Researchers track smartphones using battery data

Chuck Bednar for redOrbit.com – @BednarChuck

Even if you don’t activate your smartphone’s GPS system or geotag your photographs, your mobile device can still be tracked based on the amount of power it uses over an extended period of time, a team of Stanford University researchers have revealed.

Stanford computer scientists Yan Michalevsky, Dan Boneh and Aaron Schulman, along with Gabi Nakibly from the National Research and Simulation Center at Rafael Ltd., explained in a new paper how they could track the location of a Nexus 4 smartphone running Android without accessing the device’s GPS hardware.

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What they did, according to ExtremeTech, was access the phone’s battery levels. The researchers relied on the assumption that a device uses more power to maintain a connection when the signal is obstructed or the phone is far away from a cell tower. Using that data, they developed a proof-of-concept location-tracking app called PowerSpy.

Obviously, it spies on your power

While they used a Nexus 4, the team said that the app would work on any mobile device that can access networks and track battery usage—or most modern smartphones. The app first records energy usage fluctuations throughout a route, and then creates an internal map of the area.

It uses this map to link power usage levels with certain locations, in much the same way that global positioning systems use satellites, they explained.

“The malicious app has neither permission to access the GPS nor other location providers (e.g. cellular or Wi-Fi network),” the researchers wrote, according to BBC News. “We only assume permission for network connectivity and access to the power data. These are very common permissions for an application, and are unlikely to raise suspicion on the part of the victim.”

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They mapped out several different routes between two points to determine which route the device was taking based solely on the battery usage. PowerSpy could pinpoint the precise route two-thirds of the time with an average distance error of 150 meters, according to ExtremeTech.

The app’s accuracy drops when the phone is in use and other sources “muddle” the power drain data. With many apps running in the background, the accuracy rate fell to just 20 percent with an average distance error of 400 meters, the website added.

Realities of modern life

“With mobile devices now becoming ubiquitous, it is troubling that we are seeing so many ways in which they can be used to track us,” Surrey University professor and cybersecurity expert Alan Woodward told the BBC News. “I think people sometimes forget that smartphones are stuffed full of sensors from gyroscopes and GPS to the more obvious microphones and cameras.”

“This latest work shows that even that basic characteristics (power consumption) has the potential to invade privacy if monitored in the right way,” he added. “We are approaching the point where the only safe way to use your phone is to pull the battery out – and not all phones let you do that.”

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Source: http://www.redorbit.com/news/technology/1113340046/researchers-track-smartphones-using-battery-data-022415/