Facebook Leaks Usernames, User IDs, and Personal Details to Advertisers
Through Krishnamurthy and Wills’ research, Facebook eight months ago received actual notice of the data leakage at issue. A September 2009 MediaPost article confirms Facebook’s knowledge through it spokesperson’s response. However, Facebook spokesperson Simon Axten severely understated the severity of the data leak: Axten commented “The average Facebook user views a number of different profile pages over the course of a session …. It’s thus difficult for a tracking website to know whether the identifier belongs to the person being tracked, or whether it instead belongs to a friend or someone else whose profile that person is viewing.” I emphatically disagree. As shown above, when a user views her own profile, or a page linked from her own profile, the “?ref=profile” tag is added to the URL — exactly confirming the identity of the profile owner

Amazing. This post shows you how shockingly complacent Facebook truly is with all that data. And it all flies in the face of their statements about user privacy vis-à-vis advertisers. I hope they have some response to this train wreck.