An investigation of the Australian Tv shows 60 minutes showed how a massive security hole in modern telecommunications is exposing billions of mobile phone users to illegal activities.

The program showed how German hackers were able to intercept and record the calls of an Australian senator and track his movements.

Mobile phone calls and data are wide open to interception because of flaws in the architecture of the signalling system – known as SS7 - used to enable mobile phone roaming across telecommunications providers.

Under international agreements all telecommunications providers have to provide details of their subscribers automatically via the SS7 system on request from another provider: the SS7 request immediately provides the name and contact details of the phone account subscriber, whether their phone is allowed to roam internationally, what kind of account they use and it also shows the nearest cell phone tower to which that mobile phone is currently connected.

Using this information, a determined hacker with access to the SS7 system can actually listen in to any mobile phone conversation by forwarding all calls on a particular number to an online recording device and then re-routing the call on to its intended recipient with the man-in-the-middle attack undetected. It also allows the movements of a mobile phone user to be geo-tracked on an application like Google Maps.

After the demonstration, the Australian senator,who agreed to take part in the hacking demonstration, called for an immediate full public inquiry into SS7:

"This is actually quite shocking because it affects everyone. It means anyone with a mobile phone can be hacked, can be bugged, can be harassed. The implications of it are enormous and what we find is shocking is that the security services, the intelligence services, they know about this vulnerability," he told 60 Minutes.

Source: http://www.computerweekly.com/news/4500251809/Mobile-phone-users-at-risk-as-hackers-bug-and-track-victims