OT Patching
OT patching is one of the most misunderstood parts of industrial cybersecurity. In IT, patching is routine. In OT, patching is a risk-managed change. The systems you are updating often support physical processes, safety interlocks, and production continuity. A "simple update" can introduce downtime, break vendor support, or create behaviour that operators have never seen before.
At the same time, unpatched systems do not stay neutral. Over time, they collect exposure through known weaknesses, outdated components, and dependencies that were never designed for modern connectivity. OT patching exists to reduce that exposure without creating operational instability.
Arista Cyber helps organisations plan and execute OT Patching in a way that fits industrial reality. That means knowing what can be patched, what should not be touched yet, what must be tested first, and what compensating controls are needed when patching is not possible. The outcome is not "patch everything." The outcome is a safe, governed process where patching decisions are deliberate, documented, and repeatable.
PROTECT, RECOVER, AND SUSTAIN OPERATIONS OT RESILIENCE STARTS WITH BACKUP. SAFEGUARD YOUR OT SYSTEMS WITH BACKUPS YOU CAN TRUST AND RECOVERIES YOU CAN COUNT ON
Why OT Backup & Recovery Matters
OT recovery is different from IT recovery. In IT, restoring a server often means restoring data and access. In OT, restoring a system can affect control behaviour, process stability, and safety readiness. You may need to restore in a specific order. Vendor tools may be required. The environment may depend on older systems that cannot be rebuilt quickly.
A strong OT backup and recovery program answers practical questions:
- ✔ What must be backed up to restore operations, not just to "save files."
- ✔ How frequently backups should run and who owns them
- ✔ Where backups are stored and how they are protected
- ✔ How to restore safely without introducing configuration drift
- ✔ How to validate that backups are usable before an incident occurs
Key Advantages
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1.Reduce exposure without disrupting operations.
Patching is planned around uptime requirements, safety constraints, and vendor dependencies, so risk is reduced without reckless changes. -
2.Standardise patch decisions across sites and systems
A governed patch process prevents one-off decisions and inconsistent practices. This reduces drift and makes posture easier to manage over time. -
3.Improve audit readiness and security governance.
A documented patch program shows what is patched, what is deferred, why it is deferred, and how risk is managed in the meantime.
Deliverables
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✔ OT patching policy and governance
A practical patching policy for OT that defines ownership, approval paths, maintenance window expectations, and evidence requirements. -
✔ Asset patchability and dependency assessment
A clear view of what can be patched, what requires vendor involvement, what must be tested in staging, and what carries higher operational risk. -
✔ Patch prioritisation and rollout plan
A prioritised patch plan based on exposure and operational impact, with a rollout sequence that respects criticality and site constraints. -
✔ Testing and validation plan
A practical testing plan that shows how patches will be checked before they touch production, what "good" looks like for your environment, and who signs off before rollout. -
✔ Execution runbooks and rollback planning
Clear runbooks for patching high-impact OT systems, including the pre-checks to run, the order of steps, and a rollback path if something behaves differently after the update. -
✔ Patch status reporting and exception tracking
A straightforward view of what has been patched, what is still pending, what has been deferred, and how risk is being managed when a patch cannot be applied yet.
Our Approach
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1) Establish the patch baseline
First, we take stock of the environment as it actually exists today, not as it was documented years ago. We capture OS and firmware levels, vendor application versions, and the dependencies that can break if updates are handled carelessly. We also note where patching has been ad-hoc, where exceptions are already in place, and which systems need extra caution because uptime and safety come first.
The goal at this stage is clarity. Teams should not be guessing what is patchable or what is supported. -
2) Prioritise with OT context
OT patching cannot be driven by scores alone. We prioritise patches based on how systems are used, where exposure exists, and what the operational consequences could be if a weakness is exploited. In many environments, the right question is not "how severe is the vulnerability" but "what does this system control and how reachable is it?"
This approach helps avoid wasted effort and prevents patch programs from stalling under the weight of low-value work. -
3) Test safely before touching production
Testing is where OT patching either becomes reliable or becomes risky. We define how patches should be validated in a non-production setting whenever possible, and we align testing with vendor expectations and site engineering practices.
If a proper staging environment is not available, we plan alternatives that reduce risk, such as controlled rollouts, limited scope testing, and tighter rollback preparation. -
4) Execute in controlled windows
Patching is carried out in planned maintenance windows with clear approvals and pre-checks. Execution is structured around runbooks, so outcomes are repeatable and not dependent on one person's memory. Where vendor participation is required, access is governed and time-bound, and activity is tracked. -
5) Confirm outcomes and manage exceptions
After patching, we confirm system health and operational behaviour, not just installation success. We also maintain exception records for patches that are deferred, including the reason and the compensating controls used to manage risk in the interim. This keeps the program honest and prevents "temporary" deferrals from becoming permanent blind spots.
Highlights
- ✔ Patch planning that respects uptime and safety
- ✔ Clear exception handling when patching is delayed
- ✔ Testing, rollout, and rollback discipline
- ✔ Reporting that supports governance and audits
Ready to Improve OT Patching Control?
OT patching does not need to be chaotic, and it should not be avoided until a major incident forces action. With the right governance, testing discipline, and rollout planning, patching becomes a steady risk-reduction program that operations can support.
If you want to bring structure to OT patching and reduce exposure without disrupting production, Arista Cyber can help you design and run an OT patching program that works in real industrial conditions.
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