Security experts are warning of new Facebook security threat which arrives as a 'sexy' video posted on users' walls but installs adware on the PCs of unwary users.

Sophos senior technology consultant Graham Cluley said in a blog post that thousands of Facebook users have received messages on their walls, seemingly from friends, with the phrase: 'This is without doubt the sexiest video ever!: P :P :P.'

However, clicking on the video leads to an application installation page containing malware, warned Websense security research manager Patrik Runald.

"Once approved, it claims you have to download an updated FLV player to view the video, and promptly sends an [executable file] your way," he wrote in a blog post.

"This is the Hotbar adware which displays ads in your browser based on your browsing habits etc. In addition, the Facebook application will post messages on your friends' walls on your behalf with the same 'sexiest video ever' message."

Full story: V3.co.uk