US military officials were recently caught off guard by revelations that servicemembers' digital fitness trackers were storing the locations of their workouts - including at or near military bases and clandestine sites around the world. But this threat is not limited to Fitbits and similar devices.
My group's recent research has shown how mobile phones can also track their users through stores and cities and around the world - even when users turn off their phones' location-tracking services.
