At a large manufacturing plant in Northern Europe, a routine maintenance task nearly became a shutdown.
An external vendor needed temporary access to adjust a controller. The engineer on site could not create a new account in time, so a shared password was used instead. The work was completed, but weeks later that same credential was discovered circulating among several subcontractors.
Nothing malicious happened. Yet the organisation had no reliable way to know who had accessed which system, or when. From a compliance perspective, it was already a failure.
This story is not exceptional. Variations of it happen every day across utilities, factories, transport networks, and critical infrastructure. It illustrates a simple truth: OT access control often fails not because of bad intentions, but because of bad design.
Most authentication models were built for office IT environments. They assume stable networks, modern endpoints, and the ability to update systems frequently. OT environments operate under very different rules.
Industrial systems are long-lived, isolated, and difficult to modify. Safety procedures restrict changes. Networks are segmented or disconnected by design. External contractors come and go. Uptime is non-negotiable.
When access control is designed around IT assumptions, friction and risk inevitably appear. Password policies become unmanageable. VPN accounts are reused. Privileges accumulate over time. Logs provide only partial visibility.
The result is a paradox: organisations invest heavily in cybersecurity, yet the practical mechanisms for granting and controlling access remain fragile.
Many companies respond to these weaknesses by adding more layers: stronger passwords, additional approvals, tighter remote access rules. While well intentioned, these measures rarely address the core issue.
The underlying architecture of most OT authentication still relies on static credentials — reusable usernames, passwords, and long-lived accounts. Once such credentials are issued, they continue to hold value long after the original task is complete.
In an environment where a single action can halt production or disrupt essential services, this model is fundamentally misaligned with operational risk.
What OT requires is a different mindset: access should be temporary, contextual, and verifiable — not permanent and portable.
To design access control that fits OT, it helps to step away from technology for a moment and observe how maintenance and operations really happen.
A typical day on the plant floor looks like this:
These are concrete tasks, limited in scope and time. Yet many organisations still manage them with credentials that remain valid indefinitely.
A more realistic model begins by asking different questions:
When access is treated as a single, bounded event rather than an ongoing entitlement, security improves without adding operational burden.
Another reality shapes every OT site: connectivity cannot be assumed.
Maintenance often occurs in isolated networks, remote substations, or during outages. In these situations, authentication that depends on central servers becomes unusable at the very moment it is needed most.
Effective OT access control must therefore be able to operate independently — allowing approvals to be verified locally, expiring automatically, and leaving trustworthy records even when systems are disconnected.
This requirement explains the growing interest in dynamic, one-time authorisation approaches. Technologies such as OTAC embody this principle by enabling action-bound approvals that can be validated without relying on constant connectivity. The goal is not to introduce new complexity, but to remove the inherent weakness of reusable credentials.
Modern regulations are raising the bar for accountability. Frameworks like NIS2 and IEC 62443 demand more than proof that someone logged in. They require evidence of what was actually done.
In OT, a useful access control system must therefore generate clear, tamper-evident traces:
When this information is created automatically at the moment of access — rather than reconstructed later from scattered logs — both security and compliance improve.
Authentication in OT is not only a gatekeeper. It is also a primary source of operational evidence.
Every improvement to OT security faces the same constraint: it must not disrupt production.
The most practical approaches share common characteristics. They can be layered onto existing infrastructure, require minimal changes to legacy equipment, support contractors naturally, and continue to function during network disruptions.
Most importantly, they reduce reliance on shared accounts and long-lived credentials without forcing radical transformation. Security advances gradually, aligned with real maintenance cycles and operational priorities.
This balance between protection and practicality is where many IT-centric tools fall short — and where OT-specific thinking becomes essential.
Strengthening OT access control does not require a massive overhaul. It requires a change in focus.
Begin by identifying where reusable credentials create the greatest risk. Replace standing privileges with task-based approvals. Ensure that access can be verified locally. Capture reliable evidence for every critical action.
These are not abstract cybersecurity goals. They are operational improvements that directly support uptime, safety, and regulatory compliance.
As industrial environments become more connected and collaborative, access control will remain the most critical intersection between people and machines.
The lesson from countless real-world incidents is clear:
security in OT is ultimately about controlling actions, not protecting passwords.
Organisations that design authentication around this principle will be better prepared for the realities of 2026 and beyond — resilient when networks fail, confident during audits, and protected against the everyday risks of modern operations.
Access control that fits OT reality is not a luxury.
It is the foundation of reliable industry.
--------------------
swIDch will continue its quest to innovate and pioneer next-generation authentication solutions. To stay up-to-date with the latest trends sign up to our newsletter and check out our latest solutions.