They're keeping track by tracking the trackers that track you.
By Alfred Ng
When you download an app, the permissions requests and privacy policy are usually the only warnings you'll get about the data it's taking. Usually, you just have to take the app's word that it's grabbing only the data you've agreed to give it.
Often, though, there's more grabbing going on than you were led to believe, security researchers have determined. More than 1,000 apps have been found to take data even after you've denied them permissions. For instance, menstrual tracking apps have shared sensitive info with Facebook, as well as with other companies you might not have expected. Similarly, apps designed to block robocalls have shared your phone data with analytics firms.