Why do third-party relationships complicate identity and access management?

Why This Matters for Security Teams

Third-party access is difficult because it stretches identity governance beyond the organisation’s direct employment boundary. A vendor may touch SaaS, cloud APIs, on-prem systems, support channels, and CI/CD tooling, so one relationship can create many non-human identities, secrets, and approval paths. That is why the risk is not just “who got access,” but “who can still use it, through which pathway, and under what business justification.” NHIMG notes that 92% of organisations expose NHIs to third parties, a reminder that supply chain exposure is now part of routine IAM rather than an edge case, as discussed in the Ultimate Guide to NHIs and the Top 10 NHI Issues. Current guidance from the OWASP Non-Human Identity Top 10 and the NIST Cybersecurity Framework 2.0 points toward least privilege, continuous monitoring, and lifecycle control, but third parties make each of those harder to sustain. In practice, many security teams encounter stale vendor access only after an audit, outage, or breach has already exposed the gap, rather than through intentional review.

How It Works in Practice

Third-party IAM becomes complex because different parts of the relationship are owned by different teams. Procurement may approve the contract, application owners may grant entitlements, cloud teams may issue workload tokens, and security may never see the full path. The result is fragmented accountability. A mature program treats the vendor as a governed identity boundary, not a one-time onboarding event. Practically, that means binding each third-party use case to a named owner, a business purpose, a time limit, and a revocation path. For non-human access, the preferred pattern is short-lived secrets, JIT provisioning, and workload identity instead of long-lived static credentials. That shift matters because the credential, not the human, is often the attack surface. NHIMG’s 52 NHI Breaches Analysis shows how frequently identity and secrets misuse drives real incidents, and the lifecycle view in the NHI Lifecycle Management Guide is useful for mapping approval, rotation, and offboarding to the relationship itself. Useful control points include:

• Use intent-based, context-aware authorisation for each request instead of broad standing roles.
• Issue ephemeral credentials per task and revoke them automatically when the task ends.
• Prefer workload identity mechanisms, such as signed tokens, over shared API keys.
• Review access against actual data paths and tool chains, not just the original contract.

These controls tend to break down when vendors share credentials across customers or when integrations are embedded in legacy systems that cannot enforce short-lived tokens.

Common Variations and Edge Cases

Tighter third-party controls often increase operational overhead, requiring organisations to balance security gain against integration friction and support latency. That tradeoff is real, especially when a supplier needs emergency access, runs batch jobs across multiple environments, or supports a product through nested subcontractors. In those cases, the access model can drift from least privilege unless there is continuous evidence of necessity. The biggest edge case is when third parties are not “vendors” in the traditional sense. Managed service providers, software publishers, contractors, and automation platforms may all require access, but their identity patterns are different. Some need human-authenticated access with strong PAM controls; others need machine identities with short-lived secrets; others need both. Best practice is evolving here, and there is no universal standard for every vendor class yet, but guidance from Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs and the Cisco DevHub NHI breach shows why lifecycle discipline matters when external access is coupled to production systems. The key operational mistake is assuming contract expiry equals access expiry. In reality, secrets persist, tokens remain valid, and API paths stay reachable unless revocation is explicit and verified. That is why third-party IAM is really a continuous assurance problem, not a one-time approval problem.

Related resources from NHI Mgmt Group

• Why do service accounts and third-party identities complicate compliance reviews?
• Who should own third-party access risk in a banking GRC programme?
• What is the difference between workload identity and workload access management?
• Why do machine identities complicate identity posture management?