The name of a Trojan virus goes back to Greek mythology: the robbery of beautiful Helena triggered a war in ancient Greece. The Greeks around Agamemnon marched against Troy and besieged the city for over 10 years. The cunning Odysseus finally suggested building a wooden horse and placing it outside the city as a peace gift. The unsuspecting Trojans enjoyed the gift and rolled the horse into the city center. In the middle of the night the Greeks, who had been hiding inside the horse, climbed out and were able to beat the defenders and take Troy.

Just like in this myth, the computer version of a Trojan horse is also down to business. A malicious program hides behind a facade and pretends to be useful. If the program is executed in good faith, the true form is shown and the virus is triggered.
Towards the end of the 1980s, the first Trojan viruses, which were spread with blackmail intentions, made their rounds. Programs, which encrypted private data and should only be decrypted after a certain amount had been paid, were hidden behind the appearance of useful data. From the 2000s, Trojan horses were primarily used to put spyware into operation on a wide variety of systems. In 2005 Sony BMG, which had hidden a Trojan virus on their music CDs, gained negative awareness. The associated spyware collected information about the music behavior of the user and sent it directly to Sony. It should also be prevented that music CDs are illegally copied and distributed. Several virus programmers used this Trojan, which is widely used by Sony, to put their own malware into circulation.

The so-called federal trojan also became known. This means software that is to be used by the German federal authorities on PCs, but also on smartphones and other mobile devices. The software is designed to prevent, research and combat crime. This form of digital search is highly controversial and can also be misused by officials for private purposes.
In order to effectively protect against Trojans viruses, the installation and use of programs from unknown sources should be avoided. Above all, reference should be made to the use of illegal copies of known programs, but the illegal downloading of music or film files can also involve Trojan horses. Effective protection is also guaranteed by the combined use of anti-virus software with a firewall. The anti-virus software rarely recognizes the Trojan horse as such, but the malware installed with it and can therefore immediately isolate and block it. If the virus is too new and cannot be recognized by the anti-virus software, the firewall takes effect. It blocks all unauthorized communication, which means that the spyware programs that are often installed by Trojans cannot function.

If you suspect that you have accidentally installed a Trojan virus (this can be signaled, among other things, by slowing down the system, longer boot times, but also by suddenly appearing advertisements or tool bars), you should not only perform a detailed virus scan with a good anti-virus software are carried out, but at best the computer system is reset. This can be done by importing a clean backup copy of the hard disk, which should be created at regular intervals.