Firefox hit by critical zero-day vulnerability

Mozilla has issued a warning that its popular Firefox browser contains a critical vulnerability that is being actively exploited by cybercriminals to distribute malware.

The vulnerability, which was previously unknown, is said to affect versions 3.5 and 3.6 of Firefox.

Security firm Norman reported that the Nobel Peace Prize website was distributing a Trojan horse via the exploit yesterday, although it’s obviously possible that other websites may also be serving up the vulnerability in an attempt to infect visiting users.

Sophos is issuing protection against the malware as Troj/Belmoo-A.

Mozilla says it is working on a fix, but in the meantime Firefox users might be wise to turn JavaScript off and use the popular…

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.