virus
[from the obvious analogy with biological viruses, via SF]
n. A cracker program that searches out other programs and `infects'
them by embedding a copy of itself in them, so that they become
Trojan horses. When these programs are executed, the embedded
virus is executed too, thus propagating the `infection'. This
normally happens invisibly to the user. Unlike a worm, a
virus cannot infect other computers without assistance. It is
propagated by vectors such as humans trading programs with their
friends (see SEX). The virus may do nothing but propagate
itself and then allow the program to run normally. Usually,
however, after propagating silently for a while, it starts doing
things like writing cute messages on the terminal or playing
strange tricks with the display (some viruses include nice
display hacks). Many nasty viruses, written by particularly
perversely minded crackers, do irreversible damage, like
nuking all the user's files.
In the 1990s, viruses have become a serious problem, especially
among IBM PC and Macintosh users (the lack of security on these
machines enables viruses to spread easily, even infecting the
operating system). The production of special anti-virus software
has become an industry, and a number of exaggerated media reports
have caused outbreaks of near hysteria among users; many
lusers tend to blame everything that doesn't work as
they had expected on virus attacks. Accordingly, this sense of
`virus' has passed not only into techspeak but into also popular
usage (where it is often incorrectly used to denote a worm or
even a Trojan horse). See phage; compare back door;
see also UNIX conspiracy.
