Cyber security | 27 January 2026

The challenge of unknown assets in OT environments

In operational technology (OT) environments, OT asset visibility is often overlooked, even though cyber security risks don’t always come from sophisticated attacks or zero-day vulnerabilities. In many cases, the biggest risk is much simpler: not knowing what assets are actually connected to the network.

OT asset visibility remains one of the most common and persistent challenges across industrial environments. Unknown, unmanaged, or poorly documented assets can quietly introduce security gaps, operational risk, and compliance issues, often without anyone realising until something goes wrong.

Why OT environments struggle with asset visibility

Unlike IT environments, OT systems often:

• Include legacy equipment still critical to operations
• Rely on vendor-managed or third-party systems
• Have grown organically over many years
• Were never designed with cyber security in mind

As a result, many organisations struggle to maintain a complete and accurate OT asset inventory. Assets may be missing from documentation, incorrectly classified, or completely unknown to the teams responsible for securing them.

What are “unknown” OT assets?

Unknown OT assets can take many forms, including:

• Legacy controllers or HMIs still in operation
• Temporary systems left behind after projects or upgrades
• Engineering laptops connected intermittently
• Vendor-installed devices not formally handed over
• Shadow OT introduced outside standard processes

These assets are rarely malicious by design, but they often operate outside normal monitoring, patching, or change management processes, making them risky by default.

Why unknown assets increase OT cyber security risk

When OT asset visibility is incomplete, organisations face several risks:

1. Security blind spots

If an asset isn’t known, it isn’t monitored. This means vulnerabilities, misconfigurations, or suspicious activity can go undetected.

2. Unmanaged vulnerabilities

Unknown assets may be running outdated firmware or unsupported operating systems, increasing exposure to known threats.

3. Unauthorised changes

Assets that aren’t tracked properly are more likely to experience configuration changes without an audit trail, increasing the risk of outages or safety incidents.

4. Incident response delays

During an incident, incomplete asset information slows down investigation and recovery, directly impacting operational resilience.

OT asset visibility vs traditional IT visibility

Many organisations attempt to apply IT security tools to OT environments, expecting the same level of visibility. However, IT and OT systems behave very differently.

OT asset visibility requires:

• Awareness of industrial protocols
• Context around asset function and criticality
• Understanding of operational dependencies
• Minimal disruption to live systems

Without OT-specific visibility, teams may see that an asset exists, but not what it does, why it matters, or how risky it is.

The link between asset visibility and operational resilience

OT cyber security isn’t just about preventing attacks, it’s about keeping operations running safely and reliably.

When organisations improve OT asset visibility, they gain:

• Better risk prioritisation
• Faster incident response
• Clearer change management
• Stronger compliance posture
• Reduced unplanned downtime

In other words, asset visibility directly supports operational resilience, not just security metrics.

How organisations can improve OT asset visibility

Improving OT asset visibility doesn’t require ripping out existing systems. Practical steps include:

• Establishing and maintaining a central OT asset inventory, aligned with recognised best practice guidance
• Maintaining asset inventory in a secure, auditable solution rather than relying on spreadsheets
• Tracking configuration changes over time
• Classifying assets by criticality, not just type
• Ensuring visibility across sites and environments

Most importantly, visibility should be continuous, not a one-off exercise.

Final thoughts

OT asset visibility remains one of the most overlooked aspects of industrial cyber security. Unknown assets may seem harmless, but they often represent the largest unmanaged risk within OT environments.

By focusing on visibility first, organisations can make more informed decisions about security, compliance, and resilience, and reduce the likelihood of unpleasant surprises down the line.