W32.Perrun is a virus that appends itself to JPEG files. The malicious content of files that it alters will not spread to other computers. Indications of infection are that .jpg files will have increased in size by approximately 11KB, and the presence of the file Extrk.exe. Variants: W32.Perrun.dr Type: Virus Infection Length: 11,780 bytes Systems Affected: Windows 3.x, Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Me