Your Online Privacy May be Leaky
More than a half billion people use social networking sites like Facebook to share personal information with friends and colleagues. According to a study co-authored by Craig Wills, professor of computer science, that information may also find its way to the third-party tracking sites that make it possible for websites to serve up ads that align with your web browsing habits.
Tracking sites have always stressed that they can't connect your browsing behavior directly to you— just to a particular computer you happen to use. But Wills found that many social networking sites have breached this barrier. When they communicate with tracking sites, they include the unique identifier—usually a string of numbers—that points to your online profile. In theory, that makes it possible to connect the record of where you go on the web with your name and other personal information.
In addition to privacy concerns, the practice opens the door to incorrect profiling (if other people use your computer, whose browsing behavior is being linked to you?) and misleading profiling (did you visit that site on cancer out of curiosity, or because you are sick?). In addition to publishing these findings, Wills has spoken about his work and concerns at a Federal Trade Commission Panel on online privacy. He and his co-author have also shared their results with all of the social media sites they studied, though none have yet responded.