The 4. variant of the Zafi worm is spreading since yesterday. Worm.Win32.Zafi.D has a size of 11,745 bytes and is packed with FSG. It spreads via email as a christmas greeting and also via file sharing networks. In addition to the spreading mechanism Worm.Win32.Zafi.D installs a Backdoor on the computer which enables remote administration of the machine.
A more detailed description of the worm can be found at the a² Malware Database: click here