BitDefender, an anti-virus and PC protection company, has identified a Trojan that infects a users’ installation of Firefox, implementing an add-on masking itself as a popular addition to Firefox. Viorel Canja, head of BitDefender’s labs, said the Trojan (dubbed "Trojan.PWS.ChromeInject.A") sits inside the Firefox add-on folder and runs when Firefox is started. They recommend “installing effective Internet Security protection and making sure [home users] are updated regularly, to ward off these attempts,” and to stay safe online.

It is reported that the malicious add-on identifies itself as Greasemonkey, a popular add-on for Firefox – the version available from the Mozilla site is secure and unaffected. The virus identifies hundreds of banking and money transfer websites, including Paypal and Bank of America, and transmits the login details for these to a server hosted in Russia.

The news follows a recent report that the Vietnamese language pack for Firefox contained some malicious code, which caused users to view unwanted advertisements and has since been removed.