Mercator Perspectives

Browsers Beware: Tracking Is Not Anonymous

Those websites that capture and sell browser-sourced data have often defended their actions by claiming that the data is anonymized or aggregated so as not to be personally identifiable. Researcher Jonathan Mayer at The Center for Internet and Society of the Stanford University Law School released results this week of a new study of the data distribution activities of 185 high volume U.S. websites. His blog cuts to the chase with respect to his findings:

“Click the local Home Depot ad and your email address gets handed to a dozen companies monitoring you. Your web browsing, past, present, and future, is now associated with your identity. Swap photos with friends on Photobucket and clue a couple dozen more into your username. Keep tabs on your favorite teams with Bleacher Report and you pass your full name to a dozen again. This isn't a 1984-esque scaremongering hypothetical. This is what's happening today.”
Julia Angwin reported on the quantitative findings for the Wall Street Journal

“He [Mayer] found that 61% of the websites transmitted identifying information to at least one outside web domain. ….. He [also] found that 45% of sites transmitted to at least four separate domains – which he said was a more robust representation of the amount of data sent to outside companies.”

Academic researchers add great value to the privacy debate by answering questions about “what really happens” in a technical context that average Internet users cannot independently examine. It is noteworthy that 39 percent of the firms Mayer studied did not, apparently, transmit any identifying data to third parties, although other data may have been sent.

Most of the data, including the user-identifying elements, tends to end up the hands of aggregators and resellers such as BlueKai and Lotame, whose data-analytics tools specialize in putting user identities back together with real-world personal identities. Until the U.S. adopts a more rigorous data privacy policy, one can only assume that one’s browsing habits, attached firmly to one’s real identity, are for sale to the highest bidder.

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