Click Fraud
Some crackers aren't interested in using zombie computers to send spam or cripple a particular target. Many take control of computers as a method of phishing, which is where a cracker tries to uncover secret information, particularly identification information. Crackers might steal your credit card information or search through your files for other sources of profit. The cracker might use a key logging program to track everything you type, then use it to discover your passwords and other confidential information.
Sometimes crackers will use zombie computers in ways that don't directly harm the victim of the initial attack or even the ultimate target, though the end goal is still pretty sneaky and unethical.
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You've probably seen or even participated in several Internet-based polls. Perhaps you've even seen one where the results seemed unusual or counter-intuitive, particularly when it comes to a contest. While it's entirely possible the poll wasn't ever attacked, crackers have been known to use zombie computers to commit click fraud. Click fraud refers to the practice of setting up a botnet to repeatedly click on a particular link. Sometimes, crackers will commit click fraud by targeting advertisers on their own Web sites. Since Web advertisers usually pay sites a certain amount of money for the number of clicks an ad gets, the cracker could stand to earn quite a few dollars from fraudulent site visits.
Zombie computers and the crackers responsible for them are pretty scary. You could end up being the victim of identity theft or unknowingly participate in an attack on an important Web site. It's important to learn how to protect yourself from crackers as well as what you should do if you find out your computer has been compromised.
In the next section, we'll look at what security measures you should employ to prevent your computer from becoming a zombie.