An anonymous reader writes: Princeton privacy experts are warning that advertising and analytics firms can secretly extract site usernames from browsers using hidden login fields and tie non-authenticated users visiting a site with their profiles or emails on that domain. This type of abusive behavior is possible because of a design flaw in the login managers included with all browsers. Experts say that web trackers can embed hidden login forms on sites where the tracking scripts are loaded. Because of the way the login managers work, the browser will fill these fields with the user’s login information, such as username and passwords. The trick is an old one, known for more than a decade but until now it’s only been used by hackers trying to collect login information during XSS (cross-site scripting) attacks. Princeton researchers say they recently found two web tracking services that utilize hidden login forms to collect login information. The two services are Adthink (audienceinsights.net) and OnAudience (behavioralengine.com), and Princeton researchers said they identified scripts from these two that collected login info on 1,110 sites found on the Alexa Top 1 Million sites list. A demo page has been created to show how the tracking works.
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