Trojans horse programs are increasingly prevalent in the wild and are becoming more troublesome than ever before. Even so, most people do not fully understand the capabilities, methods, and impact that a Trojan can have on a compromised computer. Unfortunately, most Trojan incidents are never reported, unlike massive worm outbreaks. As a result, thousands of Trojans are successfully deployed against specific targets on a weekly basis. This article overviews Trojans, qualifies the risk of such malicious code attacks, and overviews a common Trojan in the wild today, Assassin.