RSA 2012 The GSM mobile standard is wide open for attack, experts have warned, thanks in part to the increasing amount of computing power available to hackers.
"Voice interception capability really depends on how much processing power you have," said Aaron Turner, cofounder of security specialists N4struct, speaking at the RSA 2012 conference in San Francisco. "But that's just a function of Moore's Law – the faster computers get, the more data they can handle."
In their presentation at RSA 2012, Turner and cofounder of Arbor Networks Rob Malan detailed how easy it is to break into mobile phones, either to slurp data, monitor voice calls, spam users, or turn the device into a bugging station. GSM code is incredibly brittle, Malan explained, mainly due to lack of oversight in the standards, and ever-increasing computing power is making phone hacking more commonplace.
"GSM is a fascinating space to play around in, but GSM infrastructure is very, very brittle and ripe for attack," Malan warned. Mobile hacking has been limited in the past, because buying a cell tower and backend server to research weaknesses was beyond the means of most hackers, he said. But it's has now become possible to build mobile hacking systems for very little money, thanks to increased computing power and lower-cost radio equipment.
Hackers are also being helped directly by corrupt staff in mobile network operators, they explained. Once you have a target's phone number, it's possible to buy its international mobile equipment identity (IMEI) number for around $100 to $150, in many cases. Once the number is found, it's relatively easy to launch a brute force attack the GPRS protocols, since they sometimes use repeated passcodes, and gain access to the handset.
With equipment and information costing around $5,000, Turner estimates that you could build a monitoring network that would be capable of taking over a specified mobile phone at a range of up to 27 kilometers – and if you're willing to spend more, the range of activities available widens.
Surveillance is still a popular target for hackers. A hacked phone can be turned into a tracking device, or have its microphone switched on to transmit private conversations without alerting the owner. This is very useful for insider traders, for example, or to gain information for blackmail or competitive advantage.
For more-direct financial gain, hackers also use premium-rate SMS messages. Turner said that one group of US companies had lost millions after their mobile networks were hacked and users were tricked into sending out high-cost text messages.
He also warned that in some countries in South America, Asia, and the Middle East, telecommunications providers are colluding with hackers for mutual profit. He advised countries to check the record of their local supplier, disable software updates when roaming, and consider leaving the phone at home altogether.