Mozilla warns thousands have downloaded poisoned Firefox plugin

Advertising code inserted by the malicious Xorer worm has been discovered in a plugin for the Firefox web browser that has been downloaded thousands of times in the last three months.

Mozilla’s chief of security, Window Snyder, has confirmed in a post on her blog that HTML files in Firefox’s Vietnamese language pack were carrying a script (detected by Sophos as Mal/Badsrc-A) designed to display irritating advertising messages as users browsed the web. The affected files had been available for download since February 18 2008.  The script is not believed to have been planted…

Read more in my article on the Naked Security website.

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Graham Cluley •   @gcluley

Graham Cluley is a veteran of the anti-virus industry having worked for a number of security companies since the early 1990s when he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows. Now an independent security analyst, he regularly makes media appearances and is an international public speaker on the topic of computer security, hackers, and online privacy. Follow him on Twitter at @gcluley, on Mastodon at @[email protected], or drop him an email.