New research has found information leaked by cell towers can be used to determine your cell phone’s general location.
The situation was detailed by researchers from the University of Minnesota, who discovered that there is enough information leaked from the lower layers of the GSM [Global System for Mobile Communications] communication stack to permit attackers to perform what they call “location tests” on targeted devices.
“Cell phone towers have to track cell phone subscribers to provide service efficiently,” University of Minnesota Phd student Denis Foo Kune, one of the authors of the paper, explained in a prepared statement. “For example, an incoming voice call requires the network to locate that device so it can allocate the appropriate resources to handle the call. Your cell phone network has to at least loosely track your phone within large regions in order to make it easy to find it.”
The cell tower will broadcast a page to a person’s phone and wait for the device to respond when a person gets a call, he continued. According to the researchers’ findings, it is possible for a hacker to force those messages to go out and hang up before the victim is able to hear their phone ring, ultimately enabling them to find a person’s general location within about a dozen city blocks.
“We focus on the common lower GSM stack layers at layers 2 and 3 and pay attention to the effects of the broadcast channels on the location privacy of users,” the researchers note in the paper. “We show that although GSM was designed to attempt to obfuscate the identity of the end device with temporary IDs, it is possible to map the phone number to its temporary ID. We also show that it is possible to determine if a user’s device (and by extension, the actual user) is within an area of 100 km2 with multiple towers by simply looking at the broadcast messages sent by the network.”
The researchers focused on the T-Mobile and AT&T GSM networks. The paper, which was presented earlier this month at the 19th Annual Network & Distributed System Security Symposium in San Diego, can be read here.