Sophos is advising Facebook users to exercise extra caution following the discovery of a malicious third-party application that exploits the widespread interest over changes to the site’s terms of use. This comes less than a week after another rogue third-party application called "Error Check System" sent messages to Facebook users claiming that there was a problem with their profiles, sending concerned users to malicious websites as they searched for information.

The application, named "F a c e b o o k -- closing down!!!" sends messages to everyone in a Facebook user's contact list, encouraging recipients to also add it - giving those behind the application access to victims' profiles and personal information.

The bogus notification messages claim that a friend has reported the victim for violating Facebook's terms of service. A typical message sent by the application reads as follows:

'[Friend's name] has just reported you to Facebook for violating our Terms of Service. - This is your official warning! - Click here to find out why you were reported! - Request Facebook look at what has happened and rule immediatley."

By clicking on the link, the victim not only allows the hackers to access his or her profile and personal information, but also unwittingly forwards the bogus message to all of their Facebook friends.

Facebook has since removed the application, but there are reports that similar rogue applications with names such as "My account" and "Reported For Rule Breaking" are currently circulating on the popular social networking site.