This week was an unusually optimistic one for hundreds of thousands of Facebook users who found that their accounts were automatically endorsing numerous oddly entitled websites. If you have been avoiding Facebook, your closest Facebook user (anyone under the age of 30 is a safe guess) can explain that one way users have to share things with their friends, including websites, musicians, television shows, ideas and other users, is to click the ever-present "Like" button. Some have begun to call this new exploit "likejacking."
The culprit for this unintentional optimism appears to be a "clickjacking" worm that exploited a vulnerability in web browsers used to access the victim's Facebook account. While the victim is logged in to Facebook, his or her account will spontaneously "Like" web links with titles such as "LOL This girl gets OWNED after POLICE OFFICER reads her STATUS MESSAGE." As a result, a user's Facebook friends are encouraged to visit the sites. Clicking the link will take users to a website that states "Click here to continue" and clicking the message apparently causes subsequent users' accounts to begin the same automatic referrals to their friends.
If you have begun to notice that you are "Like"-ing websites more than usual, Sophos makes the following recommendation to users who have been infected:
If you believe you may have been hit by this attack, view the recent activity on your news feed and delete entries related to the above links. Furthermore, you should view your profile, click on your Info tab and remove any of the pages from your "Likes and interests" section.