Major vulnerability in 5G means that anyone with $500 worth of gear can spy on a wide area's mobile activity

Stingrays (AKA IMSI catchers) are a widespread class of surveillance devices that target cellular phones by impersonating cellular towers to them (they're also called "cell-site simulators").

IMSI catchers are so easy to build and operate that they have leapt from police agencies to criminals, and foreign and corporate spies, exposing us all to potential surveillance from all quarters.

That's why it was so important that the new 5G mobile protocol be designed to foil IMSI catchers, and why the 3rd Generation Partnership Project, or 3GPP (the body standardizing 5G) updated the Authentication and Key Agreement (AKA) to resist IMSI catching techniques.

But new research from ETH Zurich and Technische Universitit Berlin has revealed a critical flaw in AKA, a defect that not only allows attackers to track the number of calls and texts being sent while a user is connected to the fake tower, but also a count of calls and texts from before the device was compromised. More importantly, the attack allows for fine-grained location tracking.

It's important to keep in mind here that, for cases of lawful intervention from law enforcement agencies, there are better ways than this attack technique to get location information, such as getting a warrant and getting the information directly from the phone companies. People working outside the legal system, such as spies and criminals, cannot get warrants and cannot typically work directly with the phone companies. Law enforcement does not need the location-finding capabilities of an IMSI catcher unless they are trying to circumvent the legal system.

The 5G Protocol May Still Be Vulnerable to IMSI Catchers [Cooper Quintin/EFF Deeplinks]