Spreading through P2P networks as we speak, Trj/WmvDownloader.A and Trj/WmvDownloader.B exploit Windows Media Digital Rights Management (DRM) technology. Normally, this technology is used to provide Windows users with a valid license when they try to play a protected Windows media file. However, these Trojans pretend to download the corresponding licence for the files they infect, when in fact they are downloading adware, spyware, and diallers.
"Even though these Trojans have been detected in video files with extremely variable names which can be downloaded through P2P networks like KaZaA or eMule, bear in mind that they can also be distributed through other means, such as files attached to email messages, FTP or Internet downloads, floppy disks, CD-ROM, etc." - PandaLabs.