What is the difference between viruses, worms, and Trojans? -

What is the difference between viruses, worms, and Trojans?
- Patrick

This question was answered on March 7, 2008. Much of the information contained herein may have changed since posting.

The world of computing has always had pranksters developing rogue software programs with ill intent, but these days, the intent is becoming more menacing.

Technically speaking, viruses, worms and Trojans are different transmission methods to deliver a malicious “payload”, usually to compromise your computer Knowing the differences can help you understand how to protect yourself from them all.

A computer virus is much like a human virus, in that it needs the help of a human to spread The most common way to get infected by a virus is to manually run a program that has the malicious code attached to it.

All viruses are avoidable because the user has to double-click or run the infected file in order to get infected The best way to avoid computer viruses is to avoid running any program or file attachment that you are not 100% sure about In addition, keeping your anti-virus program up-to-date will generally stop you from running an infected file before it has a chance to attack your computer.

The problem with relying on your anti-virus program to protect you all the time is that the bad guys have the upper hand Anti-virus program vendors can create protection against a new virus only AFTER it has been released in the wild and in most cases started to infect users.

Before the Internet connected us all together, the most common way to get infected by a virus was to run a program on a floppy disk that came from an infected computer, which meant virus spread was slow and anti-virus companies had the time to create and distribute updates.

Today, a new virus can spread across the world in a matter of hours if humans can be “tricked” into opening or running a file they get via e-mail, instant messaging or from a rogue website One of the key indicators that a file may be dangerous is if it has the .EXE extension, which means that it is an executable file.

You should never open or run an EXE file that you receive via e-mail, instant messaging or from a website unless you are absolutely sure of its validity.

A computer worm, unlike a virus, doesn’t need a human in order to spread A worm is capable of “worming” its way from computer to computer through a network without the assistance or knowledge of the infected party.

The Internet is the world’s largest computer network, so any one user is capable of spreading a worm to every other user on the entire network, which is why this method is so insidious.

One of the keys to defending yourself against worms is to install a firewall If you are on a high-speed (always on) Internet connection and you don’t have a firewall in place, the thousands of worms traversing the Internet every minute are capable of infecting you just because you are physically connected to the Internet.

Broadband “routers” (which are considered hardware firewalls) are a must have on today’s Internet because they provide a single point of protection for all the computers in your home or at your business Software firewalls should be considered a second layer of protection to be used in conjunction with a hardware firewall.

Trojans are programs that hide themselves inside of other programs and “jump out” once the carrier program has been run Users that like to download and install lots of free programs that they find on the Internet or on file sharing networks are at the highest risk of being infected by a Trojan.

Unfortunately, the vast majority of today’s attempts to infect you use a “blended threat” approach, which means a virus and a worm or Trojan are usually coded together in the same attack, so don’t let your guard down!