Why do shared vendor credentials increase risk in manufacturing environments?

Why This Matters for Security Teams

Shared vendor credentials are dangerous in manufacturing because they turn a controlled third-party relationship into an untraceable access channel. Once a password is reused across technicians, shifts, or vendors, the security team loses the ability to prove who accessed a PLC, historian, MES, or design repository at a given moment. That undermines incident response, auditability, and accountability at the exact point where operational impact is highest.

This is not just an IAM hygiene issue. The OWASP Non-Human Identity Top 10 treats secret misuse and weak lifecycle control as recurring failure modes because credentials are often copied, cached, and shared beyond their intended scope. NHIMG research shows the same pattern at scale: the Guide to the Secret Sprawl Challenge highlights how secrets spread once they leave a controlled workflow, and the 2024 Non-Human Identity Security Report found that 23.7% of organisations still share secrets through insecure methods such as email or messaging applications.

In practice, many security teams discover the problem only after a vendor account has already been abused, rather than through intentional access review.

How It Works in Practice

In manufacturing environments, vendor access often reaches systems that are both operationally sensitive and difficult to segment cleanly. Shared credentials make that risk worse because they erase the link between identity, task, and time. If a maintenance contractor, OEM support engineer, and systems integrator all use the same login, the organisation cannot reliably answer basic questions such as which session changed a recipe, downloaded a backup, or disabled an alarm.

Best practice is to replace shared access with named identities, scoped privileges, and short-lived credentials issued only for a specific maintenance window. Where possible, access should be brokered through privileged access management, strong authentication, and session recording so each action is tied to a person and a task. For non-human access, the current guidance suggests using dynamic secrets with strict TTLs rather than static passwords that persist across jobs. The Ultimate Guide to NHIs — Static vs Dynamic Secrets is useful here because it distinguishes between credentials that are merely stored safely and credentials that are intentionally short-lived.

Manufacturing teams should also align vendor access with zero trust principles and review it through the same access governance lens used for internal users. That means each request should be evaluated in context: who is requesting access, which asset is being reached, whether the request matches an approved service ticket, and how long the session should last. The NIST Cybersecurity Framework 2.0 is helpful for structuring these controls across identify, protect, detect, and respond functions, while NIST SP 800-63 Digital Identity Guidelines reinforces the importance of strong authentication and lifecycle management.

• Issue unique accounts for every vendor person, not one shared login per company.
• Use just-in-time access with automatic expiry after the approved task.
• Record and review privileged sessions for OT and production systems.
• Rotate any exposed secrets immediately and remove dormant vendor accounts.

These controls tend to break down when vendors need emergency access to legacy OT equipment that cannot support modern authentication or session controls.

Common Variations and Edge Cases

Tighter vendor access control often increases operational overhead, requiring organisations to balance production uptime against stronger accountability. That tradeoff is most visible in plants with 24/7 support agreements, older PLC estates, or vendors that insist on remote service through fixed credentials.

There is no universal standard for how quickly all shared access can be eliminated in brownfield manufacturing, but current guidance suggests prioritising the highest-risk pathways first: internet-facing remote access, privileged OT accounts, and credentials used by multiple external parties. Where a shared login cannot be removed immediately, organisations should isolate it behind a jump host, restrict time windows, enforce change-ticket approval, and rotate the credential after every use. That is a transitional control, not a target state.

NHIMG research on the 2024 Non-Human Identity Security Report shows the maturity gap is still wide, and only 19.6% of security professionals express strong confidence in securely managing non-human workload identities. That lack of confidence matters in manufacturing because vendor access is often treated as a convenience layer instead of a governed identity domain. The goal is not to block support work, but to make every support action attributable, time-bound, and revocable.

Related resources from NHI Mgmt Group

• What breaks when vendor access is not inventoried in manufacturing environments?
• Why is contractor access such a high-risk issue in manufacturing environments?
• Why do shared mobile devices create identity risk in clinical environments?
• Why do shared vendor credentials create such a serious compliance problem?