Navigating the OT Patch Management Dilemma

In industrial environment, Operational Technology (OT) is the backbone that keeps physical processes running smoothly. It systems usually consists of Programmable Logic Controllers (PLCs), Supervisory Control and Data Acquisition (SCADA), and Distributed Control Systems (DCS) that are tasked to control machinery, operations and processes in sectors such as energy, manufacturing, and utilities, etc. OT is all about real-time control, safety, and keeping the physical world in motion.

Patch management in OT environments, where computers are not rebooted for months or sometimes years, is not easy because of the risk of disrupting plant operations. Unlike traditional IT, patch management in OT is more complex due to the need to prioritize system availability.

In this article, we will explore patch management and patch installation in OT environments, along with the associated challenges.

In ACET Solution’s OT Cybersecurity webinar series, Mubarik Mustafa (Principal Consultant for OT/ICS cybersecurity) provided exclusive insight on patch management in the OT environment and how ICS and OT professionals can navigate between security and operational continuity.

“There are no perfect choices—only risk-based decisions.” Mubarik

Watch the full episode here.

Patch Installation vs Patch Management

Patch installation is the act of applying a software or firmware update to a specific device or system. It’s a single step within a much broader process.

Patch management, on the other hand, is a comprehensive process that includes identifying relevant patches, assessing risks, testing in a controlled environment, validating vendor compatibility, scheduling deployments during approved maintenance windows, and documenting changes for compliance.

In OT, these processes are far more complex than in IT, as they involve balancing cybersecurity needs with operational safety, regulatory compliance, and system uptime. Therefore, installing patches without a structured management or plan can destabilize critical infrastructure and, in the worst case, cause downtime.

Why Patching in OT is Non-Negotiable

Patch management in OT is focused on reducing cyber risk. Vendors release patches to address known security vulnerabilities, closing critical gaps that could otherwise be exploited. Unlike IT environments, OT systems, from refineries to power plants, are highly distributed, segmented, and often run specialized software. This creates a complex landscape for patch deployment where safety, high availability, and operational integrity cannot be compromised.

OT Patching Minefield: Understanding the Unique Challenges

• Availability is Priority: In OT, uninterrupted availability is king. Restarting a server or workstation is rarely an option, and the risk of downtime during patch installation is a constant and huge concern.
• Legacy systems: Till today, many critical OT systems are operating on older platforms like Windows NT or Windows XP, for which patches are unavailable, and in case they exist, they are incredibly difficult to install.
• Fragmented networks: While OT networks are often segmented or air-gapped, this isolation complicates centralized patch deployment and thus requires creative workarounds. Additionally, many organizations do not use central patch management or deployment solutions.
• OEM compatibility: A crucial, often painful step, involves securing approval from Industrial Control System (ICS) Original Equipment Manufacturers (OEMs). Often, these OEMs explicitly recommend that Microsoft updates are only applied after “full qualification” to prevent malfunctions in their proprietary software.
• Time and resource intensive: The process—from OEM approval to verification—can take months in large facilities.

In these contexts, applying conventional IT patch management without considering OT specific constraints can introduce significant risk, potentially leading to system instability or significant operational disruption.

Challenges of Patch Installation vs Management in OT

In the OT setting, patches aren’t applied for convenience or new features, they’re implemented to minimize security vulnerabilities, to reduce operational and cybersecurity risk while maintaining system stability. Each patch deployment is an intentional and risk-based decision, not just a routine update.

Patch management is about creating a system to have full visibility on which patches are installed, where they reside, and why. It involves making informed decisions about which patches should be deployed, when they can be safely applied, and where they will have the least operational impact.