Mozilla is introducing a new feature to Firefox aimed at protecting users from bounce trackers, the browser developer has announced. Bounce tracking is a technique where a user clicks a link but ends up reaching their intended destination via an intermediary tracking page. This allows trackers to place and read ‘first-party cookies,’ which aren’t blocked by the browser, unlike third-party cookies.
For instance, imagine a user on flowers.example clicking a link to books.example. At the last moment, the tracker active on the former site reroutes the link through tracker.example. The user first lands on this tracking page, which then redirects them to books.example, enabling tracker.example to identify that the user is interested in both flowers and books.
If tracker.example manages to inject itself into the user’s browsing pattern frequently enough, it can build a detailed profile of the user. To combat this, Mozilla has announced a feature called ‘Bounce Tracking Protection,’ which will regularly cleanse Firefox of tracking data every 24 hours. The browser will utilize heuristic detection methods to identify and recognize bounce trackers.
“This feature builds upon the principles of its existing Cookie Purging tech. Unlike previous methods that depend on a predefined list of trackers, Bounce Tracking Protection employs heuristic techniques to detect bounce trackers based on user navigation patterns. It’s designed in alignment with the emerging navigational-tracking-protections specification draft under the PrivacyCG. Initially introduced in Nightly under bug 1877432 in a ‘dry run mode,’ where we don’t yet purge tracker storage but merely gather telemetry, we are preparing to fully activate this feature soon. We aim to ensure its robustness and stability before its broader release,” the Mozilla dev team stated.
Currently, Bounce Tracking Protection is available in an early test version of Firefox. Although it isn’t fully enabled yet, data is being collected to refine the detection. Once the feature is stable, Mozilla will activate it in the test version and automatically clear tracker data.
