Facebook has been hit by a widespread attack spamming porn and violent images, security experts say.

Story highlights

NEW: Facebook hack exploited browsers to spread porn, violent images

NEW: The site says most of the offensive material has been removed

Members of hacker collective Anonymous claim they created a virus to attack Facebook

Facebook: No data or account information was compromised in the attack

CNN  — 

Facebook says a hack that exploited some Web browsers was responsible for a flood of porn, violent images and other graphic content that spread across the site over the past couple of days.

Spokesman Frederic Wolens said Facebook’s security team had been working to identify the cause of the spam and that, by Tuesday afternoon, “we have eliminated most of the spam caused by this attack.”

“We are now working to improve our systems to better defend against similar attacks in the future,” Wolens said in an e-mail.

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