There is a very large number of user webspaces that have been attacked by the Gumblar virus (or a derivative of it)
If you are using a Windows based PC we urge you to:

• keep your antivirus software up to date
• scan your PC thoroughly

The virus acts by infecting a user's PC and then uses their FTP login details to install files on their website

NB: If your PC or that of one of your colleagues is infected you will need to clean it properly, as otherwise it will simply re-infect the site