It seems that Mozilla has been tracking users of Firefox by using Google Analytics – without any notice nor any possibility for opt-out.
However, according to a statement, Google Analytics is only being used when choosing “suggested add-ons” in add-on manager. But also here, the user does not get any information or choice to refuse sending his private data to Google. Mozilla notices they have an agreement with Google that all data is completely anonymized – but recent analysis shows up that direct user-tracking is not necessary and even anonymized informations can clearly point to a specific user.
The MIT showed up a success rate of 95% for “anonymized data”, being able to point to specific users with only very few information
Tor browser tracking
A big problem is that currently Firefox is being used to create the Tor Browser – which should give you full anonymity in the net. It seems that even Tor Browser contains the “Analytics leak” – following the previous analysis of anonymized data there is a good chance to track the private data back to a specific user, even when using Tor for anonymity.
Even Firefox includes a “do-not-track” option, the setting was completely ignored for the add-ons page. From technical point, when choosing suggested add-ons in Firefox, an iFrame containing Google Analytics code is being loaded from Mozilla’s servers. Mozilla just released a new patch after which do-not-track option also stops the Analytics at suggested add-ons.
Tor Browser developers suggests to completely disable add-ons in the browser for security reasons. Currently this is only possible using the about:config options:
about:config?filter=extensions.webservice.discoverURL – delete complete value in the string