Israeli security researchers have found a new technique to hack ultra-secure air-gapped computers and retrieve data using only heat emissions and a computer’s built-in thermal sensors. The new technique, dubbed BitWhisper, allows hackers to stealthily siphon passwords or security keys from a secured system and send the sensitive data to an Internet-connected system. The researchers demonstrated that the communication can also be bi-directional with both computers capable of transmitting or receiving commands and data by using the same heat and sensor technique.
Source: https://thehackernews.com/2015/03/hacking-air-gapped-computer.html