Shared accounts make it difficult to prove who performed a specific action, which weakens both accountability and audit evidence. In a plant environment, that ambiguity spreads across logs, privileged actions, and incident review. Even if production continues smoothly, the organisation cannot reliably demonstrate control over CUI access.
Why This Matters for Security Teams
Shared accounts are not just a convenience problem in manufacturing, they are a control failure that breaks the audit trail. When multiple operators, engineers, or contractors use the same credential, the organisation loses reliable attribution for privileged actions, exception handling, and access to CUI. That makes it harder to satisfy evidence requirements under frameworks like the NIST Cybersecurity Framework 2.0 and to defend decisions during investigations or assessments.
The issue is magnified in plants where uptime pressure encourages shared access to HMIs, maintenance consoles, and service dashboards. NHI Management Group’s Ultimate Guide to NHIs — Regulatory and Audit Perspectives notes that 80% of identity breaches involved compromised non-human identities such as service accounts and API keys, which is a reminder that weak identity discipline often extends beyond people into machine access as well. In practice, many security teams discover the compliance gap only after a plant event, audit request, or production incident has already exposed it.
How It Works in Practice
Compliance problems arise because shared accounts collapse three things auditors care about: attribution, least privilege, and revocation. A single account used by several technicians cannot prove who approved a change, who viewed a record, or who performed a privileged override. That ambiguity creates friction in investigations and makes access reviews largely ceremonial. The result is usually a gap between what the plant says it controls and what the logs can actually prove.
Manufacturing environments often rely on shared access for legacy PLCs, vendor support sessions, or shift-based operations. Current guidance suggests replacing that pattern with named identities, role-based assignment, and step-up controls for sensitive actions. Where that is not yet possible, organisations should segment access by task and record identity context at the point of action. NHI Management Group’s Top 10 NHI Issues is useful here because the same operational blind spots that affect service accounts also show up in shared operational credentials.
- Use named user accounts for operators and engineers wherever the system supports it.
- Require unique sign-in for privileged actions, even if the session is running on shared equipment.
- Log who initiated, approved, and executed each sensitive change.
- Restrict vendor access to time-bound, ticket-linked sessions.
- Map shared-account exceptions to formal risk acceptance and review them on a schedule.
When shared accounts cannot be eliminated immediately, compensating controls should focus on strong session logging, shift-based handoff procedures, and rapid deprovisioning of temporary access. These controls tend to break down in plants with aging OT systems that cannot support individual authentication or produce tamper-evident logs.
Common Variations and Edge Cases
Tighter identity controls often increase operational overhead, requiring organisations to balance auditability against production continuity. That tradeoff is real in manufacturing, especially on equipment that was never designed for modern identity governance. Best practice is evolving, but there is no universal standard for how to retrofit perfect attribution into every legacy control system.
One common edge case is emergency maintenance. Teams sometimes justify shared access so a night-shift technician can restore a line quickly, but that exception still needs traceability through badge-based sign-in, dispatch records, or controlled break-glass access. Another case is vendor support, where a shared account may be easier to manage but is difficult to defend during a compliance review unless it is tightly time-boxed and supervised. The Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs helps frame why lifecycle controls matter even when access is operationally necessary.
Shared accounts are also more defensible on paper when the system is isolated, but that argument weakens as soon as the account can reach regulated data, remote support tools, or production systems connected to enterprise networks. In those cases, compliance teams should treat the account as a shared control exception, not a normal operating model.
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 address the attack and risk surface, while NIST CSF 2.0 and NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | PR.AC-1 | Shared accounts obscure identity and access accountability in plant systems. |
| OWASP Non-Human Identity Top 10 | NHI-01 | Shared credentials create unmanaged identity risk and poor attribution. |
| NIST AI RMF | Governance and accountability are core to managing identity-related operational risk. |
Inventory every shared account, assign ownership, and retire any credential that cannot be uniquely traced.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on June 24, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
