Android Apps Spy On Users By Hearing Inaudible Sounds Via Beacons

Android Apps Spy On Users By Hearing Inaudible Sounds Via Beacons
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It is already known that many Android apps track users without their knowledge, but now researchers have found that hundreds of applications could be tracking users covertly via inaudible sounds emitted by nearby devices. Researchers claim that such a technique can even be used to de-anonymize Tor and Bitcoin users.

Beacons help advertisers track your location

A team from the German Technical University of Braunschweig (Brunswick), found over 234 Android applications containing code called SilverPush, which listens for ultrasonic signals emitted by beacons or embedded in media. In April 2015, the researchers found that only six apps were using ultrasound cross-device tracking technology.

In recent years, companies have been hiding beacons in their ads to track users’ devices and learn more about them, notes the Independent. Beacons are ultrasonic audio signals that are inaudible to humans. Companies embed these beacons in the ultrasonic frequency range between 18 and 20 kHz of audio and detect them with regular mobile apps using the microphone of the device.

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