Over the past two weeks, Mozilla has reviewed and banned 197 Firefox add-ons because they were executing malicious code. The malicious Firefox add-ons were found stealing user data and for this reason, they were removed from the Mozilla Add-on (AMO) portal.
Mozilla also disabled the malicious add-ons in the browsers of the users who have already installed them.
The apps were using obfuscation to hide their source code and were downloading and executing code from a remote server, a behavior that violates the policy of the portal. Downloading code from a remote server could allow threat actors to execute malicious code within the browser once it will be dynamically downloaded from a server under their control.