A Trojan horse is a type of malware that disguises itself as legitimate code or software, but once inside the network, attackers are able to carry out any action they desire. Unlike viruses or worms, Trojan malware cannot replicate itself or self-execute, and it requires specific and deliberate action from the user. Trojans are designed to damage files, redirect internet traffic, monitor the user’s activity, steal sensitive data, or set up backdoor access points to the system. They may delete, block, modify, leak, or copy data, which can then be sold back to the user for ransom or on the dark web.

The name "Trojan horse" comes from the classical story of the Trojan War, where the Greeks used a wooden horse to enter the city of Troy and win the war. Similarly, a Trojan virus looks like legitimate software and tries to deceive the user to load and execute the files on the device. Once executed, the malicious code will execute the task the attacker designed it for, such as gain backdoor access to corporate systems, spy on users’ online activity, or steal sensitive data.

Trojan attacks have been responsible for causing major damage by infecting devices, services, or networks. They are one of the most common threats on the internet, affecting businesses and individuals alike. Trojan attacks can be disguised as legitimate programs, usually as an app or other commonly downloaded item, and can affect Windows, Mac, and mobile devices.

To protect against Trojan viruses, it is important to have up-to-date antivirus software, avoid downloading files from untrusted sources, and be cautious when opening email attachments or clicking on links.