Creepy Crawlers

Aside from cookies and software contained Spy-Ware, Web-tracking techniques are even more sophisticated--and harder to combat. The latest threat to online privacy in this camp is: Web bugs.

Unlike cookies, Web bugs show up as tiny image files embedded in a Web page or an HTML-formatted email message. They're usually invisible--so tiny, you'd never notice them--and they gather information ranging from your computer's IP address to your surfing habits, including the type of browser you're using. They're particularly nefarious because you can't see them, and anti-cookie filters won't catch them.

Web bugs are increasingly common. In fact, the White House ordered its own drug policy office to stop using Web bugs to target surfers with anti-drug advertising on the government's anti-drug Freevibe.com.

In addition to capturing surfing information and IP addresses, Web bugs can "talk" to cookies on your computer left by the same site or advertising company. Online ad company Double-Click , for example, used Web bugs that could communicate with cookies from its Web site. The cookies then revealed past online behavior, even home addresses, IP addresses, and phone numbers to the bugs, and the bugs sent that information straight back to Double-Click.

A company can also use the bugs to tie cookie histories to personal identifying information, such as your phone number and address. In fact, a California woman sued Double-Click for just that behavior. The company bought another firm, Abacus Direct, which holds detailed consumer profiles on more than 90 percent of U.S. households. Double-Click cross-referenced its Spy-Ware results with that database to compile surprisingly personal profiles.