Hackers Can Read Your Private SMS and Listen to Phone Calls

Security researchers have discovered a massive security flaw that could let hackers and cybercriminals listen to private phone calls and read text messages on a potentially vast scale – no matter if the cellular networks use the latest and most advanced encryption available.

The critical flaw lies in the global telecom network known as Signal System 7 that powers multiple phone carriers across the world, including AT&T and Verizon, to route calls, texts and other services to each other. The vulnerability has been discovered by the German researchers who will present their findings at a hacker conference in Hamburg later this month.

“Experts say it’s increasingly clear that SS7, first designed in the 1980s, is riddled with serious vulnerabilities that undermine the privacy of the world’s billions of cellular customers,” said The Washington Post, which first uncovered flaws in the system earlier this year.

SS7 or Signaling System Number 7 is a protocol suite used by most telecommunications operators throughout the world to communicate with one another when directing calls, texts and Internet data. It allows cell phone carriers to collect location information from cell phone towers and share it with each other. A United States carrier will find its customer, no matter if he or she travels to any other country.

According to the security researchers, the outdated infrastructure of the SS7 makes it very easy for hackers to hack, as it is loaded with some serious security vulnerabilities which can lead to huge invasions of privacy of the billions of cellular customers worldwide.

“The flaws discovered by the German researchers are actually functions built into SS7 for other purposes – such as keeping calls connected as users speed down highways, switching from cell tower to cell tower – that hackers can repurpose for surveillance because of the lax security on the network,” the report reads.

So far, the extent of flaws exploited by hackers have not been revealed, but it is believed that using the flaws hackers can locate or redirect users’ calls to themselves or anywhere in the world before forwarding to the intended recipient, listen to calls as they happen, and record hundreds of encrypted calls and texts at a time for later decryption.

No matter how much strong or advanced encryption the carriers are using, for example AT&T and Verizon use 3G and 4G networks for calls, messages, and texts sent from people within the same network, but the use of that old and insecure SS7 for sending data across networks the backdoor open for hackers.

Not just this, use of SS7 protocol also makes the potential to defraud users and cellular carriers, according to the researchers.

The American Civil Liberties Union (ACLU) has also warned people against using their handset in light of the breaches.

“Don’t use the telephone service provided by the phone company for voice. The voice channel they offer is not secure,” principle technologist Christopher Soghoian told Gizmodo. “If you want to make phone calls to loved ones or colleagues and you want them to be secure, use third-party tools. You can use FaceTime, which is built into any iPhone, or Signal, which you can download from the app store. These allow you to have secure communication on an insecure channel.”

Soghoian also believes that security agencies – like the United states’ NSA and British security agency GCHQ – could be using these flaws. “Many of the big intelligence agencies probably have teams that do nothing but SS7 research and exploitation. They’ve likely sat on these things and quietly exploited them,” he said.