Update: Facebook confirms nasty porn storm

Facebook users have been bombarded with explicit and violent images in the latest malware campaign aimed at the giant social networking site, a security researcher said today.

The company confirmed the attack and said it had “dramatically limited the damage” and was on the trail of those responsible.

“For the last 24 hours, many people have reported seeing highly-offensive images on their Facebook news feeds,” said Graham Cluley, a senior technology consultant at antivirus vendor Sophos, in an interview early Tuesday.

“But exactly how those images got there and what cause them to appear, is still somewhat of a mystery,” Cluley added.

Cluley speculated that the attack may have been based on “clickjacking,” which describes a type of attack where hackers plant invisible “buttons” on a website page. When a user clicks on the overlaying page component, they actually execute malicious code or script that can hijack their browser or personal computer.

Cluley also said it was possible that previous-planted malware conducted the Facebook spam campaign.

Later on Tuesday, Facebook filled in some of the blanks.

“We experienced a coordinated spam attack that exploited a browser vulnerability,” a Facebook spokeswoman said in an email. “Our efforts have drastically limited the damage caused by this attack, and we are now in the process of investigating to identify those responsible. “

The Facebook spokeswoman said the attack was based on a “self-XSS vulnerability in the browser,” but did not identify which browser or browsers contained the bug.

While XSS stands for “cross-site scripting,” the Facebook description reads more like clickjacking, the term coined by researchers Robert Hanson and Jeremiah Grossman in 2008 to describe a variant of cross-site scripting.

“Users were tricked into pasting and executing malicious JavaScript in their browser URL bar causing them to unknowingly share this offensive content,” Facebook said.

People took to Twitter to express their outrage over the images, which Sophos said ranged from modified celebrity photos to pictures of extreme violence and animal abuse.

“Has anyone been on Facebook lately? My newsfeed looks like a porn site,” said someone identified as Jay Ciroc on Twitter late Monday.

Earlier in the day, other researchers had pointed to a specific piece of malware that may have been responsible.

According to Romanian security vendor BitDefender, the hacker collective known as “Anonymous” crafted a classic Facebook worm, codenamed “Fawkes Virus” last July, and had pledged to use it to celebrate Guy Fawkes Day, Nov. 5, a promise that was unfulfilled.

Guy Fawkes was arrested Nov. 5, 1605, for his part in the Gunpowder Plot to assassinate King James I of England. Anonymous has often used a mask of Fawkes as a logo for its disruptive hacking campaigns.

Facebook did not respond to questions about whether the porn spam was launched by the Fawkes malware.

“The reaction has been very strong from Facebook users,” said Cluley, who cited users who said it was the final straw, and that they would abandon Facebook until it got its security house in order.

That may be a while.

“Facebook has made improvements, but the scale of the problem they face is enormous, what with its 800 million members and the target that makes them,” said Cluley. “I really, really hope Facebook can get a handle on spam and scams, but the spammers, the bad guys, are making just as much progress.”

Meanwhile, Facebook outlined the steps it had taken today to combat the pornography.

“We’ve built enforcement mechanisms to quickly shut down the malicious pages and accounts that attempt to exploit it,” the company spokeswoman said. “We have also been putting those affected through educational checkpoints so they know how to protect themselves [and] we’ve put in place backend measures to reduce the rate of these attacks.”

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg’s RSS feed . His e-mail address is gkeizer@computerworld.com.

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