Earlier this week the Center for Democracy and Technology (CDT) warned that an Indian firm called SilverPush has technology that allows adverts to ping inaudible commands to smartphones and tablets.
Now someone has reverse-engineered the code and published it for everyone to check.
SilverPush’s software kit can be baked into apps, and is designed to pick up near-ultrasonic sounds embedded in, say, a TV, radio or web browser advert. These signals, in the range of 18kHz to 19.95kHz, are too high pitched for most humans to hear, but can be decoded by software.
An application that uses SilverPush’s code can pick up these messages from the phone or tablet’s builtin microphone, and be directed to send information such as the handheld’s IMEI number, location, operating system version, and potentially the identity of the owner, to the application’s backend servers.