Tito's Blog

Antivirus companies warned PC users Tuesday that future Macromedia Flash movies could carry malicious viruses and worms.

The caution came after an unknown virus writer sent just such an infectious program to U.K. antivirus company Sophos. Dubbed SWF/LFM-926, the new program does little but infect Flash files on a PC when the movie is played.

It’s only when a Flash file or movie is played on a PC through a standalone player included with Macromedia’s authoring tools for Web designers that this type of virus can actually infect a PC.

When the infected Flash movie is played, the virus displays the message “Loading.Flash.Movie…” and drops a 926-byte DOS file onto the PC. This file–named V.COM–is run by the virus and infects all other Flash files in the current directory. The SWF/LFM-926 virus’ name is derived from the abbreviation for Shockwave Flash, as Macromedia Flash used to be known, the displayed message and the size of the file.

The virus will infect only Windows NT, Windows 2000 and Windows XP systems, but has not yet been seen circulating the Internet. Moreover, since the virus doesn’t have a way to spread quickly, it’s unlikely to infect a large number of PCs in its current form, said Craig Schmugar, virus research engineer for security-software maker Network Associates.