Resilience and Defense in Depth

An air-gapped system is one that is physically isolated from other networks, particularly the internet, with no direct network connection at all, on the theory that a system nothing can reach over a network cannot be compromised remotely. Air gaps are common in environments with especially severe consequences for compromise, such as industrial control systems managing physical infrastructure, certain classified government systems, and some critical safety systems. The tradeoff is substantial: an air-gapped system is far harder to patch, monitor, and manage, since routine tasks that assume network connectivity — pushing a software update, forwarding logs to a central monitoring platform — become manual, cumbersome, and easy to neglect on an isolated system that no one is looking at day to day. An air gap also is not an absolute guarantee of safety, since data still has to move on and off such a system somehow, typically via removable media, and that transfer point becomes the new focus of risk — a well-known historical case involved malware reaching an air-gapped industrial facility precisely through removable media carried in by an infected device, illustrating that physical isolation shifts risk rather than eliminating it outright.