Most popular social networking site Facebook is in trouble after being attacked by unknown hackers. Vulgar images, Internet links and pornographic videos have hit some people's Facebook newsfeeds in the last few days. Facebook Inc said on Tuesday that it is investigating a rash of unsolicited graphic images that have hit some users' accounts this week.

Facebook

Facebook Attacked

We experienced a coordinated spam attack that exploited a browser vulnerability, Facebook spokesman Andrew Noyes said in a statement emailed to Reuters. Our efforts have drastically limited the damage caused by this attack, and we are now in the process of investigating to identify those responsible, he added.

Facebook users were tricked into pasting and executing malicious javascript in their browser URL bar, which led to them unknowingly sharing the content, Noyes explained. Facebook does not know yet who was behind the attack and the motive was not clear. Facebook engineers have been working to reduce this browser vulnerability, he added.

Social networking site Facebook and other Web 2.0 sites are easy targets for such attacks because they pull in a lot of content from outside sources, according to Paul Ferguson, senior threat researcher at Trend Micro Inc.

It seems every other day there is some new Facebook 'threat,' but this is just the new reality of Web 2.0 and social networking, Ferguson said. It is 'low-hanging fruit' for criminals, he added.