As if worrying about whether someone is tracking your smartphone via the GPS chip or triangulating your cell signals, Stanford researcher Hristo Bojinov has discovered the accelerometers in our devices give off unique “fingerprints” that can be used to identify and potentially track a device. The accelerometer is typically used by a device to determine which way a handset is being held so the user interface can adjust for portrait or landscape mode, although other apps make use of the data as well, especially gaming apps or fitness apps. Each accelerometer has to be calibrated so the device will be able to understand the data. Normally, very small deviations may be ignored by the operating system, but they are still being generated by the accelerometer if for no other reason than due to the effects of tiny defects in the manufacturing process and Mr. Bojinov discovered no two accelerometers are alike.
Using this data that is constantly generated, someone could produce a piece of Javascript that reads these values and store them in a database. Since each set of numbers is unique to a particular accelerometer, this could be used to identify and track a particular device. Mr. Bojinov demonstrates this with a web site he created at Sensor-ID.com. You can point your mobile browser there if so inclined to see what number your phone generates. In testing thus far, all devices have been generating their own unique numbers.
The uniqueness of the accelerometers is not the only identifiable bit of information about smartphones that Mr. Bojinov has discovered. He also determined every microphone generates a unique “soundprint” that could be used to identify a particular handset. Fortunately, tracking down a smartphone based on the microphone soundprint would be difficult to do as it would require user interaction which would likely tip them off to the tracking attempt. The accelerometer method is not limited in this way though.
Thus far it has not been determined whether any nefarious uses have been crafted using this data, but it is worrisome according to Dan Auerbach with the Electronic Frontier Foundation.
source: PhoneArena
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