As Facebook users flock to delete their accounts following scares last week about privacy, warnings have been made about a new viral threat.

Websense claimed that new malware is making its way across Facebook in messages that purport to contain ‘the sexiest video ever'. When a user clicks on the ‘video' they are taken to an application installation screen asking them to allow it to access their profile. Once approved it claims they have to download an updated FLV Player to view the video and promptly sends an EXE to the user.

It detected this as the Hotbar Adware that displays ads in your browser based on your browsing habits, etc. In addition, the Facebook application will post messages on your friends wall on your behalf with the same ‘sexiest video ever' message.

Speaking on a video detailing the attack, Patrick Runald, security research manager at Websense, claimed that despite many people ‘liking' the video application from K-Multimedia on its fan page, it had a low review with only one star out of five. He said: “But that did not stop people from installing it as they really wanted to see this video.”

Sophos detected that the message has what appears to be a movie thumbnail of a woman on a bicycle wearing a short skirt, and the video's length is given as 3:17. Senior technology consultant Graham Cluley warned users to be ‘extremely careful on this occasion'.

He said: “Judging by the number of messages posted on Facebook, thousands of people received this attack. If you were one of them, you should scan your computer with an up-to-date anti-virus, change your passwords, review your Facebook application settings, and learn not to be so quick as to fall for a simple social engineering trick like this in future.”

Meanwhile, Sophos was among many security vendors who detected that 'Delete Facebook account' was trending on Google on Friday and over the weekend. Cluley warned: “That must mean that a lot of people are investigating how to delete their Facebook account right now. Facebook's bosses might be wise to rethink some of their policies, and make their users' privacy and safety online their prime responsibility.”

Sunbelt Software also reported that a graph from Google Trends showed that there were ten times as many searches for 'delete Facebook Account' recently as there were in 2008, and the rate has been rising through 2009 and rose at a much steeper rate recently.

Facebook played down reports of a crisis meeting over its problematic privacy policy at the end of last week, when it claimed that it was ‘providing a forum for employees to ask questions on a topic that has received a lot of outside interest.' 

Commenting, Ed Rowley, product manager at M86 Security, said: “It is encouraging to see that they are trying to protect its users by adding new security measures, as cyber criminals are so well-organised and well-funded that it is unlikely the platform will remain watertight for long.

“Unfortunately, adding granular security settings to anything involving individual user accounts, including Facebook, can be quite complex. It is likely that many of these security measures will remain options that Facebook users will simply ignore.

“What people forget is that Facebook is an organisation that seeks to generate money and make a profit. They don't charge users and therefore they have to make money via other means. Facebook's chief asset other than advertising space is the private and personal profile information, preferences and habits they hold about Facebook members.

“Whatever they may say about the security changes being considered, Facebook and its owners will unlikely want to cut off this potential gold mine without a fight. Users must continue to think before they post, spend some time changing the security settings on their account and read the Facebook Terms of Agreement.”