What is a Trojan?

Before we add to the already existing confusion, let me tell you that in this article we aren't going to talk about the Trojans from the city of Troy but about the Trojan virus which is one of the most dangerous computer viruses of present times. However, having some knowledge about the Trojan war will surely prove helpful here. Remember, the Trojan horse the ancient Greeks had sent to the city of Troy? Well, this virus is of the similar nature. In simple terms, it portrays itself as genuine content available for download and then spreads throughout the system. Let us check out in detail what this virus is all about and what it can do.

What is a Trojan Virus?

According to Cisco systems, " It is a harmful piece of software that looks legitimate. Users are typically tricked into loading and executing it on their systems." The term obviously comes from the same Trojan Horse story that we can discussed before. This type of a virus is Malware which basically means malicious software. 83% of the malware found on the Internet is Trojan. This virus disguises itself as a particular application or toolbar you would want to download. Once you click on the download option, it will instead download the Trojan on your system. This virus can then send out important information from your computer to the hacker. Different Trojan Horse viruses perform different functions as mentioned below. Removing a Trojan horse virus can be done with the help of Antivirus software.

What Are the Types of Trojans?

Remote Access Trojans
These are the most commonly used Trojan viruses wherein the attacker can access all files stored in the downloader's system after downloading this virus. Important information such as credit card numbers etc can be accessed.

Password Sending Trojans
This Trojan directly affects your passwords that are cached on your system. After these passwords are recognized on your system, they are directly sent to another e-mail address. Any new passwords fed into the system while this virus exists will also be sent to the same.

Key Loggers
This type of Trojan virus will log the victim's keystrokes and then these log files are sent to the client. It searches of data in the log files with two functions, offline and online. Even in this situation, the data can be sent to a particular e-mail id.

Destructive Trojans
This Trojan virus is capable of deleting all the files on the victim's or downloader's computer. You can also program this virus in such a way that it gets activated on a particular date at a particular time and then deletes all the files.

Denial of Service (DoS) Attack Trojans
This Trojan virus tries to congest the Internet connection. It does so by producing a lot of Internet traffic on the downloader's server or his/her computer. It also performs another function as an e-mail virus wherein it tries to pass onto many other computers and infect them by attacking a lot many e-mail addresses.

Proxy/Wingate Trojans
These Trojans change the downloader's computer to a Proxy/Wingate server. After this, the entire world can acquire access to a lot many Internet sites anonymously. Using information the client can then register many other sites and that too, without even being traced.

FTP Trojans
These are the most outdated and simple Trojan viruses. They perform only one action and that is to open or start a port numbered 21. This is the port for FTP transfers. Any computer can then connect to yours through FTP protocol. Since the more advance version are protected through passwords, the only computer that can connect to yours is that of the client or attacker.

Software Detection Killers
These Trojans get rid of the famous firewall or antivirus software programs. After this, the programs can no longer protect your computer and thus the attacker can get complete access to your computer or machine.

I hope you aren't still wondering what is a Trojan. As we have learned, we need to be careful with this Trojan virus. Not only because of its deceiving nature but also because of the harm it can cause.