A group of mobile security researchers at the Technical University of Berlin have recently discovered a security hole in the nation’s elderly GSM (2G) communications network that could give a small handful of cellphones the power to disable calling and text service to an area twice the size of Manhattan. The revelation was delivered as part of a paper presented at the Usenix Security Symposium in Washington D.C. last week.
Normally, when a phone call is placed or a text message is sent, cell towers send out a signal trying to find the intended recipient’s phone. By making a small modification to the baseband processor of a common Motorola phone, it was discovered that a hacker could intercept those search signals and prevent their delivery.
According to the study it would only take 11 phones to shut down GSM phone service in a 200 square kilometer (77 square miles) area. Explains head researcher Jean-Pierre Seifert to MIT Technology Review: “All those phones are listening to all the paging requests in that area, and they are answering ‘It’s me,’ and nobody in that cell will get an SMS or a phone call.”
Naturally, the goal of the researchers is to expose security holes that need patching before they can be maliciously exploited. The problem here is that preventing hacks on these antiquated (but still-used) networks would likely prove expensive – possibly too expensive to merit doing without an immediate threat.