Friday, May 21, 2010

Facebook Leaks Usernames, User IDs, and Personal Details to Advertisers

Browse Facebook, and you wouldn't expect Facebook's advertisers to learn who you are. After all, Facebook's privacy policy and blog posts promise not to share user data with advertisers except when users grant specific permission. For example, on April 6, 2010 Facebook's Barry Schnitt promised: "We don't share your information with advertisers unless you tell us to (e.g. to get a sample, hear more, or enter a contest). Any assertion to the contrary is false. Period."

My findings are exactly the contrary: Merely clicking an advertiser's ad reveals to the advertiser the user's Facebook username or user ID. With default privacy settings, the advertiser can then see almost all of a user's activity on Facebook, including name, photos, friends, and more.

In this article, I show examples of Facebook's data leaks. I compare these leaks to Facebook's privacy promises, and I point out that Facebook has been on notice of this problem for at least eight months. I conclude with specific suggestions for Facebook to fix this problem and prevent its reoccurrence.


According to WSJ...

The practice, which most of the companies defended, sent user names or ID numbers tied to personal profiles being viewed when users clicked on ads. After questions were raised by The Wall Street Journal, Facebook and MySpace moved to make changes. By Thursday morning Facebook had rewritten some of the offending computer code.

Advertising companies were given information that could be used to look up individual profiles, which, depending on the site and the information a user has made public, include such things as a person's real name, age, hometown and occupation.

Several large advertising companies identified by the Journal as receiving the data, including Google Inc.'s DoubleClick and Yahoo Inc.'s Right Media, said they were unaware of the data being sent to them from the social-networking sites, and said they haven't made use of it.

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