If you run a manufacturing facility, you already know that downtime is the enemy. Every minute a line sits idle costs money — sometimes a lot of it. That reality makes patch management one of the most uncomfortable conversations in industrial IT, because patching means updates, updates mean reboots, and reboots mean potential downtime. So a lot of manufacturers simply don’t patch. They push it off, tell themselves the equipment is air-gapped, and hope for the best.
That’s a bet that’s getting harder and harder to win.
Modern manufacturing environments run two distinct technology stacks side by side: traditional IT (desktops, servers, Microsoft 365, firewalls) and operational technology — the PLCs, HMIs, SCADA systems, and industrial controllers that keep machines running. Both stacks have vulnerabilities. Both need patches. And the stakes for getting it wrong are completely different in each one.
This guide walks through a practical, risk-aware approach to patch management that NWA manufacturers can actually implement — without scheduling a weekend of unplanned outages every time Microsoft drops a security update.
Why OT and IT Patching Are Fundamentally Different
Before diving into strategy, it helps to understand why you can’t just apply the same patch management process to both environments.
IT systems — workstations, servers, firewalls, switches — are designed to be updated regularly. Vendors ship patches on predictable schedules (Patch Tuesday, anyone?), downtime windows are short, and rollbacks are usually possible if something goes wrong.
OT systems are a different world:
- PLCs and HMIs often run firmware that hasn’t been updated in years — sometimes decades
- Many industrial control systems run end-of-life operating systems (Windows XP, Windows 7) that vendors no longer support
- Patches for OT equipment often require vendor certification before they’re safe to apply to production equipment
- A botched firmware update on a CNC machine or a process controller doesn’t just mean a help desk ticket — it can mean hours of lost production or a failed safety system
The risk profile is asymmetric. In IT, the risk of not patching is usually higher than the risk of patching. In OT, the equation is often reversed — at least in the short term.
The Core Principle: Risk-Tiered Patching
The most effective patch management strategy for a combined OT/IT environment isn’t “patch everything as fast as possible.” It’s risk-tiered patching — a structured approach that matches patch urgency to asset criticality and exposure.
Here’s how to think about it:
Tier 1 — Internet-Facing and High-Risk IT Assets
These get patched fast. We’re talking:
- Firewalls and edge routers
- VPN concentrators
- Remote access systems
- Public-facing web servers or portals
- Email gateways
Critical and high-severity CVEs on these assets should be patched within 24–72 hours of release. These are the systems attackers probe first, and delays here create real exposure.
Tier 2 — Internal IT Infrastructure
Servers, domain controllers, backup systems, workstations. Standard Patch Tuesday cycles work fine here — aim to have critical patches deployed within 7–14 days and all patches completed within 30 days.
Tier 3 — OT-Adjacent IT (DMZ/Engineering Systems)
Historian servers, engineering workstations, data diodes — systems that touch both the plant floor and the corporate network. These need careful testing before deployment. Plan for 30–60 day cycles with a formal change control process.
Tier 4 — Pure OT Assets (PLCs, HMIs, SCADA)
These follow vendor-led maintenance windows, often quarterly or annually. Do not apply patches to production OT without:
- Reviewing the patch notes from the OEM
- Testing on a spare/staging unit first (if available)
- A documented rollback plan
- Change control sign-off from operations
Building a Practical Patch Management Process
Strategy is only useful if it’s actually executed. Here’s what a working patch management process looks like for a small-to-mid-size NWA manufacturer.
1. Build Your Asset Inventory First
You cannot patch what you don’t know exists. This sounds obvious, but most manufacturers we work with in the NWA region have significant gaps in their asset inventories — especially on the OT side, where equipment may have been installed years ago without being logged anywhere.
Start with a network scan of your IT environment and a manual walk-through of the plant floor. Document every device: make, model, OS version, firmware version, and who owns it operationally.
