GSM cellular networks leak enough location data to give third-parties secret access to cellphone users' whereabouts, according to new University of Minnesota research.
"We have shown that there is enough information leaking from the lower layers of the GSM communication stack to enable an attacker to perform location tests on a victim's device. We have shown that those tests can be performed silently without a user being aware by aborting PSTN calls before they complete," write the authors, from the College of Science and Engineering, in a paper titled "Location Leaks on the GSM Air Interface."
Publication of the paper, presented at the 19th Annual Network & Distributed System Security Symposium in San Diego, comes at a time when carriers, phone makers and software companies are under almost constant fire regarding customer privacy. Reports surfaced Friday that Google and others allegedly put code on iPhones that let companies track users' activities without them knowing, Apple itself vowed earlier this week to purge apps from the App Store that sneakily grabbed users' contact lists, and a software maker named Carrier IQ was at the center of a controversy in recent months regarding whether carriers used its technology to track users in nefarious ways.
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The computer scientists explain that wireless service providers' cell towers have to track subscribers to find the past path on their network and connect calls. The towers issue pages to phones to find them. (Access to device tracking information also needs to be made available for law enforcement reasons.)
The researchers demonstrated how easy it was to track down a cellular device within a 10-block area in Minneapolis using a T-Mobile G1 smartphone and open source technology. They never contacted the service provider to conduct the test.
"It has a low entry barrier," researcher Denis Foo Kune said, in a statement. "Being attainable through open source projects running on commodity software."
The concern is that agents from oppressive regimes could use such location data to track down dissidents or that thieves could watch a potential victim's phone exit an area and leave their home open for a break-in.
The researchers have contacted carriers and phone equipment companies (they specifically mention AT&T and Nokia in the paper) with ideas on how to safeguard location tracking data through GSM software stack upgrades and are working on responsible disclosure statements for service providers.
The research was funded in part by the National Science Foundation and Korean Advanced Institute of Science and Technology.
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