Wiretapping Made Easy

Wiretapping Made Easy

Silently tapping into a private cellphone conversation is no longer a high-tech trick reserved for spies and the FBI. Thanks to the work of two young cyber-security researchers, cellular snooping may soon be affordable enough for your next-door neighbor.

In a presentation at the Black Hat security conference in Washington, D.C., a new technique for cracking the encryption used to prevent eavesdropping on global system for mobile communications (GSM) cellular signals was demonstrated. Combined with a radio receiver, this technique allows an eavesdropper to record a conversation on these networks from miles away and decode it in about half an hour with just $1,000 in computer storage and processing equipment.

In fact, GSM encryption was cracked – theoretically – in academic papers as early as 1998. "Active" radio interceptors, which impersonate cell towers and can eavesdrop on GSM phone conversations, have also been sold for years.

That means, that the cheaper technique presented in Washington is simply drawing needed attention to a problem that mobile carriers have long ignored – one that well-financed eavesdroppers may have been exploiting for years.

The new technique may serve as a wake-up call for mobile carriers, which have long been in denial about the vulnerabilities of GSM security, says Bruce Schneier, encryption expert and chief technology officer of BT Counterpane.

"This is a nice piece of work, but it isn't a surprise," he says. "We've been saying that this algorithm is weak for years. The mobile industry kept arguing that the attack was just theoretical. Well, now it's practical."