2. Subscribe to Vendor Advisories
For every major vendor in your stack — Microsoft, Cisco, Rockwell Automation, Siemens, Schneider Electric, etc. — subscribe to their security advisory feeds. CISA (the Cybersecurity and Infrastructure Security Agency) also publishes ICS-CERT advisories specifically for industrial control systems and is a must-follow for any OT environment.
3. Establish a Change Control Process for OT
IT patches can often be deployed with minimal ceremony. OT patches cannot. Any firmware or software change to a production OT asset should go through a formal change control process that includes:
- Description of the change and reason (CVE number, performance issue, etc.)
- Risk assessment (what breaks if this goes wrong?)
- Test plan (did you test it on a non-production system?)
- Rollback plan (how do you get back to the previous state?)
- Maintenance window (when will production be down, and who’s been notified?)
- Sign-off from both IT and operations leadership
This isn’t bureaucracy for its own sake — it’s the minimum discipline needed to avoid turning a routine security update into a 12-hour production outage.
4. Use Compensating Controls Where Patching Isn’t Possible
For systems that genuinely can’t be patched — end-of-life Windows systems running legacy SCADA software, for example — compensating controls become essential:
| Compensating Control | What It Does |
|---|---|
| Network segmentation | Isolates vulnerable assets so attackers can’t reach them easily |
| Application whitelisting | Blocks unauthorized code from running on unpatched machines |
| Strict firewall rules | Limits inbound/outbound traffic to only what’s required |
| Enhanced monitoring | Detects anomalous behavior on systems that can’t be hardened |
| Privileged access controls | Limits who can log into or modify sensitive OT systems |
None of these is a substitute for patching. But they meaningfully reduce risk when patching isn’t an option.
5. Document Your Exceptions
Every system that’s running out-of-date software for a documented business or technical reason should be logged as a formal exception. Include:
- The asset
- The vulnerability or missing patch
- Why patching isn’t currently possible
- The compensating controls in place
- A target remediation date (even if it’s 18 months out)
This documentation is critical for compliance purposes — particularly if you’re pursuing CMMC or working toward other security certifications — and it forces the organization to consciously accept the risk rather than just ignoring it.
Common Mistakes NWA Manufacturers Make With Patching
Treating all patches as equally urgent. Not every patch is a fire drill. Focus your energy on vulnerabilities that are actively being exploited in the wild or that have a CVSS score above 7.
Skipping testing because “it’s just a security patch.” Security patches can and do break things, especially in industrial environments. Always test before deploying to production OT assets.
Relying on air-gap mythology. Many manufacturers believe their OT environment is completely isolated from the internet and therefore doesn’t need patching. In reality, most OT networks have more connectivity than their owners realize — through remote support connections, USB drives, historian servers, or poorly segmented corporate networks. Air-gaps are rarely as complete as assumed.
No rollback plan. If you can’t answer the question “how do we undo this if it breaks something?” before you apply a patch, you’re not ready to apply it.
Patching without notifying operations. IT and operations need to coordinate. A patch that requires a 20-minute reboot on the historian server during a production run can cause more disruption than the vulnerability it’s fixing.
What Good Patch Management Actually Looks Like
For most small-to-mid-size manufacturers in Northwest Arkansas, a realistic, sustainable patch management program looks like this:
- Monthly IT patching cycle aligned with Patch Tuesday, with a defined test-and-deploy window
- Quarterly OT review in coordination with equipment vendors and operations leadership
- Annual full audit of all assets against current patch levels, with exception documentation updated
- Emergency patch procedures for critical vulnerabilities (CVSS 9+) that require faster response
It doesn’t have to be complicated. It just has to be consistent.
Getting Started
If your organization doesn’t have a documented patch management process today, the first step is the asset inventory. You can’t build a strategy around assets you haven’t cataloged. Once you know what you have, the risk-tiered approach above gives you a practical framework to work from.
The goal isn’t perfect patch currency across every system — that’s often not achievable in a real manufacturing environment. The goal is to reduce your attack surface systematically, document your known risks, and make sure the most critical vulnerabilities are addressed before someone else finds them for you.
Ready to get your OT/IT patch management under control? Get in touch.