Christopher Soghoian, a doctoral candidate at the School of Informatics and Computing at Indiana University, wrote on his blog that Facebook could deal with the issue in a couple of ways.
The site could simply stop allowing advertisers to target ads based on sensitive information, such as sexual preference or political affiliations, or it could inform users that an ad was targeted based on a specific attribute of their profile, Soghoian wrote.
"Users should also be told, after clicking on the ad, but before being directed to the site, that the advertiser may be able to learn this sensitive information about them, simply by visiting the site," Soghoian wrote. "I suspect that neither option is going to be something that Facebook is going to want to embrace."
The research paper, "Challenges in Measuring Online Advertising Systems," was written by Saikat Guha of Microsoft Research India, and Bin Cheng and Paul Francis, both of the Max Planck Institute for Software Systems in Germany.