IMSI catchers, otherwise known as stingrays, are those surveillance tools that masquerade as cell towers and trick mobile phones into connecting, spewing private data in the process. Law-enforcement agencies have been using them for awhile, but there's never been a good way for individuals to detect them. But that was before SnoopSnitch.
Released for Android on Monday, SnoopSnitch scans for radio signals that indicate a transition to a stingray from a legitimate cell tower. The app was created by German security researchers Alex Senier, Karsten Nohl, and Tobias Engel from SRLabs and presented at the Chaos Computer Congress. The group explains, "SnoopSnitch collects and analyzes mobile radio data to make you aware of your mobile network security and to warn you about threats like fake base stations (IMSI catchers), user tracking and over-the-air updates."
Currently, only rooted Android phones with Qualcomm chipsets collect the type of information that the app needs to detect stingrays (a lot of Sony smartphones and Samsung Galaxy handsets have the right chips), but the researchers are working on figuring out how to get the information they need from other configurations as well so the app can support more handsets.
The app can't protect people's phones from connecting to stingrays in the first place, but it can at least let them know that there is surveillance happening in a given area. Nohl told Motherboard that he thinks of SnoopSnitch as a "catcher catcher." He said, "There's no one set of information, taken by itself, that allows you to detect an IMSI catcher, but we do stream analysis of everything that happens on your phone, and can come out with a warning if it crosses a certain threshold."
A stingray protection cloak would be great, but for now just knowing when and where your phone is connecting to them could be useful.