That's the conclusion of a study on the leakage of personally identifiable information on social networks done at AT&T Labs and the Worcester Polytechnic Institute.

The , which appears to have received scant public attention so far, was presented by the study's two researchers at a conference in Barcelona more than a month ago. Earlier this week, civil liberties group Electronic Frontier Foundation (EFF) referred to the study in a blog post.

The research, by Craig Wills of Worcester Polytechnic and Balachander Krishnamurthy of ATT, presents "some interesting technical details" on how social networking sites are leaking personal data, .

"In some cases, the leakage may be unintentional, but in others, there is clever and surreptitious anti-privacy engineering at work," the EFF said.

Wills told Computerworld that he and Krishnamurthy surveyed 12 of the biggest social networks for the study. They discovered that 11 of them were leaking personal identity information to third-parties including data aggregators, which track and aggregate user viewing habits for targeted ad-serving purposes.