AIR-GAPPED SYSTEMS, WHICH are isolated from the Internet and are not connected to other systems that are connected to the Internet, are used in situations that demand high security because they make siphoning data from them difficult.

Air-gapped systems are used in classified military networks, the payment networks that process credit and debit card transactions for retailers, and in industrial control systems that operate critical infrastructure. Even journalists use them to prevent intruders from remotely accessing sensitive data. To siphon data from an air-gapped system generally requires physical access to the machine, using removable media like a USB flash drive or a firewire cable to connect the air-gapped system directly to another computer.

But security researchers at Ben Gurion University in Israel have found a way to retrieve data from an air-gapped computer using only heat emissions and a computer’s built-in thermal sensors.

Read more at Wired.