[from the obvious analogy with biological viruses, via SF] 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 became a serious problem, especially among
Windows users; the lack of security on these machines enables viruses to
spread easily, even infecting the operating system (Unix machines, by
contrast, are immune to such attacks). 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.
