A Trojan or a Trojan horse is a program that hides in a useful program but once installed, it carries out unauthorized and harmful activities on the victim’s computer or network.
It derives its name from the infamous Trojan Horse story in Greek mythology, where a large wooden horse was used to sneak Greek soldiers inside the city of Troy. Similarly, Trojan horse malware deceives users by appearing harmless, but it contains hidden malicious code or functions that can steal sensitive information, gain unauthorized access, or perform other malicious actions without the user’s knowledge or consent.
A major difference between viruses and Trojans is that Trojans do not self-replicate. In Addition to launching attacks on a system, a Trojan can establish a back door that can be exploited by attackers.