An FTP Trojan is a special type of Trojan allowing the attacker to access a machine using the FTP Protocol.
Generally, a Trojan is a type of virus entering a system in an undetected manner and accessing all confidential data, thereby causing trouble by compromising or exposing data. One of the ways a Trojan can manifest itself is in the form of a genuine program performing malicious functions.
Techopedia explains FTP Trojan
An FTP Trojan installs an FTP server on the victim’s machine allowing the attacker to gain access to sensitive data through the FTP Protocol. The Trojan opens port 21 and makes it accessible to the attacker or a group of individuals. Some password attacks can also be employed where only the attacker gains access to the system. The system tries to download and upload files from the victim system.
The types of information affected include:
Credit card information
All types of username and password information
Email addresses to propagate
Using the victim’s computer as a source for propagating other attacks
Securing a Computer Against Trojan Attack
Anti-virus gateway protection can be employed to detect Trojans incoming through HTTP, email or FTP. It is recommended to use multiple virus engines to ensure that different types of Trojans are easily recognized and dealt with. A single virus engine can never recognize all Trojans.
The following are some steps to prevent or reduce the presence of Trojans:
Download only from trusted websites.
Check the file extension before opening it. (It is possible that a jpg file has been masked with an .exe extension, which can activate the Trojan by clicking it.)
Avoid executing web-based scripts and automated commands mentioned online without fully understanding their effects.
Download .exe files only from trusted sources.