They should anchor each assessment to actual access, data exposure, and privilege scope. Questionnaires and certifications are useful inputs, but they do not show whether a vendor can reach sensitive systems or retain access after the business need changes. The assessment should end with a control decision, not a score alone.
Why This Matters for Security Teams
Third-party vendor assessment becomes wasteful when it measures documentation quality instead of real access. A vendor can have polished answers and still hold OAuth grants, API keys, or service accounts that reach sensitive systems long after the business case changed. That gap is why NHI security has become a supply-chain issue, not just an IAM issue. The State of Non-Human Identity Security shows that 85% of organisations lack full visibility into third-party vendors connected via OAuth apps.
Security teams should treat the review as a control decision about exposure, privilege, and offboarding readiness. If a vendor can touch production data, token stores, CI/CD pipelines, or admin APIs, the assessment must ask how access is granted, monitored, rotated, and revoked. The OWASP Non-Human Identity Top 10 is useful here because it frames the problem around identity sprawl, secrets exposure, and lifecycle failure rather than paperwork completeness. In practice, many security teams discover the highest-risk vendor access only after an incident forces a search through old integrations and forgotten tokens.
How It Works in Practice
The most effective vendor reviews start with a precise inventory of what the vendor can actually do, not what the questionnaire says it should do. That means identifying the vendor’s NHIs, including OAuth apps, API keys, certificates, service accounts, and automation credentials, then mapping each one to the systems, data classes, and admin functions it can reach. The Ultimate Guide to NHIs is a good baseline for thinking about lifecycle, rotation, and offboarding rather than static trust.
A practical assessment usually follows four questions:
- What exact system, dataset, or workflow does the vendor need access to?
- What identity is used for that access, and is it human-managed or machine-managed?
- How long does the access last, and what revokes it automatically?
- What evidence shows the vendor can no longer reach the asset after termination?
This is where policy and enforcement matter more than narrative. Current guidance suggests using least privilege, just-in-time access, and short-lived secrets wherever the integration allows it. The vendor should not retain standing access simply because the contract is active. Mature teams also verify whether the vendor supports logging, rotation, and offboarding notifications, because those controls determine whether the relationship can be managed safely over time. NHI breaches frequently follow the same pattern: a vendor integration remains live after scope changes, and the residual token becomes the easiest path into the environment.
For governance, use questionnaires as intake, then validate the answers with actual system evidence from IAM, PAM, secrets management, and cloud logs. These controls tend to break down when vendors rely on long-lived tokens embedded in scripts, CI/CD jobs, or legacy integrations that cannot support short-lived credentials.
Common Variations and Edge Cases
Tighter vendor controls often increase integration overhead, so organisations have to balance risk reduction against business continuity and implementation effort. That tradeoff is especially visible in legacy SaaS, managed service providers, and embedded software where the vendor does not support modern lifecycle controls. In those cases, best practice is evolving, and there is no universal standard for every exception path yet.
One common edge case is a vendor that needs broad operational visibility but not broad write access. Security teams may accept read-only telemetry access, but still require explicit scoping, time-bounded tokens, and monitored break-glass paths. Another is indirect access through a subcontractor or marketplace app, where the primary vendor questionnaire misses the actual identity path. The 52 NHI Breaches Analysis and the Reviewdog GitHub Action supply chain attack both illustrate why downstream integrations can matter more than the vendor’s own security posture.
For higher-risk vendors, current guidance suggests requiring offboarding proof, rotation evidence, and an owner inside the business who can remove access without waiting for procurement. If those conditions cannot be met, the right outcome is often to reduce scope or reject the integration, not to score it higher on paper.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and CSA MAESTRO address the attack and risk surface, while NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Vendor access reviews must identify exposed NHIs and their true privilege scope. |
| CSA MAESTRO | MAE-02 | Third-party integrations need lifecycle and access governance across machine identities. |
| NIST AI RMF | Risk-based decisions fit AI RMF governance when vendors operate autonomous tooling. |
Use governance checkpoints to tie vendor access approvals to real operational risk and accountability.
Related resources from NHI Mgmt Group
- How should security teams handle standing access for third-party vendors?
- How should security teams use AI in third-party risk management without over-automating decisions?
- How should security teams implement automated third-party risk mitigation without losing governance control?
- How should security teams reduce duplicate SaaS subscriptions without losing control of access?
