McAfee reports that it's seen a huge spike in fake MP3 files spreading on peer-to-peer networks. Although the files have names that make them look like audio recordings, they're really Trojan horse programs that try to install a shoddy media player and adware on your computer, said Craig Schmugar, a researcher with McAfee.  "Once you run it, there is no content. You're taken to this site to install this player, which you don't really need," he said.  Fake file names include: preview-t-3545425-changing times earth wind .mp3 and t-3545425-just got lucky.mp3. Schmugar listed more filenames, as well as details on the adware, in a Tuesday blog posting. Users are first asked to OK an end-user license agreement before the Trojan installs two programs, Mirar and NetNucleus, on their PCs.

Ironically, while the Mirar software tells users that it doesn't display pop-ups, NetNucleus does deliver pop-up ads, so users who do not realize that they are installing two programs might feel tricked, Schmugar said. "You have a Window telling you that there are no pop-ups, and right behind it is a pop-up."