The social networking site has fixed a bug that could have allowed attackers to users’ full names and photos, and to verify email addresses
Atul Agarwal of Secfence Technologies posted information about the issue to the Full Disclosure mailing list 11 August. If someone entered a user’s email address and the wrong password in the login page, the site coughed up the user’s full name and profile picture in addition to an incorrect password message.
“Some time back, I noticed a strange problem with Facebook, I had accidentally entered wrong password in Facebook, and it showed my first and last name with profile picture, along with the password incorrect message,” Agarwal wrote. “I thought that the fact that it was showing the name had something to do with cookies stored, so I tried other email IDs, and it was the same. I wondered over the possibilities, and wrote a POC tool to test it.”
The problem could have been exploited for social engineering purposes by phishers, or used to verify random email addresses by checking them against Facebook, Agarwal added.
In a statement, a Facebook spokesperson said the bug has been fixed, and added that the site’s policy prohibits anyone from scraping it for information.
“We have technical systems in place to prevent people’s names and profile photos from showing to unrelated users upon login, but a recently introduced bug temporarily prevented these from working as intended,” according to the spokesperson. “We remedied the situation swiftly.”
Earlier this year, Facebook revamped its privacy controls in response to criticism, and recently moved to extend those controls to users of the mobile version of the site.