Researchers at Stanford University and University of California at Berkeley found that major Web sites use “supercookies” to track online visitor behavior.

Supercookies aren’t deleted when the user clears his or her cookies inside the Web browser. History stealing is a similar way to gain information about online visitors without them knowing by looking at Web search history.

The Wall Street Journal reports that tracking online visitor behavior is legal, but as Internet privacy continues to be a huge topic of Interest, lawmakers are feverishly pushing for legislation against it.

Researchers at Stanford noted MSN.com as one of the Web sites using supercookies to track visitor behavior. Companies like MSN.com, a branch of Microsoft (News - Alert), use this information as way to deliver targeted ads to online visitors based on their behavior.

Mike Hintze, associate general counsel at Microsoft, said when the supercookie issue "was brought to our attention, we were alarmed. It was inconsistent with our intent and our policy." He stated the code was removed soon after.

Hulu (News - Alert), an online content streaming company, released a statement after researchers found it was also using supercookies, saying the company “acted immediately to investigate and address” the issues. Hulu was also involved in a $2.4 million class-action lawsuit related to placing cookies within Flash content.

Jonathan Mayer, a Stanford researcher, found that popular online movie fan site Flixster.com, and Charter Communication’s Charter.net, used a technique called history stealing to peer into Web history of online visitors. These sites reportedly used the information to see if people were searching for topics like ‘credit repair’ or ‘fertility problems’, which are big markets in the advertising industry.

In the case of Flixster and Charter.net, Mayer determined the history stealing was initiated by Epic Media Group, a NY-based digital marketing company. Charter and Flixster claimed no direct affiliation with Epic, but Epic’s advertisers had installed the history stealing code at these sites.

Epic Media Group’s CEO Don Mathis stated the technology was inadvertently used in the cases of Flixster and Charter and is no longer used. Flixster and Charter have since removed all Epic technology from each respective site.

It’s estimated that 80 percent of online ads are driven by tracking data. While the online ad industry launched a program to place labels on these types of ads, researchers found only about nine percent of the ads they investigated had the labels in place.

Legislation regarding Internet privacy is sure to stay a hot topic. Lee Peeler, executive VP of the Council of Better Business Bureaus, stated “You can expect to see more formal public enforcement soon."