= V =
[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.
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.