US cell towers might be snooping on users’ cell calls

A significant number of cell towers in the US might be snooping on users' calls, The Register reported.

Experts say, despite being a standard that had been devised nearly a quarter of a century ago, GSM was still secure. If one was looking into listening into calls, it was actually much easier to just switch off the encryption. According to Les Goldsmith, the CEO of ESD America, which sells a security-hardened phone, he had found a number of cell sites which did exactly that.

Goldsmith told Popular Science he knew of 17 mobile phone towers, which forced his phone to 2G and then switched off the encryption. He dubbed these as ''interceptors'' on the basis that they might be running man-in-the-middle attacks where the rogue tower took a call, siphoned it off for interception and also passed it on to the legitimate network.

Meanwhile, Dave Lewis reports in Forbes that at the 2010 DEF CON in Las Vegas, security researcher Chris Paget did the unthinkable by building acell tower of his own for roughly $1500 to see if it spoof legitimate towers to  intercept calls.

Paget's device would only capture 2G GSM phone calls. According to Forbes, carriers such as AT&T and T-Mobile would be vulnerable as they used GSM, unlike Verizon which relied on CDMA technology.

Lewis said he was present at this particular presentation and had a disposable phone with him at the time. During the presentation when the device was switched on his phone was more than happy to oblige and seamlessly associated with the contraption that was across the room. He writes had he not been aware that what was going on, it was quite conceivable that he may not have noticed the role of the rogue tower.