1. [n]  a large hollow wooden figure of a horse (filled with Greek soldiers) left by the Greeks outside Troy during the Trojan War
2. [n]  a subversive group that supports the enemy and engages in espionage or sabotage; an enemy in your midst

Trojan Horse
A retelling of the infamous story in which Greeks used a wooden horse to win the ten-year-long Trojan War. Full color.

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(Coined by MIT-hacker-turned-NSA-spook Dan Edwards) 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! A Trojan horse is similar to a back door.

See also RFC 1135, worm, phage, mockingbird.

[Jargon File]