Disable system addons

Mozilla silently distributed the Telemetry Coverage extension to 1% of Firefox users, collecting limited "anonymous" data even when the telemetry prefs are disabled.

To prevent these experiments in the future it could be a good idea to do this:

user_pref("extensions.systemAddon.update.url", "");
user_pref("extensions.systemAddon.update.enabled", false);

and also emptying the features subdir in the profile directory.

[pyllyukko]

Thanks for reporting this. What about the toolkit.telemetry.coverage.opt-out that they keep talking about? I couldn't find any reference into that setting (in the source etc.).

toolkit.telemetry.coverage.opt-out is specific to the Telemetry Coverage addon and "does not exist by default and must be created, if set to true then the extension should not send a payload as above for users in the 1% sample (such as the Telemetry client ID above will be)" (source)

[pyllyukko]

toolkit.telemetry.coverage.opt-out is specific to the Telemetry Coverage addon

Ok. Makes sense.

Apparently Mozilla devs now claim these addons are...

• "mid-release updates" and shouldn't be disabled

• "none of those extensions are experimental, and they are all being rolled out to 100% of the userbase." "...deployed to 100% of users, but only 1% will be sampled."

• "security, stability and performance updates are deployed using system add-ons."

source: https://old.reddit.com/r/firefox/comments/9ii8sj/firefox_keeps_silently_installing_hidden/

[Atavic]

I don't trust them anymore, so I'm opting out.