• by Wendy Davis , Staff Writer @wendyndavis, August 18, 2011

Several weeks ago, UC Berkeley researchers caused a stir with a new report stating that analytics company KISSmetrics was using ETag technology that can track people even when they delete their cookies.

Today, Stanford's Jonathan Mayer has posted new research showing that Microsoft uses ETags to track users. Microsoft apparently was using the technology within its own properties like Bing. But the company's scripts also gave Microsoft the ability to associate Atlas information -- collected from other sites -- with users' activity on Microsoft, Mayer says.

The only way for users to prevent ETag tracking is to clear their browser caches as well as their cookies. Microsoft, like KISSmetrics, has already disabled the code. "Microsoft promptly investigated Mr. Mayer's findings and determined that the cookie behavior that he observed was occurring under certain circumstances as a result of legacy code that was used only on some of our own sites and was already scheduled to be discontinued," said a spokesperson.

The company added that Microsoft didn't share any data about the cookie identifiers to be shared outside of the company.

That may be, but the fact that major companies like Microsoft deploy technology that circumvents users' preferences raises very troubling questions. Equally troubling is that Microsoft only took action after an outside researcher discovered how the company collected data.