Why do vendors and contractors weaken zero trust if they are not included in PAM?

Why This Matters for Security Teams

zero trust only works when the policy boundary includes every identity that can touch production, not just employees. Vendors and contractors often arrive through exceptions, but exceptions become durable access paths: shared accounts, broad entitlements, ticket-based approvals, and standing credentials that bypass normal PAM workflows. That is where zero trust starts to erode. NIST’s NIST SP 800-207 Zero Trust Architecture is clear that access should be continuously evaluated, not assumed after onboarding.

NHI Management Group research shows why this matters operationally: 92% of organisations expose NHIs to third parties, and 90% of IT leaders say proper NHI management is essential for a successful zero-trust implementation, according to the Ultimate Guide to NHIs. Vendor and contractor access often sits in the same risk class as service accounts and API keys because it can persist beyond the business need that justified it. If PAM is bypassed, the organisation preserves implicit trust for identities that should have the same scrutiny as any other privileged access path. In practice, many security teams discover this only after a third-party account has already been used to move laterally or reach a sensitive admin function.

How It Works in Practice

PAM weakens zero trust when vendors are managed outside the same control plane as internal privileged users. The practical fix is not to add a separate vendor process, but to bring external identities into the same authentication, approval, session control, and audit model. Current guidance suggests treating vendors as high-risk privileged actors with narrowly scoped, time-bound access, rather than as a special class with standing exceptions.

That usually means combining identity proofing, just-in-time elevation, session recording, and rapid revocation. For vendors who need machine access, workload identity is often the cleaner pattern than long-lived shared secrets. The Guide to SPIFFE and SPIRE is useful here because it frames identity around cryptographic proof of what the workload is, not around static passwords or copied API keys. For human contractors, the same principle still applies: no standing privilege, no unmanaged shared accounts, and no access path that bypasses conditional policy checks.

A workable control stack usually includes:

• Single policy engine for employees, vendors, and contractors.
• Just-in-time access with short TTLs and automatic revocation.
• Step-up approval for sensitive actions, not for broad account creation.
• Session logging and command-level visibility for privileged activity.
• Explicit offboarding for every external identity and every related secret.

These controls align with the operating model described in the Ultimate Guide to NHIs — Standards, where lifecycle governance, rotation, and revocation are treated as core security functions rather than administrative afterthoughts. These controls tend to break down when vendors retain emergency access for long periods because revocation becomes culturally difficult and technically inconsistent.

Common Variations and Edge Cases

Tighter vendor PAM often increases friction, requiring organisations to balance operational continuity against reduced exposure. That tradeoff is real, especially for maintenance providers, SaaS implementers, and outsourced administrators who need occasional access across many environments. Best practice is evolving, but there is no universal standard for allowing exceptions without weakening zero trust; the safer pattern is to make exceptions explicit, short-lived, and fully monitored.

One common edge case is third-party support teams that demand shared credentials “for speed.” That approach should be rejected because it destroys accountability and complicates revocation. Another is service providers that need API access to support integrations; those should be handled with distinct machine identities, scoped tokens, and lifecycle controls rather than human vendor accounts. The BeyondTrust API key breach illustrates how privileged access paths can be abused when secret handling is too permissive, while the Schneider Electric credentials breach shows how exposed credentials can turn a narrow access requirement into a broader compromise.

For organisations with multiple business units, the biggest mistake is allowing each team to invent its own contractor access model. That fragments enforcement and creates hidden trust zones, especially where vendor accounts are tied to legacy admin tools or separate approval chains. In those environments, zero trust fails because policy is no longer uniform across the identities that matter most.

Related resources from NHI Mgmt Group

• Why does vendor access weaken zero trust programmes in practice?
• Why do non-human identities complicate zero trust architecture?
• Why do non-human identities increase zero trust risk?
• Why do NHIs complicate zero trust and least privilege efforts?