Trojan

A Trojan is malware that is usually downloaded, mistaking it for legitimate software. The name refers to the semi-mythical story of the Trojan horse used by the Greeks to capture Troy in the 13th century BC (sometimes Trojan is called ‘Trojan’, which is incorrect because the Trojans were the victims).

A Trojan differs from viruses and worms in that it does not reproduce. It takes root in a computer, smartphone, tablet to operate unnoticed by the user. For example, it transmits personal information – bank card data, electronic documents, logins, passwords – to a third party. There are also proxy Trojans that use an infected device to send spam; spy Trojans that can read messengers; and backdoor Trojans that provide access with administrator rights (see a separate article on the latter). Trojans are also used as ‘spacers’ to annonymise hackers: unauthorised access to the banking network can be performed not from the attacker’s IP, but from the IP of the infected machine.

The Trojan is often downloaded together with ‘cracked’ software from torrent aggregators. In order to install software without a licence, you need to use a keygen (key generator) or a cracker. Trojans are disguised as such.

Another popular source is emails with attachments like a picture or other media file with an intriguing title. This option is more suitable for inexperienced users.

Trojans can also be found on fake sites, such as those that mimic the official sites of mobile operators. This was the case with Skygofree Android Trojan, discovered in 2018. Once downloaded, the Trojan gained full control over the smartphone, including Skype, Viber, Facebook Messenger and WhatsApp.