Facebook appears to be under a sustained attack from unknown sources. Thousands of users are reporting dubious, and often pornographic, images and links appearing on their wall without their knowledge over the last 24 hours.

These are know as linkspam viruses and when someone clicks on the link it spreads the virus further. This is not new, however in the past it was often related to a user giving a dubious Facebook application access to their wall.  The app/game appears to work fine for a period of time, however at some point in the future it will post to their wall.

Facebook have acknowledge the problem saying they are "aware of these reports and we are investigating the issue".

Some people are connecting this attack to the Anonymous group after a video appeared on YouTube threatening to "kill" the social network, however there is currently no evidence to support this theory.

Facebook recently stated that its service is constantly under attack, clocking up around 600,000 attempts every day.

Twitter is currently full of critics of the Facebook service and many are enraged at the content being auto-posted on their wall.

Facebook will need to react swiftly to discover the issue and reassure their users -- especially as they have a huge number of young users; their current policy allows users over 13 years of age to access the site.

Users should check their App Settings under Account Settings in Facebook to review apps that have access to their account.  Take a few minutes to remove any you do not need/recognise.

UPDATE:  Facbook fix the problem

site by DAJ