Why do shared credentials and static passwords create such high risk in industrial control systems?

Why Shared Credentials Become an OT Security Blind Spot

industrial control systems are unforgiving when identity is vague. Shared passwords on engineering workstations, HMIs, PLC maintenance paths, and vendor remote access accounts remove attribution, so operators cannot tell who changed a setpoint, altered logic, or copied a configuration file. That makes incident response slow and forensic reconstruction weak. It also turns one exposed password into a reusable key across systems, which is exactly the kind of failure the Guide to the Secret Sprawl Challenge warns about.

For OT teams, the risk is not just unauthorized login. Static passwords tend to linger because uptime, vendor support, and legacy protocol constraints encourage exceptions that never get retired. Once a credential is shared across shifts or plants, accountability collapses and privilege boundaries blur. Current guidance from the NIST Cybersecurity Framework 2.0 points to stronger asset and access governance, but industrial environments still struggle to apply it consistently. In practice, many security teams discover shared access only after a maintenance credential has already been reused outside its intended scope.

How Static Passwords Turn Routine Access into Systemic Risk

Static passwords are high risk in ICS because they behave like standing authority. If the password is valid this month, it is likely valid next month, which gives attackers time to harvest it, replay it, and move laterally. In an environment where one account may unlock remote support, local console access, and admin functions, a single compromise can cascade into process disruption or safety impact. The issue is amplified when passwords are embedded in scripts, stored on shared jump hosts, or exchanged by email and messaging.

Security teams should treat identity in OT as a control problem, not only a login problem. Stronger practice means unique accounts where feasible, short-lived access for maintenance, centralized session logging, and rapid credential revocation when a task ends. The NIST identity guidance is useful here because it reinforces that authentication strength alone is not enough if the credential never changes and cannot be tied to a person or workflow. NHIMG research on The 2024 Non-Human Identity Security Report found that 88.5% of organisations say their non-human IAM practices lag behind or are merely on par with human IAM, which fits the OT pattern of static access outliving its original purpose.

• Replace shared logins with named accounts wherever the device and process allow it.
• Use just-in-time access for vendors and maintenance staff instead of permanent passwords.
• Rotate secrets after every job, not on a calendar that ignores actual use.
• Log command activity, not just successful authentication, so changes can be traced.

These controls tend to break down in brownfield plants where legacy controllers, proprietary vendor tools, and 24/7 uptime requirements prevent rapid credential replacement.

Where the Standard Answer Breaks Down in Real Plants

Tighter access controls often increase operational overhead, so organisations have to balance resilience against maintenance speed and vendor support demands. That tradeoff is real in industrial sites, where technicians may need emergency access at odd hours and equipment may not support modern identity features. Best practice is evolving, and there is no universal standard for this yet, but the direction is clear: reduce standing privilege, shorten credential lifespan, and make every exception explicit.

Some environments can move faster by separating remote access from control-plane access, using jump hosts, and enforcing approval workflows before a password is released. Others need compensating controls because the device itself cannot change. In those cases, password vaulting, session brokering, and strict post-use rotation become the practical baseline rather than an ideal. The deeper problem is not only exposure, but reuse across plants, vendors, and shared maintenance workflows. That is why the The 2024 ESG Report: Managing Non-Human Identities matters: it shows compromised non-human identities are already producing repeated incidents across enterprises, which is exactly the pattern shared credentials enable in OT.

For this reason, the most resilient programmes treat static passwords as a temporary exception, not an acceptable operating model.

Related resources from NHI Mgmt Group

• Why do stolen credentials create such high risk in cloud identity attacks against SaaS and IdPs?
• Why do misconfigured vendor credentials and overly broad permissions create such high risk in integrations?
• Why do shared privileged passwords create such high audit risk?
• Why do shared vaults create risk when organisations rely on standing credentials for privileged access?