AirHopper. Keylogging Disconnected Computers.

AirHopper demonstrates how textual and binary data can be ex-filtrated from physically an isolated computer to mobile phones at a distance of 1-7 meters, with effective bandwidth of 13 to 60 bps. Enough to steal a password. The technology works by using the FM radio receiver included in many mobile phones and can capture keystrokes by intercepting certain radio emissions from the monitor or display unit of the isolated computer. The video shows how its possible to pick up FM signals on a nearby smartphone and translate the FM signals into the typed text.

Here is the paper on it.

With appropriate software, compatible radio signals can be produced by a compromised computer, utilizing the electromagnetic radiation associated with the video display adapter. This combination, of a transmitter with a widely used mobile receiver, creates a potential covert channel that is not being monitored by ordinary security instrumentation. Thusly, this proof of concept proves that if an attacker can place malware into a target’s phone, they can gather data getting entered into disconnected machines. So even disconnected machines aren’t safe.