Your phone can communicate with Facebook even if you are not using Facebook.
A worrying number of popular Android apps are sharing user data with Facebook without user consent, new research from Privacy International shows (via Financial Times).
The worst part: Staying off Facebook doesn't protect you from this.
Privacy International, a London-based charity that focuses on improving people's privacy, reviewed 34 popular Android apps, each installed 10 million to 500 million times, between August and December 2018. All of these apps share data with Facebook through its software development kit (SDK), which is great if users have somehow consented to it. But the organization intercepts the data as it was sent (using a freely available, open-source tool) and found that at least 20 of these applications (about 61 percent) "automatically transfer data to Facebook the moment a user opens the app. "
Researchers claim that this happens even if the user is logged out of Facebook or does not even have a Facebook account.
Typically, apps communicate to Facebook that a user has started using the app by sending a signal that Facebook's SDK has been initialized. But Privacy International research shows that apps that automatically share this data do so together with a unique identifier called the Google Advertising ID. Some apps go even further, sending data to Facebook that Privacy International describes as "incredibly detailed and sometimes sensitive."
One example is the kayak trip search app, which sends detailed information to Facebook about users' flight searches, including data such as departure / arrival date, city and airport as well. as the number and class of tickets.