The most damaging forms of malicious code—worms with names like Love Letter, SirCam, and Anna Kournikiva, to name a few—have all relied on social engineering techniques of deception and taking advantage of our desire to get something for nothing in order to be spread. The worm arrives as an attachment to an email that offers something tempting, such as confidential information, free pornography, or—a very clever ruse—a message saying that the attachment is the receipt for some expensive item you supposedly ordered. This last ploy leads you to open the attachment for fear your credit card has been charged for an item you didn't order.