Imagine telling a plant operator to “just update the system” in the middle of a production run. You’d likely get a look of disbelief – and for good reason. Patching operational technology (OT) systems (the control systems running factories, power plants, pipelines, etc.) is a completely different beast from patching office IT gear.
In this third installment of our industrial cybersecurity series (after “Why Hackers Love OT Legacy Systems” and “The Dangerous Myth of the Air Gap”), we’re tackling why applying patches in OT environments is so challenging and how it introduces unique risks for industrial control system (ICS) operators.
Why Patching Industrial Systems Is So Risky
In the IT world, patching is often routine – updates get applied overnight, and the worst outcome might be a crashed application or a reboot. But in OT, a bad patch can have real-world consequences. As one OT engineer put it, “If I push this patch, what’s going to happen to the industrial process?”. Industrial systems are directly tied to physical equipment and processes – in other words, “1’s and 0’s could be the difference between a safe shutdown and an explosion,” as one industry report noted. This isn’t just hyperbole.
Even a brief downtime or malfunction in an ICS environment can cascade into serious safety, operational, or financial consequences. In sectors like manufacturing, energy, or transportation, stopping a system at the wrong time might halt production lines, cause equipment damage, or even put lives at risk.
The stakes are clearly higher in OT/ICS. That’s why patching decisions in industrial networks must be made very carefully. Unpatched vulnerabilities do pose security risks – but applying updates without proper planning could introduce instability to critical controllers or sensors. In other words, a security patch meant to fix a software flaw might accidentally upset the finely-tuned balance of a physical process.
No ICS operator wants to trade a cyber risk for a process upset. Thus, many organizations end up delaying or avoiding certain patches, trying to balance security with keeping the plant running safely.
Industrial operations often prioritize safety and uptime above all. Patching an OT system without due caution can disrupt that careful balance, which is why operators approach updates with a healthy dose of fear and respect. In an environment where people literally wear hard hats, changes to control systems are never taken lightly.
The Maintenance Window Dilemma
Another major difference between IT and OT patching is when updates can be applied. In enterprise IT, you might install updates any evening or over a weekend with minimal fuss. In industrial settings, however, you typically only get to touch critical systems during scheduled maintenance windows – and those might be infrequent and very short.
Many OT systems run 24/7 by necessity, so any downtime for patching has to be carefully slotted in to avoid interrupting production. Shutting down a factory line or a power turbine for an update is a big deal; even a short outage can mean lost product, missed deadlines, or safety hazards.
Because of this, patching in OT is usually postponed until a planned outage – say an overnight maintenance period, a holiday shutdown, or the rare quarterly (or annual!) maintenance day. And when that window arrives, there’s no guarantee the patch will be applied; it first has to pass thorough testing in a lab or staging environment. Unlike the plug-and-play updates of IT, every OT patch must be treated with suspicion until proven compatible.
Operators will test patches on offline systems or simulators extensively to ensure they don’t introduce new issues. Is this patch even compatible with our mix of hardware and software? Will it play nicely with a decades-old PLC or HMI application? These questions have to be answered before any update touches the live system.
Even once a patch is vetted, rolling it out is a delicate operation. Often, patches require system reboots or taking devices offline momentarily – something many control systems haven’t done in years. Think about an HMI server or controller that’s been running continuously without a reboot; applying updates to it isn’t as simple as clicking “Restart”. The team needs to know exactly how long the reboot and patch process will take and ensure that fits into the allotted downtime.
As one OT security specialist notes, “patching isn’t as simple as applying it whenever needed – it must be coordinated with downtime schedules. Many patches require a reboot on systems that may not have been rebooted in years”. In short, OT patching can feel like a high-stakes race against the clock: you only have a tiny window to get it done, and failure to hit that window means waiting weeks or months until the next one.
Legacy Systems: The Unpredictable Patch Factor
On top of timing challenges, legacy systems make patching a nightmare of its own. Industrial sites are full of aging equipment and outdated software that still run critical processes. We covered in our earlier post why hackers love these legacy OT systems – they’re old, fragile, and often lack modern security.
Here’s another issue: they also often lack vendor support or clear upgrade paths for patches. A substantial portion of OT environments run on technologies so old that the manufacturers no longer release updates, or the systems are incompatible with modern patches. You might have a Windows XP-based HMI or a PLC from 1995 – obviously, you can’t just install the latest Windows update or firmware patch on these and assume all will be well.
For many veteran operators, the rule with legacy systems has been “If it isn’t broken, don’t fix it.” These systems have been chugging along for decades, and any change could upset their delicate equilibrium.
The result is a culture of caution: you only patch if you absolutely must, and even then with white-knuckled care. Why? Because with an older system, it’s often unclear what a patch might break. Perhaps an update conflicts with a custom driver, or a security patch causes a ten-year-old SCADA software to stop communicating. As our speaker emphasized, when dealing with legacy OT, you have to ask yourself “What is this patch actually going to break?”.
It’s genuinely hard to predict. A patch that works fine in the lab might have unforeseen side effects in the field – and since these legacy devices weren’t designed with modern cybersecurity in mind, troubleshooting them can be painfully slow.
Legacy systems also tend to be unpatchable or unsupported by nature. The original vendor might be out of business, or no longer issuing fixes for that old product line. In such cases, even if you want to patch, you might not have a good patch available – or you risk voiding support agreements by installing unofficial updates.
All of this means that industrial cybersecurity often has to rely on compensating controls (like network segmentation, strict access rules, etc.) to protect legacy equipment, because you can’t simply “fix” their vulnerabilities with a patch. It’s a tough spot: aging systems keep the plant running, but also handcuff your security efforts.
Conclusion: Facing the Patching Nightmare Together
Patching in OT environments may always be a bit of a nightmare – a delicate dance between fixing cybersecurity holes and not breaking the operational technology that keeps your world running. We’ve seen how operational risk, tight scheduling, and old equipment all conspire to make a task that’s routine in IT incredibly challenging in industrial settings. The good news is that you don’t have to face this challenge alone. Modern OT security practices and tools are emerging to help manage the patching puzzle, from better network visibility to virtual patching techniques, so that even legacy-laden plants can stay protected without constant downtime.
If your team is struggling with patching and worried about disrupting operations, it’s time to take action. Consider reaching out for expert help – this is exactly what we do at Insane Cyber. Our team understands how fragile OT systems can be, and we’ve built our solutions to minimize risk during things like patch management. Don’t let patching fears keep you up at night. Schedule a demo of our Valkyrie software platform to see how we can help you gain visibility and control in your OT environment, or simply contact Insane Cyber to talk with an expert about managing patches and improving your operational cybersecurity. We’re here to help you keep your plant running safely and securely – so you can finally put the OT patching nightmare to rest.
(This article is part 3 of our series on industrial cybersecurity. Be sure to check out the previous installments, “Why Hackers Love OT Legacy Systems” and “The Dangerous Myth of the Air Gap,” for more insights.)
