Many mobile carriers have invested billions upon billions of dollars to upgrade their network infrastructures to support 4G LTE, but just like many modern marvels the network itself does have an Achilles’ heel.
A recent Virginia Tech study found that wiping out 4G LTE signal in a large area won't be that hard. According to the study, the control instructions that regulate the LTE signal makes up less than 1 percent of the overall signal being sent. Hence, all a person has to do is ‘jam’ that 1 percent of the signal and down goes the network. A crucial portion of this 1 percent is the time synchronization and signal synchronization that helps mobile LTE devices communicates with the towers. By transmitting an amplified signal with the same frequency as the synchronization signal, it is possible to disrupt the entire network in a large area.
“Your phone is constantly syncing with the base station. If you can disrupt that synchronization, you will not be able to send or receive data,” said Marc Lichtman, a research assistant in the study.
(Jam your neighbor's 4G with this radio unit)
Something like a $650 software-defined radio unit drawing power from a car battery can serve as the disruptive contraption. Although the idea sounds simple enough, it does take a bit of technical LTE knowledge and engineering know-how to actually carry out this experiment.
Jamming the synchronization signal is just one method that may be used to disrupt LTE service, as there are about 8 point of attacks in total. The LTE signal is made up of subsystems, and if one subsystem goes the whole thing gets spoiled.
“There are multiple weak spots—about eight different attacks are possible. The LTE signal is very complex, made up of many subsystems, and in each case, if you take out one subsystem, you take out the entire base station,” according to the researchers.
One could say that even if LTE service gets disrupted, there is still 2G and 3G to fall back on. However, that may not be the case as many carriers are beginning to phase out the previous standards and promoting the latest.
(Verizon currently boasts the most 4G coverage in the United States)
The LTE study itself found possible weaknesses to the LTE infrastructure, but according to the researchers there aren’t any permanent solutions as of yet.
“Although we’ve identified the problem, we don’t necessarily have the solutions. It’s virtually impossible to bring in mitigation strategies that are also backward compatible and cover it all,” said one of the researchers.
“LTE does a good job of covering [digital cellular systems]. But unconventional security aspects, such as preventing signal jamming, have been largely overlooked,” said Jeff Reed, the director of the research group.