Thanks to an issue with the Session Initiation Protocol (SIP), employed for voice calls and instant messages over LTE, those rockin' an Android phone running on AT&T or Verizon, are vulnerable to being attacked. This is the conclusion that appears on an advisory posted by Carnegie Mellon University. The latter based its paper on a report by Korean academics and security researchers. AT&T and Verizon users could be the victims of eavesdropping and data spoofing. While T-Mobile customers were also mentioned as being vulnerable, the carrier says that it has taken care of the issue.
Part of the problem lies from Android's lack of an "appropriate permissions model" for LTE networks. A malicious app can be used to have your phone silently dial premium numbers (which could end up padding your bill by a large dollar amount), and a hacker can obtain bandwidth to make video calls with no extra charge. If the exploit isn't patched, attackers can use a peer-to-peer network to steal personal content from your phone. And by creating multiple SIP sessions simultaneously, a DOS attack can be made against a network.
"We also propose immediate countermeasures that can be employed to alleviate the problems. However, we believe that the nature of the problem calls for a more comprehensive solution that eliminates the root causes at mobile devices, mobile platforms, and the core network."-ACM
"Current LTE networks rely on packet switching, rather than the circuit switching of previous generations of the mobile network. The use of packet switching and the IP protocol (particularly the SIP protocol) may allow for new types of attacks not possible on previous generation networks. Such types of attacks are well-known in the security community; for example, see previous attacks against Voice over IP (VoIP)."-CERT
Google plans on closing this hole with its November monthly security update for Nexus phones. AT&T and Verizon will have to fix the issue on their own networks. No word yet from the two largest U.S. carriers on how they intend to handle this problem.