Implementing OT security best practices for industrial networks

Industrial systems cover everything from critical infrastructure through to factories and production lines. But no matter their task, these facilities all have one thing in common - the need for a robust OT security strategy.

Each relies on operational technology to control equipment, monitor conditions, and respond to potential threats in real-time. While these systems often work quietly in the background, they’re essential to the smooth running of operations.

The problem? Many of these systems weren’t designed with modern cyber security threats in mind. And as more organisations connect OT environments to their IT systems, the risk only increases. With devices exposed to the internet, threat actors can find new ways in, increasing the attack surface. OT security is all about protecting these environments from disruption.

In this guide, we’ll look at what makes OT security unique. We’ll also see the common challenges involved in day-to-day management. Finally, you’ll learn several steps you can take to implement OT security best practices across your industrial networks.

What is OT in cyber security?

Operational technology (OT) describes the devices and software that control physical systems, such as programmable logic controllers (PLCs), SCADA systems, and industrial control systems (ICS). These tools are often used with real-world machinery, which is why securing them is so important.

In cyber security terms, OT environments require a different approach to traditional IT. They often prioritise stability and uptime above all. However, many use outdated protocols, can’t be patched easily, and don’t support modern authentication or encryption.

When these devices are increasingly connected to corporate networks and the internet, that presents potential issues. Without proper protections, these gaps allow attackers in. And once inside, they can cause real damage - interrupting services, harming infrastructure, breaching data, even putting staff at risk.

Pat Rodgers, Managed Networks Product Manager at Nasstar, said: “Organisations should be taking a multi-layered approach to security, a firewall for the main office is not sufficient when you have cloud applications, remote users, and an increased OT landscape. Each touchpoint needs addressing, sometimes with different technologies and approaches.”

Why is OT cyber security important?

OT security is important because industrial networks are no longer isolated from other IT systems. Everything is connected. With predictive maintenance tools, connected sensors and cloud dashboards, OT systems now constantly share data with wider IT environments. This brings massive productivity and competitive benefits, but also new threats.

As we’ve seen in recent high-profile incidents like the Colonial Pipeline, attackers know that supply chain disruption can be more lucrative than data theft alone. Estimates show that downtime costs global companies a combined $400b per year.

That reason alone is why bad actors are targeting OT systems more and more. Downtime in sectors like energy and utilities or manufacturing can cause real-world issues that attackers can benefit from.

Leigh Walgate, Managing Director of Secure Networks at Nasstar, said: “It’s well known that digital transformation brings numerous benefits and efficiencies to MLEU organisations. However, what’s often overlooked are the potential cyber security risks and technological vulnerabilities that could impact a business. By combining Fortinet and Cisco’s advanced technologies with our expertise, we help build secure and adaptable networks that empower businesses to focus on what matters most - growth and innovation, knowing their systems are optimised and well-protected.”

For companies, securing OT environments helps prevent this kind of disruption. It protects people, processes and infrastructure, allowing organisations to keep modernising without putting critical systems at risk.

What are OT integration IT concerns?

So, what exactly are the major OT security concerns? Here are some of the most common.

Exposure of OT systems to internet-based threats

Many OT devices were never designed to go online. Once they’re connected without proper safeguards, these systems become easy targets. Encryption, firewalls and secure protocols all help keep them safe.

Lateral movement of malware between IT and OT networks

As we’ve seen, many types of systems are now interconnected. In theory, an attacker could get into a company through an email on the IT side - but that doesn’t mean they stop at just IT. Without protection, malware can jump from IT to OT, taking out control systems along the way.

Lack of shared visibility across IT and OT teams

You can’t fix a problem if you don’t know about it. If IT and OT teams work separately in silos, threats can slip through the cracks. Shared dashboards, joint alerting and common processes all help spot problems before they affect business.

Misconfigurations and legacy protocols

Many OT systems still rely on decades-old software. That’s a concern for IT security teams used to modern tools that are (mostly) internet-ready. Bridging that gap safely takes planning, testing and sometimes creativity.

Misaligned system updates

What looks like a simple update in the IT world can bring an entire production line to a halt in OT. That’s why patch management in OT needs to be careful, coordinated and well-tested before anything is deployed.

Policy enforcement across both environments

Security means consistency. But if OT and IT teams use different tools and processes, gaps can appear. A unified approach - with clear responsibilities and shared policies - is the only way to close them.

If you’re looking to improve your Industrial Internet of Things (IIoT) network security, here are some steps you can take.

Industrial OT security best practices step by step

Darren Hogan, Portfolio Director at Nasstar, said: “We always say to customers it’s better to be proactive than reactive. One of the best ways to be proactive is implementing zero trust network access, as this conditional access-based approach to users and data provides visibility, increases compliance, reduces risk and limits the blast radius in the wake of a breach.”

A typical OT security program will take the following steps as a minimum.

1. Asset inventory and risk assessment

First, you should gather all the information you can on your existing systems. Start with a full inventory of your OT devices, networks, and connections. Map everything from hardware and firmware to vendors and current software versions. That way, you’ll know what’s vulnerable and where you need to act as a priority.

2. Patch management and firmware updates

Unpatched IoT devices and legacy systems are a potential entrance point for many types of attacks. As such, one of the first things to do is to be proactive about your patching schedule. Test everything before rollout and prioritise based on risk and operational importance. If you can’t patch a system, you can at least isolate it and put security controls in place.

3. Access controls and least privilege

Next, it doesn’t matter the device or data - secure access to everything on a need-to-know basis. For this, you can use security tools to grant role-based access with regular reviews on who can get to what. This way, should a cyber attack get into your IT networks, the damage will be limited. Remember to remove any old or unused accounts and implement multi-factor authentication wherever possible.

4. Network segmentation

Similarly, you can lower your security risk by dividing your network into defined segments. This makes sure potential attackers can’t move freely across your entire system. Segment your OT network from IT systems using VLANs, firewalls, and DMZs. Then, you can also break OT assets and endpoints into further zones based on function or risk level. If something goes wrong in one area, these security measures mean you can at least contain it.

5. Take a zero-trust approach

The key to all IT and OT security solutions? Assume nothing while verifying everything and everyone. In practice, that means every device, user, and request should prove it belongs. Zero trust means tighter control, better visibility and fewer opportunities for bad actors to slip through the net, giving you strong mitigation should a device or password fall foul of a cyber threat.

6. Monitor systems and perform regular audits

As your digital transformation takes hold and security posture improves, you need to spot further opportunities. A good way is to use automation to monitor network traffic, with real-time alerts and Security Information and Event Management (SIEM) tools to spot potential security incidents. Combine that with regular audits to catch poor configurations and policy violations.

7. Develop and test an incident response plan

While many industrial OT security best practices are about prevention, you also need a cyber security framework for if an attack happens. Define roles, communication paths and response steps in advance. This will also help you forecast your information technology security, device lifecycles and ongoing risk management.

How Nasstar can help

The recent increase in industrial IoT devices has brought several huge opportunities for businesses. But it also brings new challenges. That’s because each business has its own cyber risks and vulnerabilities along with unique challenges. However, there are several key steps almost all companies can take to improve their security postures, including patching, zero-trust architecture, and monitoring.

Are you looking to optimise your industrial IoT security operations? Nasstar’s team of experts can help you identify risks, modernise systems and mitigate threats before they impact business continuity. Speak to a specialist to learn more.