Sevendust virus would remove all files from the infected hard drive, but leave applications and one file named 666 in the Extensions folder. AutoStart, one of the first Mac worms, was also identified that year. The worm that exploited a feature in QuickTime 2.0 was first identified in Tokyo and overwrote data files on infected systems. AutoStart spread to other systems by floppy disk, recordable compact disks, hard disks and disk image files. The virus was discovered a few days before Halloween 1998.
Source: https://threatpost.com/sevendust666-autostart-9805/91956/