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Ars Technica: An air gap is a security measure that isolates computers and networks to avoid the possibility of infection by malware via internet connections. However, Michael Hanspach of the Fraunhofer Institute for Communication, Information Processing, and Ergonomics in Germany and his colleagues have developed a proof-of-concept project to show that computers can also transmit information covertly using built-in microphone and speaker systems. Using two laptops placed almost 20 m apart, they were able to transmit information using audio frequencies outside the range of human hearing. While the transmission rate was quite slow—just 20 bits per second—it was enough to transmit live keystrokes or recorded passwords. And if a network of computers were infected, the system could serve as a signal repeater to transfer the information even farther. The options for countering a potential infection include manually disabling audio hardware or putting into place a high-frequency audio jammer that would disrupt the transmission signal.
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Scientists develop malware that transmits data via audio signals Free
3 December 2013