This virus, which first appeared in late 1989, is the first virus which can spread from an infected disk without any action by the user. It is named after the Window DEFinition resource it uses to infect computers.
A second “strain” was discovered almost immediately; the strains are called WDEF-A and WDEF-B. The only significant difference is that WDEF-B beeps every time it infects a new Desktop file, while WDEF-A does not beep.
The WDEF virus infects the invisible
“Desktop” files used by the Finder. Every Macintosh disk has one of these files. The virus spreads from Desktop file to Desktop file, but it does not infect applications, data files, nor system files.
-- part contents for background part 11
----- text -----
The virus does not intentionally try to do any damage. In fact, it doesn't do anything except spread from disk to disk.
The following symptoms of a WDEF infection have been reported: the virus causes both the Mac IIci, the portable and any Mac with 8 Megabytes of memory to crash; it can cause crashes when trying to save files from applications under MultiFinder; and it cause problems with the proper display of font styles (the outline style in particular).