Hundreds of thousands of ordinary apps, including popular ones such as 9gag, Kik, and a series of caller ID apps, are part of a global surveillance capability that starts with ads inside each app, and ends with the apps’ users being swept up into a powerful mass monitoring tool advertised to national security agencies that can track the physical location, hobbies, and family members of people to build billions of profiles, according to a 404 Media investigation.404 Media’s investigation, based o...