These findings come from Chinese researchers who were able to hack into users’ mobile phones and use the device’s accelerometer — the sensor used to track your phone’s tilt and motion — to pinpoint where they travelled on a Chinese subway system.
The underlying theory of the paper is that smartphone accelerometers can be used by hackers to create a blueprint of motion. That is, subway stations are connected by jerky tracks and no two subway station’s connections are the same. Thus these researchers were able to record and analyse the “motion patterns” of trains to learn which certain set of motions correlated to which station.
Every station has a unique fingerprint of motion, and if hackers learned to identify and recognise them they would be able to know where a person was just by analysing the way their mobile phone moved.
It may sound like it would take hackers a long time to learn the motion patterns for each station, but the researchers tracked people with over 85% accuracy and only collected data from “a few station intervals with obvious characteristics.”
This paper presents a method to track people in places that were before considered impossible: Underground, where there likely is no mobile phone reception.
Accelerometers are used in nearly every phone to give it the video game-like ability to respond to tilt and motion. But mounting research has indicated that it also can be used for all forms of surveillance.
Of course, to do this hackers would need to figure out a way to remotely access the accelerometer and access its data. The most likely way would be to have users unknowingly download a malicious app that would then tap into the phone’s sensor. When successfully done, it’s difficult to detect if someone has hacked into an accelerometer — although one can usually tell by a heightened battery drain.
This isn’t the first time this internal device component was used for surveillance. In 2010, for instance, a Japanese company built a program that claimed to track employees’ movements via their mobile phones’ accelerometers. This provided managers a way to know which users were goofing off, using the bathroom too often, talking to much at the water cooler, and generally wasting time.
Like this latest research, in that case the accelerometer was used in lieu of GPS and it was able to give employers shocking data about underling work patterns.
While a future of systematic accelerometer hacking may seem far off, the technology is advancing leaps and bounds. The subway tracking researchers write, “The results show that the inferring accuracy could read 89% and 92% if the user takes the metro for 4 and 6 stations, respectively.”
So it looks like screenwriters may soon have to re-think future scenes where spies are stymied by targets escaping via underground transport.
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