A worm, Koobface, that hit Facebook last December is again active with a fresh appeal.

The virus has not only targeted Facebook but also Friendster, hi5.com, livejournal, bebo, fubar, MySpace, myyearbook, netlog.com and tagged.com

The latest version of Koobface arrives as an invitation from a user’s friend, inviting the recipient to click on a link and view a video at a counterfeit YouTube website, with fake comments. Visitors are told they need to install an Adobe Flash plug-in to view the video.

What an art is that the malicious landing page pulls the photo from the Facebook profile of the inviter, according to Trend Micro blog.

Clicking the Install button installs the new Koobface variant detected as WORM_KOOBFACE.AZ.

In addition, the worm propagates through other social networking sites as well. It hijacks the victim’s account and sends additional invites to his contacts.

Users of the Trend Micro Smart Protection Network are protected from this threat, as per Trend Micro reporting.

So, be cautious while using such social networking sites. If possible, use the vendor’s site for downloading anything. Also, you can use any online antivirus.

So, be cautious while using such social networking sites. If possible, use the vendor’s site for downloading anything. Also, you can use any online antivirus.

But I would say that precaution is better than cure. So, download any software from the genuine sites and beware of social networking channels especially Facebook as it is being hit continuously by viruses from time to time. You should also have an updated antivirus installed and keep it upto date too.