Operational Technology (OT) Security: Challenges, Technologies, and Best Practices

In the past, information security was your main concern. Data could be accessed through your networks and applications by threat actors who were not even on the same continent as you. On the other hand, physical equipment could be secured with a lock and key.

Now, however, physical hardware is monitored, controlled, and connected through digital systems — which means it can be reached, and attacked, remotely. 
As such, OT security is a very valid concern.

Operational technology (OT) security management and its importance

What is operational technology?

Operational technology refers to systems and devices that monitor and control physical processes in the real world. You might have heard of OT alongside IT, but they are two distinct components of technology.
Where information technology (IT) systems manage data and business applications, OT systems manage machines, utilities, production lines, and industrial operations. IT is the technology that manages data and how it flows through your systems, while OT controls the physical components that keep operations going in the real world.
OT environments typically include industrial control systems (ICS) that operate infrastructure such as: 

Power generation plants
Water treatment facilities
Oil and gas operations
Manufacturing processes
Transportation systems

Since these are the physical components that power operations, they can be disrupted or damaged. Operational technology security is the practice of protecting these systems so they remain safe, reliable, and available.

Why do you need operational technology security?

If IT security fails, you risk data exposure; if OT systems security fails, you get: 

Shutdown of utilities
Production line disruption
Equipment malfunction
Safety incidents
Large-scale service outages

As we said earlier, managing the security of physical components was relatively easy in the past. However, now, many OT environments are connected to IT networks, cloud services, and remote access platforms to improve efficiency.  

The attack surface has expanded significantly, and a breach in IT may become a pathway into OT if they are not properly segmented or adequately controlled.

The scale of the risk is hard to ignore. Over 12,000 cybersecurity incidents related to ICS were reported in 2024 alone. Attacks by state-aligned adversaries on energy, transport, and water sectors rose 49% that same year. And the OT security market, a reflection of how seriously organizations are taking this, is valued at $27 billion in 2025, projected to reach $122 billion by 2034.

OT security solutions protect critical infrastructure and prevent operational downtime. Without these security controls, you risk cyber incidents turning into real-world physical consequences. 

Speaking of real-world consequences, how sure are you that your cyber defenses will stand up against an actual attack? If the answer is, “Hmm,” then you should consider our red teaming services.

Difference between IT and OT cybersecurity

Physical disruption vs data theft: IT security primarily focuses on protecting data and digital services. OT information security focuses on preventing physical disruption and unsafe conditions.

Safety and reliability vs confidentiality: IT security prioritizes confidentiality, integrity, and availability of data. OT security, on the other hand, is responsible for the safety, reliability, and continuous operation of physical systems.

Operational availability vs data availability: In IT, downtime may impact productivity and reputation. In OT, downtime can shut down utilities, damage equipment, or create safety risks.

Legacy systems vs modern systems: IT environments are typically updated regularly. OT environments often rely on legacy systems that may run for 10–15 years or longer without major updates.

Patching frequency differences: IT systems are patched frequently. OT systems often have limited patching due to fear of downtime, compatibility issues, or lack of vendor support.

Because reboots or updates are not easily tolerated, OT environment security strategies must focus on segmentation, boundary controls, and monitoring rather than frequent system changes.

For that, you need to know the different parts of OT and how they work together.
 

We have already mentioned how IT covers the information side of things, while OT manages the physical part of your infrastructure. Where IT security focuses on CIA (confidentiality, integrity, availability), OT deems safety and availability most important.

Obviously, the security of the two has different goals and priorities. Let us take a look at them.
 

The core components of operational technology

Planning OT security begins with understanding the components that make up industrial networks and how they connect with each other.

Industrial control systems

ICS is a broad term used to describe systems that monitor and control industrial processes. It is not a single technology, but an umbrella term for several different systems working together.

 These systems connect hardware and software to manage physical operations. They receive data collected from other components and coordinate how it is processed and acted upon. In short, they are the “managers” who ensure that machinery and infrastructure behave as expected.

Supervisory control and data acquisition (SCADA)

SCADA systems are used to monitor and supervise industrial processes at a higher level. They collect data from field devices and consolidate it in a centralized system so operators can monitor distributed equipment easily. 

Additionally, SCADA allows operators to remotely control equipment. Again, this is very useful when you have infrastructure spread over a large geographic area. This is why SCADA systems are commonly found in utilities such as power generation and water management, as well as large manufacturing units.

