A program that modifies other programs or
databases in unauthorized ways; esp. one that propagates a
virus or Trojan horse. See also worm
mockingbird. The analogy, of course, is with phage viruses in
biology.
Trojan horse: [coined by MIT-hacker-turned-NSA-spook Dan Edwards]
n. A malicious, security-breaking program that is disguised as
something benign, such as a directory lister, archiver, game, or
(in one notorious 1990 case on the Mac) a program to find and
destroy viruses!...