[comp.virus] Reasons anti-virus viruses are bad

XRJDM@SCFVM.GSFC.NASA.GOV (Joe McMahon) (08/17/90)

Assuming that your "nice" virus 1) works properly, 2) always asks
before doing anything, and 3) removes itself after doing its function,
there are still reasons why it's a bad idea.

1) This is a masterly set-up for a Trojan horse. Looks just like the
   "Nice Guy" virus, but it does (pick the nasty of your choice) instead.
2) Unforseen circumstances. New hardware, new versions of an operating
   system, etc., could cause bad things to happen.
3) Bugs. There will always be bugs.
4) No way to "guarantee a clean copy" - the current weak spot in all
   anti-virals. In the immortal works of Roseanne Roseannadanna, "You
   don't know *where* it's been!"
5) Mac virus clones have proved that there are people capable of taking
   a working virus and changing it. No doubt this would be done (see (1)).