Programmable logic controllers (PLCs)

PLCs are specialized industrial computers that control machinery and processes at the operational level. They manage inputs and outputs from devices such as sensors, motors, valves, and pumps.  

When they receive input indicating changes in conditions, PLCs execute programmed logic to maintain operational processes.  

Because they directly control physical equipment, they play a critical role in ensuring consistency, precision, and safety within industrial environments.

Human machine interfaces (HMI)

HMIs are the screens and control panels operators use to interact with OT systems. Essentially, they translate complex system data into a visual format that operators can instantly understand. 

As a result, they help operators monitor system performance, respond to alerts, and adjust controls as needed. In short, HMIs make day-to-day operations easier to manage and help identify issues before they escalate.

Distributed control systems (DCS)

Distributed control systems are control architectures where components are distributed throughout the system rather than centralized. This allows control functions to be closer to the processes they are managing.  

As such, they make operations more resilient, reducing the likelihood of a single point of failure disrupting the entire system. That is why they are often used in large industrial facilities, where continuous operations are essential.

OT environments typically follow a layered structure:

IT Network → Firewall/Segmentation → OT Control Layer (SCADA/HMI) → PLCs → Sensors and Physical Devices

Securing these environments is not just about protecting individual systems. Because these components are tightly integrated, you also need to understand how they interact. A vulnerability in a SCADA system, for example, could expose PLCs.  

Not separating systems and controlling how IT and OT interact could allow threats to move from business systems into operational processes. This is why OT security focuses heavily on visibility, segmentation, and controlled access across all layers.

Find out more about the IT and OT threats you can expect in 2026 in our Cybersecurity Trends article.

OT security technologies

Once you understand the OT infrastructure and the security risks it faces, the next step is implementing the right technologies to secure it.
We have seen how this environment has its own set of priorities, and any security solutions must work within strict constraints. As a result, OT security tools focus heavily on visibility, segmentation, and controlled access, rather than frequent system changes.

Network segmentation

Network segmentation is one of the most important security measures in OT environments. By separating IT and OT networks–and further dividing OT into controlled zones—you can limit how systems communicate with each other. 

Keeping these layers separate reduces the risk of lateral movement. Even if one part of the network is compromised, you can prevent the threat from spreading to critical systems like PLCs or control layers.

Industrial firewalls

Network segmentation is the broader strategy, and industrial firewalls are the tools that help you achieve this separation between IT and OT networks. They act as a protective barrier and enforce strict access control at the boundary layers. In short, they ensure that only authorized traffic can pass between different parts of the environment. 

Of course, OT firewalls are not the same as standard IT firewalls; instead, they are designed to understand OT protocols and operate reliably in industrial settings. You can use them to enforce granular rules without disrupting critical processes.

Intrusion detection and prevention systems (IDS/IPS)

The guards and watchdogs of OT security programs, intrusion detection and prevention systems (IDS/IPS) are monitoring systems deployed at network boundaries to detect abnormal or unauthorized activity.

These systems analyze network traffic for unusual patterns to identify potential threats before they can affect operations. You want early detection as part of your defense in OT environments because many of these systems cannot be easily patched.

OT asset management platforms

To know what to secure, you need to know what OT devices exist within the environment, how they are connected, and how they communicate. Asset management platforms provide you with this information.

You especially need it if your OT environment is a mix of modern and legacy equipment. Without a clear inventory, you may find it difficult to assess risk, enforce policies, or respond effectively to incidents.

Secure remote access

You often need remote access for maintenance, monitoring, and vendor support. However, it also introduces significant risk if not properly controlled. 

With secure remote access solutions that use hardened access points, multi-factor authentication, and strict privilege controls, you ensure only authorized users can connect to OT systems. You can also limit access to specific devices and sessions, reducing the likelihood of misuse or compromise.  

What does our cybersecurity expert have to say about protecting your organization from cyber attacks? Safeguarding Against Cybercrime has more information.
 

OT cybersecurity frameworks and standards

NIST CSF 2.0

National Institute of Standards and Technology (NIST) cybersecurity framework (CSF) 2.0, as the name suggests, is a set of guidelines to help organizations manage their cyber risk. Its outcome-based structure makes it applicable across both IT and OT environments — broad enough to cover asset discovery, anomaly detection, and incident recovery regardless of the underlying technology.
NIST CSF 2.0 is built around six core functions: 

Govern
Identify
Protect
Detect
Respond
Recover

As you can see, these are general enough to apply to OT as effectively as to IT. For example, the Identify function aligns quite well with the asset discovery function of OT security, while Detect looks at suspicious activity or abnormal behavior. As such, they provide a repeatable, structured format for systems protection.

