Hardly a day goes by when you don’t read about a new virus or worm spreading its way across the Internet. In a constantly escalating battle, virus authors find new ways of attacking machines as antivirus vendors try to find new ways to prevent viruses. As an IT Professional, you find yourself caught in the crossfire, trying to strike a balance between keeping your users safe while also not inhibiting their productivity.

Viruses and worms are two distinct, but related afflictions. Viruses are usually spread with the help of a third-party program such as Outlook. The virus will come in an e-mail and launch when a user double-clicks an attachment. The virus launches, doing its damage and replicating itself. Examples of viruses include:

  • Melissa
  • SoBig
  • Arcam
  • Karga

A worm on the other hand doesn’t need the help of a third party program. Once launched by the hacker, a worm self-replicates. It searches for vulnerabilities in a system and exploits them. After it “burrows” into a computer, it launches attacks on other computers, searching for the same vulnerabilities that it used to infect the host computer. Examples of common worms include:

  • Sasser
  • MSBlast
  • NetSky
  • MyDoom

A final class of malware that falls within the virus realm is the Trojan. Just like its namesake the Trojan horse, the Trojan masquerades as a legitimate program. When a user executes the Trojan, it then reveals its true nature, causing damage to the user’s computer. Examples of common Trojans include:

  • Flipe
  • Bing
  • Blank.A
  • Upbit