Firefox Introduces Enhanced Protection Against Redirect Tracking

In the nightly builds of Firefox, which will form the basis for the Firefox 127 release on June 11, a new user tracking protection mechanism called “Bounce Tracking Protection” has been added. This feature expands Firefox’s ability to block tracking of visitors through redirects to other pages.

How Redirect Tracking Works

The essence of this tracking method is that tracker code first redirects the user to its own site, and only then forwards them to the target page. This allows the tracker to save cookies and data in local storage tied to its own site. By retaining this data after the user moves to another site, trackers can bypass the cross-site operation blocking methods implemented in Enhanced Tracking Protection (ETP). Since the intermediate page opens outside the context of the original site, tracking cookies can be set without restriction.

How Bounce Tracking Protection Works

The Bounce Tracking Protection mechanism detects activity specific to redirect-based tracking and periodically clears cookies and locally stored data used for tracking. Unlike the previously available “Cookie Purging” mode, which relied on a list of known trackers, this new protection uses heuristics to identify new tracker sites by analyzing behavior after a redirect.