Special mention: NIST SP 800-82
The NIST Special Publication 800-82 is a guide to ICS security. It offers guidance on OT-specific security needs and practical controls. If the broad strategy offered by NIST CSF 2.0 seems too abstract, you might find this easier to implement.

IEC 62443 and ISA/IEC 62443

Where NIST CSF 2.0 provides the framework, and NIST SP 800-82 offers implementation guidance, IEC 62443 is a prescriptive, OT-focused, and internationally recognized standard for securing industrial automation and control systems.  

It is often called ISA/IEC 62443, because it was originally developed by the International Society of Automation (ISA) and was later adopted and formalized by the International Electrotechnical Commission (IEC). This naming convention acknowledges its origin and the joint collaboration responsible for maintaining it. 

IEC 62443 provides detailed requirements for system architecture, segmentation, access control, and secure development. It has defined security levels for risk-based decision-making and offers a zones and conduits segmentation strategy to limit unauthorized access and restrict the flow of information.

MITRE ATT&CK for ICS

MITRE ATT&CK® describes itself as “a globally-accessible knowledge base of adversary tactics and techniques based on real-world observations.” This base also lists real-world cyber attack techniques observed in OT environments.  

Where the previous frameworks and standards helped you plan your security strategy, this informs you of how attackers behave when targeting operational technology. If you are interested in learning more about real-world risk, this is where you can find the information. 

You can then use this knowledge to design controls that anticipate how a threat actor would gain access and move through your systems.

OT security best practices

As mentioned earlier, you want stable, uninterrupted services across your OT systems. With IT, you can take the system offline and roll back the update, redeploy, or restore from backup. Operational technology, being connected to equipment in the physical world, is not as easy to “turn off and on again.” 
As such, the main priority when implementing OT security is to minimize disruption as well as reduce risk. Here’s what you need to do:

Maintain complete asset visibility

We said this before, but you cannot secure what you do not know or understand. That is why it is important to be able to see what exists in your environment. You need to have a clear view of the devices, systems, control layers, and how everything connects to each other. 

This asset inventory tells you which systems are most critical, so you can assess risk effectively and apply the appropriate controls.

Segment networks and control communication

One of the most important ways to reduce risk in your OT environment is to keep the various layers separated. It is not enough to just keep IT separate; even OT should be divided into controlled zones. 

Segmentation helps limit unwanted communication between systems, which, in turn, limits the lateral movement achievable, even if one part of the system is compromised. Even if a threat actor gains access, they are less likely to use that to infiltrate other, more critical layers.

Secure and restrict access

Implement a Zero-Trust architecture for better security. Strict identity and access management is as important, maybe even more, for OT as it is for IT. You need to limit it to authorized users and devices for approved systems, especially in the case of remote access, which is often used for maintenance and vendor support.
 
For critical systems, you may want to harden the device, enforcing multi-factor authentication and least-privilege access.

Monitor continuously to detect anomalies

IT security uses patches to fix any vulnerabilities, bugs, or performance issues. OT systems cannot be patched that easily, because it can be risky or disruptive. As such, continuous monitoring is necessary for defense.  

You need to keep an eye out for anomalous behavior that could indicate a potential threat. That allows you to respond before it develops into a serious issue that can cause disruption or worse.

Adapt security to operational constraints

OT environments often have legacy systems that are difficult to update or take offline. As such, you need to rely on compensating controls to manage risk. Access control is one such measure, but you may also need strong boundary protections. This is when it is important to prioritize systems based on criticality and risk, so you can design appropriate security measures for them.

Prepare for incidents

No amount of planning can guarantee complete security. You can have incidents even with stringent measures in place. Instead of trying to fix things after the fact, have a recovery plan in place. This defines roles and responsibilities, so everyone is aware of what they need to do. A clearly outlined recovery procedure means you can act faster and more decisively to minimize downtime.

Effective OT security is built in, not added on

Much like IT, OT security works best if it is inherent to your systems, and not bolted on as an afterthought. Knowing the standards and understanding best practices helps to a degree, but if you want OT network security integrated into your overall security posture, call in the cybersecurity experts.