When a user with the extension visits a new webpage, the extension sends details about the page to Avast's servers, which then respond with security information While anyone can get the extensions, people installing standalone security software from both companies will see a message encouraging them to get the extension. Palant says he's spotted problems with extensions from AVG and Avast (which As part of that work, he pays close attention to how extensions interact with web browsers and user's computers. Mozilla acted after online posts by Wladimir Palant, who operates a major ad-blocking service. That's where a user is tricked into typing in personal details into what they think is a legitimate site. In this case, the advertised purposes include highlighting and blocking malware that could be downloaded, and warning users when a page may be part of a phishing attack.

The extensions are third-party tools for the Firefox browser that add extra functionality to web browsing.

It says the tools are collecting too much personal data about users. Mozilla has removed security tools from Avast and AVG from the Firefox extension store.

Avast blocking sites firefox