Microsoft stops secretly tracking users' browsing habits

Firm blames 'supercookies' on 'older code'

Microsoft has removed code from its MSN web site that tracked its users' browsing habits, even if those users intentionally deleted their cookies in order to preserve their privacy.

Mike Hintze, associate general counsel, regulatory affairs, Microsoft, announced in a blog that the firm investigated the code once it was brought to its attention by a researcher.

"According to researchers, including Jonathan Mayer at Stanford University, 'supercookies' are capable of re-creating users' cookies or other identifiers after people deleted regular cookies.

"We determined that the cookie behaviour he observed was occurring under certain circumstances as a result of older code that was used only on our own sites."

Hintze added that the company removed the code, and reassured users that the information potentially gleaned from the "older code" had not been shared with external organisations.

"We quickly disabled this code. At no time did this functionality cause Microsoft cookie identifiers or data associated with those identifiers to be shared outside of Microsoft.

"We are committed to providing choice when it comes to the collection and use of customer information, and we have no plans to develop or deploy any such 'supercookie' mechanisms."

Separately, this month researchers found that new technologies such as HTML5, a language used for presenting certain web content, are being used by sites to store cookies and track visitors' web use.