Why do third-party vendors create extra risk in industrial access models?

Why Third-Party Vendor Access Raises Industrial Risk

Third-party vendors are risky in industrial environments because their access often arrives as an exception and then quietly becomes permanent. In OT and ICS settings, that access is usually broad enough to support emergency maintenance, yet weakly governed across legacy systems, jump hosts, and remote support channels. The result is a standing path into critical operations, not a tightly bounded service relationship.

That risk is amplified when vendor credentials are shared across teams, reused across sites, or left active long after the work ends. The Ultimate Guide to NHIs notes that 92% of organisations expose NHIs to third parties, which is a strong signal that vendor access has become a supply chain issue, not just an account management issue. Industry guidance such as the NIST Cybersecurity Framework 2.0 treats external access as a governance and monitoring problem, because trust without lifecycle control becomes an open invitation.

In practice, many security teams discover vendor exposure only after a maintenance window, audit finding, or incident review reveals how many paths were never removed.

How to Reduce Vendor Risk Without Breaking Operations

The operational answer is not to ban vendor access, but to make it time-bound, scoped, and traceable. Vendor identities should be treated like any other privileged non-human identity: created for a purpose, constrained to a task, and revoked when the task is complete. Current guidance suggests combining strong identity proofing with workflow approvals, short-lived access, and continuous logging so that support activity can be reviewed after the fact.

Practitioners should separate the vendor relationship from the credential itself. A contract may authorize support, but the credential should still be issued just in time, bound to a specific session, and protected by MFA where the environment supports it. The OWASP Non-Human Identity Top 10 and NHIMG research both point to the same failure pattern: long-lived secrets, excessive privilege, and incomplete offboarding are what turn routine support into persistent exposure. The 52 NHI Breaches Analysis reinforces that compromises are often not caused by sophisticated exploitation alone, but by credentials that remained usable longer than they should have.

• Use named vendor identities instead of shared accounts.
• Issue time-limited access tied to a ticket, change window, or approved session.
• Store and rotate secrets centrally rather than embedding them in scripts or email.
• Log command, file, and session activity for post-event review.
• Revoke access automatically when maintenance closes or the contract changes.

These controls tend to break down when OT assets require direct vendor support on flat networks because the environment cannot enforce session scoping or reliable revocation.

Where Industrial Vendor Models Commonly Fail

Tighter vendor controls often increase operational friction, requiring organisations to balance uptime against access assurance. That tradeoff is real in industrial environments where outages are expensive and some systems are too old to support modern identity controls. Best practice is evolving, but there is no universal standard for this yet, especially where remote support must coexist with legacy PLCs, proprietary HMIs, and fragile change windows.

The most common edge case is emergency access. If a vendor must respond outside a planned window, organisations often fall back to standing accounts or overbroad privileges so production can continue. Another common failure is poor offboarding: when a supplier relationship ends, access is assumed to be harmless and remains active. NHIMG research shows that only 20% of organisations have formal processes for offboarding and revoking API keys, which is a useful warning sign even outside classic API use because the same lifecycle weakness appears in vendor credentials. For teams modernising their approach, the Ultimate Guide to NHIs — Key Challenges and Risks is a practical reference for moving from durable access to lifecycle control.

In short, industrial vendor risk persists whenever access is treated as a convenience for operations rather than a governed identity with a defined end date.

Related resources from NHI Mgmt Group

• Why do third-party vendors create identity and access risk?
• When does JIT access create more risk than it reduces?
• Why do third-party vendors create so much identity risk?
• How do third-party SaaS integrations create NHI risk and how should they be managed?