Air-gapped SCADA systems: what operational gaps teams miss

TL;DR: So-called air-gapped SCADA environments are routinely undermined by USB media, vendor laptops, shadow bridges, supply-chain contamination and side-channel paths, according to Asimily, so the real control problem is continuous visibility into every device and connection, not the assumption of perfect isolation. Physical separation alone does not survive maintenance, remote troubleshooting and third-party access without governance over every crossing point.

Editorial analysis by NHI Mgmt Group, based on content published by Asimily: “Mind the Gap: Why Your “Air-Gapped” SCADA System Is a Myth”.

Key questions

Q: What breaks when an air-gapped SCADA environment relies on normal maintenance workflows?

A: The isolation claim breaks when routine maintenance depends on removable media, vendor laptops or bridged connections that are not governed as privileged access paths.

Q: Why do removable media and vendor devices create such a high-risk OT exposure?

A: They create high risk because they bring outside trust into a control environment that was designed to assume very limited change.

Q: What are the signs that an air gap is failing in practice?

A: Look for dual-homed workstations, unexplained modem links, ad hoc vendor access, inconsistent device baselines and traffic that does not match the approved protocol profile.

Practitioner guidance

• Inventory every crossing point into the OT boundary Map USB handling, vendor laptops, remote maintenance links, dual-homed workstations and cellular modems as explicit ingress paths, then assign an owner to each one.
• Restrict removable media to approved transfer workflows Require scanning, validation and documented approval before any firmware, logic file or log export is introduced into a control environment.
• Baseline every device before trusting it on the segment Capture known-good device behavior, protocol use and configuration state so deviations from expected OT activity surface quickly during operations.

Bottom line: Air-gapped SCADA fails most often through routine operational exceptions, not through headline remote exploits.

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