OT Asset Discovery

OT asset discovery ensures organisations have a clear and accurate understanding of what is actually running within their operational environments.

As operational technology (OT) systems become increasingly connected — bringing together legacy equipment, modern control networks, remote access, and IT interfaces — maintaining visibility of OT environments has become more complex. OT asset discovery provides the foundation for understanding what systems are in place, how they are connected, and where potential risks may exist.

For many organisations, asset discovery is the logical starting point when it comes to implementing OT cyber security in manufacturing. Without a clear view of assets and connections, it is difficult to make informed decisions about protection, risk, or compliance.

What is OT asset discovery?

OT asset discovery is the process of identifying, cataloging, and understanding all devices, systems, and connections within an operational technology environment.

This includes a wide range of assets, such as programmable logic controllers (PLCs), human–machine interfaces (HMIs), sensors, remote terminal units (RTUs), engineering workstations, servers, network devices, and the communication paths between them.

These environments are often complex and shaped by operational priorities rather than documentation or visibility. This creates a common set of challenges that need specialised knowledge and deep experience to overcome.

Because the end goal of OT asset discovery is not simply to produce a list of equipment – there’s a difference between OT asset inventory and OT asset discovery. A meaningful discovery exercise provides context: what devices exist, how they communicate, what software or firmware they run, how critical they are to operations, and how they interact with other systems.

Why OT asset discovery matters

Without a clear picture of your assets, you can’t effectively protect them. OT environments often evolve over decades — with equipment added, upgraded or reconfigured by different teams or vendors — and documentation rarely keeps pace. This creates blind spots that attackers can exploit and that make risk management difficult.

An OT asset discovery exercise addresses this by giving organisations complete visibility into their operational landscape. That visibility brings several key advantages:

• Informed protection: You can’t defend what you can’t see. Asset discovery reveals every device connected to your network — including those you may have forgotten about or never documented.
• Reduced risk: Unknown or unmanaged devices often represent the greatest vulnerabilities. Identifying them allows you to patch, isolate or replace them before they cause problems.
• Compliance and accountability: Directives such as NIS2 and other OT security frameworks require organisations to demonstrate control and awareness of their assets.
• Faster response: Knowing what’s on your network allows for quicker containment and recovery in the event of an incident.
• Smarter investment: Understanding your environment helps prioritise cybersecurity budgets based on actual risk, not assumptions.

Many organisations are surprised by what asset discovery uncovers. We’ll often find legacy systems, vendor access pathways, or outdated firmware that are still operational, as well as existing documentation does not reflect how systems are actually connected or configured.

How OT asset discovery is carried out

While every environment is different, OT asset discovery typically follows a structured approach designed to maximise accuracy while minimising disruption. A range of OT asset discovery software can be used during the process.

1. Scoping the environment

The first step is to define what is in scope. This includes identifying which sites, networks, and systems will be included, as well as clarifying the level of detail required. Clear scoping helps ensure discovery efforts focus on operationally relevant areas.

2. Data collection

Information is gathered using a combination of non-intrusive techniques, such as passive network monitoring, review of existing documentation, and, where necessary, physical walkdowns or discussions with engineering teams.

In OT environments, a passive approach is usually preferred. Passive discovery observes network traffic to identify devices and communication patterns without actively querying systems, reducing the risk of disruption to live operations.

3. Analysis and correlation

Collected data is analysed to build a coherent picture of the environment. Devices are identified and categorised, duplicate records removed, and missing information filled where possible. This step often highlights outdated systems, insecure protocols, or unexpected connections.

4. Validation

Findings are reviewed with operational teams to ensure accuracy. Validation is important because real-world configurations do not always match documentation or assumptions.

5. Reporting and outputs

A good OT asset discovery report should be presented in a clear, usable format that reflects both technical detail and operational context.

What you typically receive from an OT asset discovery exercise

The output of OT asset discovery is a set of practical deliverables that can be used by both technical and non-technical stakeholders.

These commonly include:

• An OT asset inventory
• A structured record of identified devices, including type, role, connectivity, and relevant technical details.
• Network and communication visibility. Diagrams or mappings that show how systems interact and where dependencies exist.
• Initial risk insights. Identification of outdated systems, insecure connections, or areas requiring further investigation.

Together, these outputs provide a reliable baseline for understanding the operational environment as it actually exists today.

How long OT asset discovery takes and what it involves for you

The duration of an OT asset discovery exercise depends on the size and complexity of the environment. For many small and medium-sized industrial organisations, discovery can typically be completed within a few weeks.

From the organisation’s perspective, involvement is usually limited. The process is designed to run alongside normal operations, with minimal disruption. Input may be required to confirm scope, provide access to documentation, or validate findings, but day-to-day operational impact is kept low.

Where OT asset discovery fits in the OT security journey

When to carry out OT asset discovery is almost as important as how you do it. It’s best viewed as a foundation rather than an end goal. A typical improvement journey often follows this progression:

• Establish visibility through asset discovery
• Use that visibility to assess risk
• Implement proportionate security controls
• Maintain visibility as environments evolve

Starting with asset discovery ensures that later decisions are based on accurate information. Without this foundation, organisations risk investing in security measures that only address part of the problem.

Taking the first step

In modern industrial environments, uncertainty is one of the biggest sources of risk. OT asset discovery replaces that uncertainty with clarity, giving organisations a factual understanding of their operational systems and how they are connected.

For organisations beginning their OT security journey, asset discovery provides a structured, low-risk way to establish visibility and build confidence in next steps — whether those involve risk assessment, segmentation, or longer-term security improvement. For more information, take a look at our OT asset discovery service, or book a free consultation call to talk with one of our team.