Computer speakers and headphones make passable microphones and can be used to receive data via ultrasound and send signals back, making the practice of air gapping sensitive computer systems less secure.

In an academic paper published on Friday through preprint service ArXiv, researchers from Israel’s Ben-Gurion University of the Negev describe a novel data exfiltration technique that allows the transmission and reception of data – in the form of inaudible ultrasonic sound waves – between two computers in the same room without microphones.

The paper, titled, “MOSQUITO: Covert Ultrasonic Transmissions between Two Air-Gapped Computers using Speaker-to-Speaker Communication,” was written by Mordechai Guri, Yosef Solwicz, Andrey Daidakulov and Yuval Elovici, who have developed a number other notable side-channel attack techniques.

These include: ODINI, a way to pass data between Faraday-caged computers using electrical fields; MAGNETO, a technique for passing data between air-gapped computers and smartphones via electrical fields; and FANSMITTER, a way to send acoustic data between air-gapped computers using fans.

Source: Air gapping PCs won’t stop data sharing thanks to sneaky speakers • The Register