If you are already nervous about computer attacks, here’s some unwelcome news: there are many ways in which our technology is vulnerable based on physics, rather than on software. At the American Association for the Advancement of Science conference in mid-February, U-M computer scientist Kevin Fu and his colleagues reported a scary find: your computer hard drive could—without you knowing it—be used to record your voice.
Fu’s team turned a hard drive into a microphone by tapping into the feedback system that helps control the position of the read head above the magnetic disk. When the head is buffeted by sound waves, the vibrations are reflected in the voltage signal produced by the drive’s position sensors. By reading this signal, Fu and his colleagues were able to make high-quality recordings of people speaking near the drive. Software could use this technique to record audio and then secretly upload it, thus bugging a room without ever planting a microphone.