Lesson 2: Virus Catagories
Worm
Worms are one of the newest breeds of computer threats. Worms spread from computer to computer without the use of any host files, which means that the worm spreads itself in its entirety on to the next victim. Worms generally are not harmful, but can contain another virus within the worm coding. Worms are almost always designed to see just how far they will spread, but they can be just as dangerous as other more obviously damaging viruses can. If enough computers on one Internet Service Provider (ISP) have been infected with a worm the amount of email sent can skyrocket. This dramatic increase in traffic uses significant bandwidth, since ISP purchase blocks of bandwidth once the bandwidth maximum is reached the system may slow to a crawl or shut down completely. The Klez worm took advantage of a vulnerability in Microsoft Outlook and Outlook Express allowing it to automatically run the attachment as soon as you read the email, this allowed it to spread very quickly. Microsoft acted quickly to correct the vulnerability by releasing a patch for the Outlook programs.
