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Apps can secretly track an Android phone’s whereabouts and traffic patterns without needing access to GPS or WiFi, researchers have found.
Researchers from Northeastern University in the US found that instead of using those features, you could do similar tracking by using a phone’s sensors, most of which don’t require permissions to use.
Such sensors include the accelerometer and pedometer, which detect movement and measures the number of steps taken by the user.
In the case of Android, apps that require access to a phone’s sensors don’t need to request permission to access – you can control permissions if you’re running the latest version, but only 15% of Android devices have Marshmallow.
When used together, the researchers say they can help figure out the route you take to work or whether you carry your phone in your pocket or bag.
To do this, they used an algorithm that inserted data from the phone’s built-in sensors into graphs of the world’s roads. The researchers applied it to various simulated and real-world roadtrips where they collected scores of measurements taken from the phone’s changing position, including the angle of turns and the trajectory of curves.
They did this by carrying out two types of tests. They simulated drives in 11 cities around the world including Berlin, London, Rome, Boston, and Atlanta. They also drove more than 1,000 kilometres over more than 70 different routes in the US, specifically Boston and Waltham, Massachusetts.
For each trip, it generated the five most likely paths taken with a 50% chance that the actual path traveled was one of the five.
“Our research shows than an Android app does not need your GPS or WiFi to track you,” said the lead researcher Guevara Noubir. “Just using its sensors, we can infer where you live, where you have been, [and] where you are going.”
Following these findings, Noubir plans to examine how much this tracking is actually happening to Android users in the real-world.