quinta-feira, 23 de novembro de 2006

Video: The New Attack Frontier

NOVEMBER 21, 2006 Careful playing that video file: It could be infected. Researchers say video files are becoming the new mode of transportation for malware.

There's been a recent increase in proof-of-concept code for embedding malware in Windows Media and RealMedia files, for instance. The first known exploit using such a technique was spotted last week by McAfee; it was a worm aimed at Real Networks' RealPlayer and RealMedia files. Although the so-called W32/Realor.worm is considered a low-risk exploit, it opened the door for similar attacks via video players, security experts say.

Video is the new frontier for attackers. "This is one of the top attack vectors you should be concerned about. The potential [damage] is pretty massive," says Mark Zielinski, security engineer for Arbor Networks' Security Engineering and Response Team.

The Realor worm basically uses an infected hyperlink in a video file, and to do its dirty work it requires that a user click the poison link.

Attackers used to stick malware executables in an email attachment, but those typically get stopped at the email gateway, so attackers have resorted to using known applications as a way to deliver their malicious code.

These types of attacks aren't limited to video files. Zielinski says there's been an increasing number of vulnerabilities being published in Word, PowerPoint, and Real Networks' RealPlayer. "This kind of attack exists in any format where an application is willing to render an image."

If one of these attacks makes it successfully into the corporate network, it typically sets up a backdoor, so the victimized computer sends a connection back to the attacker, and the hacker doesn't have to initiate the connection, Zielenski says, and it can get by the firewall. It would be a popular method for a targeted attack, he says.

At the heart of the problem is the fact that video and audio formats -- as well as "workshare" apps like Word and PowerPoint -- contain multiple, complex features that leave them prone to attack, says Dimitri Alperovitch, principal research scientist with Secure Computing. "Those are files piquing the interest of virus writers... At the beginning of this year, we saw an increase in worms targeting Microsoft Office."

"As these applications become more and more bloated with features, this threat will continue to rise," he says, as well as with those video players that automatically load an embedded link in a video file when you open a video file.

"Old video files were just sets of frames you could view and create video applications [with]," he says. "Now you can insert all kinds of things into a video file: information about it, external links, etc. That presents more possibilities for exploitation."

YouTube is a prime candidate for attack, as well as other multimedia sites. Arbor's Zielinski says all it would take is an attacker downloading a video from YouTube, injecting his exploit, and re-uploading it, and then anyone who viewed it would get infected. "If there were 20,000 people viewing a popular video, they would get [infected]."

How do you protect yourself from a video attack? Aside from running the usual antivirus and host-based IPS tools, you should trust no outside sources.

"Be careful which documents you open," says Secure Computing's Alperovitch. "Nowadays, you can't trust any sort of data file you get from someone you don't know."

— Kelly Jackson Higgins, Senior Editor, Dark Reading

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