Tro•jan horse

noun

1: the large, hollow wooden horse filled with Greek soldiers and introduced within the walls of Troy by a stratagem

2: a seemingly innocent computer program that is willingly downloaded by the user without suspicion, but when executed, activates hidden programming that performs malicious or unwanted actions

After the 1993 World Trade Center attack, a division of the Central Intelligence Agency established a domestic unit tasked with protecting America from the threat of terrorism. Headquartered in Washington, D.C., the Counter Terrorist Unit established field offices in several American cities. From its inception, CTU faced hostility and skepticism from other Federal law enforcement agencies. Despite bureaucratic resistance, within a few years CTU had become a major force. After the war against terror began, a number of early CTU missions were declassified. The following is one of them . . .