Patching is a critical line of defense in protecting OT assets from cyber threats. Simply put, patching involves updating software to fix bugs, enhance security, and/or improve functionality. With regular patching, organizations can reduce the likelihood of unauthorized access, malware infection, or other security incidents while also ensuring compliance with industry regulations.

OT networks, especially for manufacturers, utilities, and other critical infrastructure present additional challenges compared to many enterprise networks, and patching is not as straightforward. Because of the high stakes of downtime, system stability, and safety for many OT network devices, the risk tolerance for deploying patches is much lower. This means organizations cannot rely on standard IT practices like pushing updates during non-business hours for OT devices. Instead, patching must be a carefully planned and controlled process.

This blog outlines the challenges with patching OT systems and explores practical strategies for keeping your OT networks secure.

Understanding the Challenges of Patching OT Systems

Unlike IT systems that can often tolerate brief downtime, OT systems are designed to run continuously. Shutting down many OT systems for patching, even briefly, can disrupt production or trigger safety failsafes. Some additional challenges with performing OT patching commonly include:

• Legacy hardware or software that has labor intensive patching processes
• The risk of crashes that could halt production or create unsafe conditions
• OEM or vendor requirements for patch approval or installation to maintain warranty support
• Limited internal resources to manage complex patching across diverse systems

Additionally, like an IT system, OT systems often have vulnerabilities in multiple layers including the operating system, applications, and device-level firmware. Plus, some OT devices aren’t even visible to standard network scans, especially those on hidden networks or behind proprietary gateways, making it challenging to know what exactly needs patching in the first place.

Mitigating Risk when Patching OT Systems

One of the most effective strategies for mitigating risk when deploying patches to OT devices is to utilize a simulated development environment, or digital twin, of your systems to test patches before applying them to live systems. This allows for functional testing that can validate how the entire system will behave post patch long before a patch touches your production environment.

If you do not already have a digital twin in place, ACE can help you establish one. This type of digital environment provides long-term value beyond patch testing for functions such as testing control logic changes and system upgrades as well as training operators on realistic systems.

Another strategy to mitigate risk is to consider working with a systems integrator with deep domain expertise. This is because effective patching requires the involvement of someone who can effectively coordinate with operations and IT teams, interpret vendor guidance on approved updates, and troubleshoot unexpected post-implementation system behavior.

One example where we recently demonstrated why this combination of expertise is important occurred after applying a patch to a controller for a customer. Following the return of the systems to operations, a different controller for a compressor failed to start and operations feared the patch had broken something in the inter-controller communication. However, our team quickly determined that the system’s logic had closed an upstream valve when the outage was initiated, which was expected behavior, and that the operators were required to issue a manual open command when returning to operation. This kind of rapid diagnosis was possible because our experts understand how an entire control system functions, not just the software.

Working with ACE to Manage Your OT Network Patching Requirements

At ACE, we understand that patching isn’t just a security requirement, it’s a strategic activity that touches every layer of your control system. Our OT cybersecurity experts stay current with patch information from a wide range of control system software vendors so that we know exactly what will work, and what won’t.

We bring this knowledge to every engagement, helping customers avoid one-off research while streamlining OT patch management. We also help customers standardize and automate patching. Plus, our detailed post-implementation reporting ensures customers have a clear understanding of what was patched, what risks remain, and why.

To see how ACE can help you implement a resilient patching program that will keep your OT systems secure, stable, and running strong, contact one of our cybersecurity experts today.