Malware in Firefox Add-on

Mozilla is warning users about a malware that slipped into Firefox's Vietnamese language add-on and went undetected for months.

For a couple of months, Mozilla's servers were hosting a language pack for Firefox 2 infected with Xorer.O. The Vietnamese pack, which was uploaded on February 18 2008 and removed this week, had the malware 'embedded' because the author's PC was infected.

As the virus scanner of Mozilla's servers didn't get updated with the worm's signature until almost one month after the pack was uploaded, the infection went unnoticed for a couple of months.

Xorer.O can spread via removable media, including floppy disks, as well as network shares.

It is not known how many people were infected with the malware.

Other vendors have been hit with similar problems. In late 2006 Apple shipped Video iPods that contained the RavMonE.exe virus. Late last year, retailer Best Buy shipped digital picture frames that contained an unspecified malware which went undetected for months.