What are the best practices for Securing Industrial Control Systems (ICS/SCADA)?
I’ve recently moved into a security role at a manufacturing plant. Many of our PLC (Programmable Logic Controllers) are a decade old and can’t be patched. How do I balance the need for uptime with the critical need to secure these "legacy" devices from ransomware? Is network cloaking or air-gapping still a viable strategy in the age of IIoT?
2025-11-20 in Cyber Security by Lisa Ray
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All answers to this question.
Air-gapping is rarely a reality today because of the need for data analytics in the cloud (IIoT). Instead, follow the "Purdue Model" for network segmentation. Isolate the OT (Operational Technology) network from the IT network using an Industrial Demilitarized Zone (IDMZ). For unpatchable PLCs, use "Virtual Patching" via an Industrial Firewall or an IPS (Intrusion Prevention System) that can detect and block exploits at the network level before they reach the device. Additionally, implement passive monitoring tools like Dragos or Claroty that can identify anomalies in industrial protocols (like Modbus or DNP3) without disrupting the sensitive real-time traffic.
Answered 2025-11-22 by Margaret White
Are you managing your "removable media" risk? Most ICS infections come from an infected USB drive used by a technician rather than a direct internet connection.
Answered 2025-11-24 by Steven Wright
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Steven, you hit the nail on the head. The "Stuxnet" style of entry is still the biggest threat to OT. We’ve implemented "Sheep Dip" stations—dedicated, isolated computers that scan and clean any USB drive before it’s allowed near the production floor. Furthermore, we’ve disabled physical ports on most controllers. If a technician needs to update a PLC, they must use a "Clean Room" laptop that never leaves the site and is subject to rigorous daily audits. This human-centric control is often more important than the most expensive firewall in a factory setting.
Commented 2025-11-25 by Paul Robinson
Don't forget physical security. A locked cabinet and restricted badge access to the server room are just as important as your firewall rules in an industrial setting.
Answered 2025-11-26 by Karen Scott
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Karen's right. In manufacturing, the "threat actor" could just be someone plugging a laptop into an open Ethernet port on the factory floor. Physical security is the first line of defense.
Commented 2025-11-27 by Lisa Ray
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