Security News > 2021 > October > Mozilla Firefox Blocks Malicious Add-Ons Installed by 455K Users

The Firefox team said that the misbehaving Firefox add-ons they found in June - named Bypass and Bypass XM - were misusing the API to intercept and redirect users from downloading updates, accessing updated blocklists and updating remotely configured content.

Mozilla has blocked the malicious add-ons in order to keep them from being installed by yet more users.

Starting with Firefox 91.1, if an important request is made via a proxy configuration that fails, Firefox will resort to direct connections instead. "Ensuring these requests are completed successfully helps us deliver the latest important updates and protections to our users," the Firefox developers said.

What Firefox Users Should Do. First, make sure you're running on the latest version, which as of Monday was Firefox 93 or Firefox ESR 91.2.

Next, if you're using Firefox on Windows, make sure that Microsoft Defender is running, Mozilla said: "Together, Firefox 93 and Defender will make sure you're protected from this issue."

What Firefox Add-on Developers Should Do. Mozilla is asking all developers of add-ons that require the use of the proxy API to start including a strict min version key in their manifest.

News URL

https://threatpost.com/mozilla-firefox-blocks-malicious-add-ons-installed-by-455k-users/175745/