Trojan Horses

Abstract

A Trojan horse is a common type of rogue software. Such a program hides in a computer and has some malicious function. In contrast to viruses and worms, Trojans do not replicate. This chapter summarizes the main features of Trojans and also discusses how to modify a compiler in a devious way, to make it plant Trojans in programs that it compiles.

The Trojan war, described by Homer (Greek Oμηρoς) in the Iliadand the Odyssey, took place about 3200 years ago, in the beginning of the twelfth century b.c.. We don’t know whether the war actually happened or even if Homer existed, but throughout history (and even today) this chapter of Greek history has fascinated readers and writers alike and has inspired countless stories, poems, plays, and archaeological excavations. The Iliad describes how, having failed to capture Troy after ten years of siege and war, the Greeks, on the advice of Odysseus, made a giant wooden horse, left it at the gates of Troy, ostensibly as a peace offering, and pretended to sail away. The Trojans, intentionally confused by the Gods, dragged the horse inside the city walls and celebrated their “victory.” At night, Greek soldiers emerged from the horse’s hollow belly and opened the city gates, allowing their compatriots to pour in and capture and destroy Troy.