In an article published online on August 15, Andy Greenberg reports that spies can take control of a smartphone and use it to record sound completely without the consent or cognizance of the user. Greenberg writes:
In a presentation at the Usenix security conference next week, researchers from Stanford University and Israel's defence [sic] research group Rafael plan to present a technique for using a smartphone to surreptitiously eavesdrop on conversations in a room — not with a gadget's microphone, but with its gyroscopes, the sensors designed to measure the phone's orientation. Those sensors enable everything from motion-based games like DoodleJump to cameras' image stabilisation [sic] to the phones' displays toggling between vertical and horizontal orientations. But with a piece of software the researchers built called Gyrophone, they found that the gyroscopes were also sensitive enough to allow them to pick up some sound waves, turning them into crude microphones. And unlike the actual mics built into phones, there's no way for users of the Android phones they tested to deny an app or website access to those sensors' data.
Scientists working with the Israeli military have developed a way to turn the phone’s gyroscope into a makeshift microphone sensitive enough to record ambient conversations.
Although certainly very clever, the hack isn’t perfect yet. Greenberg reports that the gyroscope-turned-microphone “could identify as many as 65 percent of digits spoken in the same room as the device by a single speaker” and “could also identify the speaker's gender with as much as 84 percent certainty.”
That level of accuracy is unsuitable for complex covert eavesdropping, but it demonstrates the potential of the procedure.
Citing information provided by Dan Boneh, a Stanford University computer security professor, Greenberg reports:
But Boneh argues that more work on speech recognition algorithms could refine the technique into a far more real eavesdropping threat. And he says that a demonstration of even a small amount of audio pickup through the phones' gyroscopes should serve as a warning to Google to change how easily rogue Android apps could exploit the sensors' audio sensitivity.
Although the experiment has been conducted so far only on phones running Google’s Android mobile operating system, similar devices manufactured by Apple use gyroscopes for a variety of functions, as well, and are thus susceptible to the surreptitious recording of sounds.
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