The US Department of Justice is installing equipment on airplanes that masquerades as a cell phone tower in order to gather mobile phone data, according to a new report from The Wall Street Journal. The program's goal is to identify criminals, but each plane is capable of collecting data from thousands of phones in a single flight.
The Journal says these spy devices are called "dirtboxes," and have a surface area of two feet by two feet. They're being installed on fixed-wing aircraft by the US Marshals Service's Technical Operations group, and purport to be strong-signaled cell towers. This tricks cellphones into giving them their IMSI info, making them totally trackable.