[LINK] Hacker Access to Mobile-Device Location

Roger Clarke Roger.Clarke at xamax.com.au
Fri Feb 17 11:37:02 AEDT 2012

Cell Phone Hackers Can Track Your Location Without Your Knowledge
Feb. 16, 2012

[Picked up from Lauren Weinstein's list]

Cellular networks leak the locations of cell phone users, allowing a 
third party to easily track the location of the cell phone user 
without the user's knowledge, according to new research by computer 
scientists in the University of Minnesota's College of Science and 

University of Minnesota computer science Ph.D. student Denis Foo 
Kune, working with associate professors Nick Hopper and Yongdae Kim, 
and undergraduate student John Koelndorfer, described their work in a 
recently released paper "Location Leaks on the GSM Air Interface" 
which was presented at the 19th Annual Network & Distributed System 
Security Symposium in San Diego, California.

"Cell phone towers have to track cell phone subscribers to provide 
service efficiently," Foo Kune explained. "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 result is that the tower will broadcast a page to your phone, 
waiting for your phone to respond when you get a call, Foo Kune said. 
This communication is not unlike a CB radio. Further, 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.

Cellular service providers need to access location information to 
provide service. In addition, law enforcement agencies have the 
ability to subpoena location information from service providers. The 
University of Minnesota group has demonstrated that access to a cell 
phone user's location information is easily accessible to another 
group -- possible hackers.

"It has a low entry barrier," Foo Kune said. "Being attainable 
through open source projects running on commodity software."

Using an inexpensive phone and open source software, the researchers 
were able to track the location of cell phone users without their 
knowledge on the Global System for Mobile Communications (GSM) 
network, the predominant worldwide network.

In a field test, the research group was able to track the location of 
a test subject within a 10-block area as the subject traveled across 
an area of Minneapolis at a walking pace. The researchers used 
readily available equipment and no direct help from the service 

The implications of this research highlight possible personal safety issues.

"Agents from an oppressive regime may no longer require cooperation 
from reluctant service providers to determine if dissidents are at a 
protest location," the researchers wrote in the paper. "Another 
example could be thieves testing if a user's cell phone is absent 
from a specific area and therefore deduce the risk level associated 
with a physical break-in of the victim's residence."

Foo Kune and his group have contacted AT&T and Nokia with low-cost 
techniques that could be implemented without changing the hardware, 
and are in the process of drafting responsible disclosure statements 
for cellular service providers.

Visit http://z.umn.edu/fookuneresearch to read the full research paper.

Roger Clarke                                 http://www.rogerclarke.com/
Xamax Consultancy Pty Ltd      78 Sidaway St, Chapman ACT 2611 AUSTRALIA
                    Tel: +61 2 6288 1472, and 6288 6916
mailto:Roger.Clarke at xamax.com.au                http://www.xamax.com.au/

Visiting Professor in the Faculty of Law               University of NSW
Visiting Professor in Computer Science    Australian National University

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