February 02, 2011, 3:50 PM — Facebook has quietly fixed a vulnerability discovered recently by two student researchers that allowed malicious websites to access a Facebook user's private data without permission and post malicious links onto their profile.
See also: Social Media Risks: The Basics
Students Rui Wang and Zhou Li contacted security firm Sophos and told them the flaw they found made it possible for any web site to impersonate other sites which had been authorized to access users' data such as name, gender and date of birth. In other words, if a user has accessed any site - such as YouTube, or gaming sites and news sites -- and had given the site access to their Facebook profile, the potential was there for a malicious site to have access to their sensitive data. The researchers also found it was possible for the malicious site to pose as a legitimate web site and publish content on the visiting users' Facebook wall -- a common way malware is spread on the social network.
The user was at risk if they were to visit a malicious web site while logged into Facebook. The flaw was the result of a problem with in one of Facebook's authentication mechanisms. The students explain the problem in a YouTube video found here.
The vulnerability has already been addressed by Facebook, since the students practiced responsible disclosure and informed Facebook's security team about the flaw. Facebook Security responded by fixing the vulnerability quickly, according to Sophos' Graham Cluley.
"Clearly Facebook's website is a complex piece of software, and it is almost inevitable that vulnerabilities and bugs will be found from time to time," said Cluley. "The risk is compounded by the fact that there's so much sensitive personal info about users being held by the site -- potentially putting many people at risk."
Facebook has fixed many research-discovered bugs in recent years. Earlier this year it patched a flaw that allowed private chats to be made public. Last week, Facebook announced new security enhancements on the site.