA tracking.
- Tier 2 (Medium Risk): Business-essential SaaS applications handling non-sensitive internal operational data. Action: Bi-annual lightweight review, automated vulnerability scanning, certificate verification.
- Tier 3 (Low Risk): Commodity suppliers, office utility providers, or low-impact software without access to corporate data. Action: Basic initial review, passive event tracking.
2. Define Key Performance & Security Metrics (SLAs/KPIs)
Establish measurable metrics to track vendor operational health continuously:
- Track system availability, service uptime SLAs, and maintenance window compliance.
- Monitor security incident response times, vulnerability patch resolution SLAs, and customer notification speed following security events (Annex A 5.26).
- Review automated security rating platform feeds (e.g., BitSight, SecurityScorecard) for continuous risk visibility across Tier 1 vendors.
3. Automate Annual Independent Assurance Collections
Relying on self-reported vendor questionnaires is insufficient. Require independent, third-party verification for Tier 1 suppliers:
- Automate calendar reminders to collect updated SOC 2 Type II reports, ISO/IEC 27001 certificates, or PCI-DSS Attestations of Compliance (AoC) annually.
- Review SOC 2 “Complementary User Entity Controls” (CUECs) carefully to ensure your internal teams are executing the specific security tasks required by the cloud vendor.
- Validate that the scope of the vendor’s ISO 27001 certificate covers the specific service or datacenter region you actually use.
4. Establish a Formal Supplier Change Request Workflow
Require critical suppliers to inform you prior to executing material operational or architectural changes (Annex A 8.32):
- Incorporate mandatory change notification clauses (e.g., 30-day advance notice for major infrastructure, hosting, or API changes) into vendor contracts (Annex A 5.31).
- Review proposed vendor changes through your internal Change Advisory Board (CAB) to evaluate potential impacts on confidentiality, integrity, or availability.
- Test updated vendor APIs, software versions, or integration links in a non-production staging environment before approving production rollouts.
5. Monitor Fourth-Party Subcontractor & Location Changes
Your supply chain risk extends to the sub-processors used by your direct vendors:
- Require Tier 1 vendors to maintain an up-to-date, public or accessible list of sub-processors.
- Mandate explicit notification and opt-out rights before a vendor transfers processing of your customer data to a new sub-processor or overseas jurisdiction (Annex A 5.34).
- Re-evaluate cross-border data transfer legal mechanisms (e.g., Standard Contractual Clauses) if a vendor shifts storage locations.
6. Conduct Joint Incident Response Reviews
Test and review how vendors perform when operational disruptions or security events occur:
- Track and log all vendor-related security incidents, outage durations, and communication quality inside your Central Supplier Register.
- Conduct post-incident reviews (Annex A 5.27) with vendor account leads following major service disruptions to review root cause analysis (RCA) reports.
- Incorporate key vendor emergency contact channels into your master Business Continuity Plans (Annex A 5.30).
7. Document Performance Review Findings & Corrective Action Plans
Assurance activity must produce auditable, tracked outcomes:
- Document all vendor review findings, identified security gaps, and performance deficiencies inside a standardized Vendor Review Summary.
- Issue formal Corrective Action Requests (CARs) to vendors with explicit remediation deadlines when security weaknesses or SLA breaches are spotted.
- Track vendor remediation progress monthly and escalate unaddressed security risks to executive management.
8. Link Ongoing Oversight to Contract Renewals and Offboarding
Ensure that supplier security performance directly informs business procurement decisions:
- Require Procurement to review the vendor’s historical security performance and current audit status prior to authorizing contract renewals.
- Maintain clear exit and offboarding playbooks (Annex A 8.10) to retrieve corporate data, revoke system credentials (Annex A 8.3), and crypto-shred archives if a supplier relationship is terminated.
- Present annual supply chain security summaries to the ISMS Steering Committee during formal Management Reviews.
Common Implementation Pitfalls and How to Fix Them
When preparing clients for ISO 27001 audits, I frequently spot the same supplier oversight mistakes. Here are the main traps and how to solve them:
- Problem: Treating All Vendors the Same, Sending 100-Question Questionnaires to Low-Risk Local Suppliers
Ninja Solution: Implement a 3-tier vendor risk matrix; focus deep annual reviews strictly on Tier 1 critical suppliers. - Problem: Accepting Vendor ISO 27001 Certificates Without Verifying Scope or Expiration Dates
Ninja Solution: Inspect certificate validity dates and verify that the certified scope explicitly includes the specific product, service, and location you utilize. - Problem: Vendors Changing Hosting Locations or Sub-Processors Without Internal IT Knowing
Ninja Solution: Mandate contractual notification clauses for sub-processor changes and review vendor sub-processor lists during annual reviews. - Problem: Reviewing Vendors Once at Contract Signing and Keeping Zero Auditable Records Thereafter
Ninja Solution: Automate annual review tickets in your ISMS platform to collect updated SOC 2 reports and document review summaries centrally.
The ISO 27001 Ninja Bottom Line
ISO 27001 Annex A 5.22 is about preventing security erosion across your extended supply chain over time. Initial vendor onboarding checks only capture a single snapshot in time; active monitoring, periodic reviews, and service change governance ensure your third-party risks remain fully controlled as vendor technologies and business models evolve.
By establishing a tiered vendor risk matrix, tracking security KPIs, automating annual SOC 2/ISO certificate collection, governing vendor service changes, monitoring fourth-party sub-processors, executing joint incident reviews, tracking vendor corrective actions, and linking security performance to contract renewals, you eliminate supply chain blind spots, maintain continuous compliance, and satisfy your ISO 27001 auditor with complete confidence.