What’s a Trojan Horse?

Trojan Horses are programs that are disguised as useful software and are put for download on the Internet, and users download and run them only to realise their mistake later. The main difference between a Trojan Horse and a virus is that Trojans don’t spread themselves.

A Trojan Horse is divided into two parts- a server and a client. The server is cunningly disguised as important software by giving it an icon or double extension such as ‘filename.jpg.exe’. The icon can be of a program that is commonly used such as flash, winzip, winrar or photoshop. The server is placed in P2P (peer-to-peer) file sharing networks such as Kazaa or eDonkey 2000, or unofficial download sites. Once the server runs on your system the attacker can gain control over your system allowing the person to perform actions such as deleting,uploading and downloading.

The different types of Trojan Horses are:

• Remote Access Trojans :

  These are the most common form of Trojans. These give an attacker complete control over the victim’s computers. The attacker can go through the files and access any personal information about the user such as credit card information and passwords.

• Password-sending Trojans :

  These type of Trojans copy all cached passwords and look for other passwords as you enter them and send them to the specified e-mail address. The passwords for resticted Web sites, messaging services, FTP services and e-mail services are also copied without the user’s knowledge.

• Keyloggers :

  These are called keyloggers as they log every keystroke of the victim and then sends the logs to a specific e-mail address on a daily basis. The attacker then searches the logs for passwords or other sensitive data in the log files.

• Destructive :

  These type of Trojans get activated at a specific time and automatically deletes all the system files on your system.

• Denial of Service Trojans :

  These type of Trojans are also called as DOS Attack Trojans.They generate a lot of Net traffic on the victim’s machine, to the extent that the Internet connection is too overloaded to let the user visit a Web site or even download anything.

• Proxy/Wingate Trojans :

  These type of Trojans turn the victim’s computer into a proxy or wingate server so that the infected computer is available to everyone to be used for anonymous access to various risky Internet Services. The attacker can register domains with stolen credit cards or do similar illegal activities without being traced.

• FTP Trojans :

  These trojans open a port on your computer for FTP transfers and also lets the attacker connect to your computer. Most trojans today have this function.

• Software Detection Killers :

  These Trojans kill most popular antivirus and firewall programs that protect your system to give the attacker access to the victim’s system without being caught. This is another common function of a Trojan Horse.