Facebook tracks non-users, logged-out users outside its platform: Report

According to a new study by Private International, Facebook tracks even those Android users who do not use the app.

It said Facebook routinely tracks users, non-users and logged-out users outside its platform through Facebook Business Tools.

App developers share data with Facebook through the Facebook Software Development Kit (SDK), a set of software development tools that help developers build apps for a specific operating system, the study said.

Typically, the data that is automatically transmitted first is events data that communicates to Facebook that the Facebook SDK has been initialized by transmitting data such as "App installed" and "SDK Initialized".

This data reveals the fact that a user is using a specific app, every single time that user opens an app.

"In our analysis, apps that automatically transmit data to Facebook share this data together with a unique identifier, the Google advertising ID (AAID)," the researchers said.

The primary purpose of advertising IDs, such as the Google advertising ID (or Apple's equivalent, the IDFA) is to allow advertisers to link data about user behavior from different apps and web browsing into a comprehensive profile, according to the report.

We also found that some apps routinely send Facebook data that is incredibly detailed and sometimes sensitive. Again, this concerns data of people who are either logged out of Facebook or who do not have a Facebook account. A prime example is the travel search and price comparison app "KAYAK", which sends detailed information about people's flight searches to Facebook, including: departure city, departure airport, departure date, arrival city, arrival airport, arrival date, number of tickets (including number of children), class of tickets (economy, business or first class).