Protect Your PC From Trojans

Trojan horse programs are cleverly packaged software. These programs are usually bundled with a legitimate program such as a screen saver, video, game etc. Trojans can be installed on computers through thousands of free software packages that can be downloaded from the Internet. Once an unsuspecting user downloads the program and executes it, she triggers the installation of the Trojan along with the legitimate program.

Trojans consist of two components a client and a server. The server component gets installed on the victims PC and starts actively scanning the designated port for a client connection from the attacker. When the connection is established the attacker can send commands which are executed on the victim’s computer.

Trojans can have payloads such as:

Backdoor entry program (a attacker can remotely access your PC)
Keylogger (every keystroke you type is saved and transported the hacker),
Disable your security software such as anti virus program.
Setting up a network of zombie computers to launch a denial of service attack (DOS) on others computers.
Send spam from your computer

How do you know if your system is infected with a dangerous Trojan horse program? Look for these symptoms:

Increased disk activity even at times of no user activity
Internet connection slows down to a crawl
Memory usage is high
System reboots frequently

These symptoms could be an indication of dangerous Trojan programs such as keylogger program, backdoor entry, enrollment of your PC as a zombie on a botnet etc

There are some Trojan horse programs that cause minor annoyances such as:

PC screen turns upside down
Printer automatically starts printing
The mouse moves by itself
Computer shuts down automatically
PC background settings changed

A simple rule of the thumb is to be suspicious of any change in your system settings and any kind of automated activity such as your printer automatically printing, optical drive door opening and closing automatically, PC shutting down etc. Also it is a good idea to familiarize yourself with the running programs on your PC.

Most anti virus programs are capable of detecting and removing Trojans as well, so the steps to remove a virus are applicable to Trojans too.

If you are unable to remove a Trojan with a regular anti virus program you can try these specialized tools

Bit Defender - malware removal tools:

http://www.bitdefender.com/html/free_tools.php

ESET - malware removal tools:

http://www.eset.com/download/free-virus-remover.php

F-Secure - malware removal tools:

http://www.f-secure.com/download-purchase/tools.shtml

Kaspersky's malware removal tools:

http://www.kaspersky.com/removaltools.html

McAfee's Stinger - malware removal tool:

http://vil.nai.com/vil/stinger/