Alarming Security Defects in SS7, the Global Cellular Network—and How to Fix Them
The network, called Signaling System 7, or SS7, is a digital signaling protocol that mobile phone carriers including AT&T, T-Mobile, and Sprint use to send messages to each other about who is a subscriber, where subscribers are located, and how calls should be routed to reach them.
SS7 began as a closed network shared among a few major mobile phone carriers, but grew porous as more carriers joined. Hackers and governments can now gain access by purchasing rights from a carrier (which many are willing to provide for the right price) or infiltrating computers that already have permission.
Once they’re in, hackers and government intelligence agencies have found ways to exploit security defects to monitor users or record calls. Experts who study SS7 have found some individuals are tracked by as many as nine entities at once. While the average citizen isn’t likely to be a target, it’s impossible for consumers to know whether or not they’re being watched.