Worms are actually sub-class of viruses. A computer virus is not unlike a biological virus. It is a self-replicating computer program that spreads by inserting copies of itself into other executable code or documents. The insertion of a computer virus into the program is called an “infection.” The infected file or executable code that is not part of a file is called a “host.” Viruses are one of the several different types of malicious software or “malware.”

Worms can spread from computer to computer, travel across networks, and copy your address book in order to send itself to all of your contacts. Worms can freeze or disable entire servers. Some of the most sophisticated worms can actually tunnel into your computer and give users remote access to your system. One of the most notorious of these is the Blaster Worm. The Blaster Worm, created in part by an 18-year-old kid from Minnesota back in 2003, spread on computers running Windows XP and Windows 2000. The worm was also called “Lovsan” and “Lovesan.”

While viruses and worms can spread, much like an infection, there is one malicious software program that does not self-replicate. However, it can be just as harmful to your computer as a virus or worm. It’s called a “Trojan Horse.”

A Trojan Horse, or just “Trojan,” will present itself as a helpful program, but once you install it on your computer, it will wreak havoc on your system almost immediately. A Trojan Horse may appear in the form of a file or software program that has been sent from a legitimate source. The Trojan Horse will install and a number of things can happen. Some Trojans will simply rearrange your desktop or add annoying icons to your desktop and others will delete entire files. Some of the more advanced Trojans can open the door to predators looking to steal your identity. These types of Trojans can give users unlimited access to your system.

Trojan and Worm Removal Tools

To get rid of downloadable viruses such as Trojans, worms or any other malicious software there are a number of free Trojan and worm removal software tool downloads available on the web. It is important to make sure that that the worm removal tool download is from a trusted source. If you are running Windows, stick with Microsoft software downloads. Microsoft offers its “Windows Malicious Software Removal Tool” free of charge for its Windows operating system. The great thing about this free Trojan and worm removal tool is that it updates once a month and reports if malicious software is found.

Other malware and worm removal tools include: Norton AntiVirus and McAfee Antivirus. These software programs are not free. It is important to note that while the Microsoft Software Removal Tool helps remove infections, it does not prevent them. If you want added security, it’s best to install Norton or McAfee as well.

From Microsoft:

The Microsoft Windows Malicious Software Removal Tool checks Windows XP, Windows 2000, and Windows Server 2003 computers for and helps remove infections by specific, prevalent malicious software including Blaster Worm, Sasser, and Mydoom. When the detection and removal process is complete, the tool displays a report describing the outcome, including which, if any, malicious software was detected and removed. The tool creates a log file named mrt.log in the %WINDIR%\debug folder.

Version 1.30 adds Win32/Allaple to the list of malicious software this tool detects.

You can download directly from the Microsoft website or Cnet.com.