OT Security
Practical, layered protection for the systems that run your site.
Operational Technology (OT) security has become a core part of modern SCADA and industrial engineering.
Not because sites are suddenly unsafe — but because today’s plants are more connected, more automated, and more interlinked with IT systems than ever before.
The challenge is simple: How do you protect critical systems without disrupting the processes they control? This page breaks down OT security in plain language and shows how we support organisations taking sensible, manageable steps to improve their resilience.
What Makes OT Security Different?
OT systems handle physical processes, not just data. That means the priorities flip compared to traditional IT security:
IT Priority
- Confidentiality first
- Patch quickly
- Replace outdated systems
- Tight user restrictions
OT Priority
- Availability first
- Patch carefully, avoid outages
- Maintain legacy systems safely
- Keep operators able to respond fast
Poor security can cause real-world disruption: downtime, damaged equipment, or unsafe conditions. But overly aggressive security can cause the exact same thing. So OT security needs a steady, engineering-led approach — not an IT-style “lock everything down” mindset.
The UK OT Security Landscape — The Simple Version
1. NCSC Guidance (UK’s National Cyber Security Centre)
The NCSC publishes practical advice specifically for OT. Their core message is:
- Know what you have (build an asset list).
- Understand how it connects.
- Segment the network so faults can’t spread.
- Use secure remote access only when needed.
- Plan for recovery, not just prevention.
This is the most realistic and engineering-friendly guidance available.
2. IEC 62443
IEC 62443 is the “gold standard” for OT cybersecurity design. It encourages:
- Separating networks into zones
- Defining security levels
- Controlling who/what can access each zone
- Securing components (PLCs, HMIs, remote access, sensors)
- Considering security from design → commissioning → operation → decommissioning
You don’t need full certification to benefit — simply following its principles makes your system significantly safer.
3. ISO/IEC 27001 (and ISO 27019 for energy/utility environments)
These set the management side of security: policies, documentation, risk assessments, user access control, incident response, supplier management. Organisations often combine ISO 27001 with IEC 62443: 27001 covers governance, 62443 covers the engineering.
4. NIS Regulations (for “essential services”)
If you operate in energy, water, transport, or other critical infrastructure, the NIS Regulations apply. They require appropriate security for OT, incident reporting, strong governance, and evidence of risk management. If you’re not an “operator of essential services,” NIS may not apply — but it still shapes best practice in industry.
What OT Security Looks Like in Practice
The straightforward, engineering-led version
1. Asset Inventory & Visibility
You can’t secure what you don’t know you have. We help you identify PLCs, HMIs, network switches, telemetry links, remote access points, software versions, and communication paths. This alone fixes many hidden risks.
2. Network Segmentation
Keep SCADA and control networks separate from corporate IT. Keep critical PLCs separate from non-critical areas. Use firewalls, VLANs, or simple routing rules to limit what can talk to what. Segmentation stops small problems becoming big ones.
3. Hardened Remote Access
Remote access is useful — but risky. We ensure MFA, logging, time-bound access, and vendor reach only to what they need, keeping OT isolated from the internet.
4. Secure Telemetry & Data Flows
Telemetry boundaries should be one-way wherever possible. Where two-way is required, it should be tightly controlled. We make sure telemetry paths don’t accidentally expose control systems.
5. Patch & Update Strategy (Done Safely)
You can’t patch OT systems like laptops. We test patches, plan maintenance windows, prioritise critical vulnerabilities, avoid changes during peak operations, and maintain rollback plans.
6. Operator Awareness
Most incidents start with an innocent action. We reinforce simple good habits, awareness of remote access risks, phishing aimed at OT/SCADA, and spotting unusual behaviour.
How SES Engineering Supports Your OT Security Journey
Practical steps, not overwhelming projects.
OT security doesn’t have to be complicated. We take a measured, engineering-friendly approach that fits naturally into your control and SCADA environment.
We help you by:
- Assessing your current setup. A quick review of your networks, devices, and access paths highlights easy wins.
- Prioritising improvements. Not all risks are equal. We focus on changes that deliver real protection without disrupting operations.
- Implementing practical, proven controls. Segmentation, secure remote access, logging, backups — simple measures used well are more effective than complex systems used poorly.
- Working collaboratively. We build solutions with your operators and engineers, ensuring security never comes at the cost of usability or uptime.
We’re here to help businesses take confident, sensible steps into a more secure OT future.
Where You Can Go From Here
If you’d like to explore how AI could support your site, you have two options:
Explore the other disciplines that keep your operations stable and predictable.
If you’d like a practical discussion about strengthening your OT environment, we’re happy to help — whether it’s a quick review or a specific project idea.