Monday, July 24, 2006

MySpace Banner Ad Infects Million Users

A banner advertisement posted on the MySpace Web site may have infected more than one million users with adware, according to security firm iDefense. The advertisement was included in user profiles on MySpace and could have been operating for about one week.

The advertisement exploited a flaw in the way Microsoft's Internet Explorer (IE) browser handles Windows Metafile (WMF) image files. Users running unpatched versions of IE would never have realized that the banner ad had silently installed programs that generate pop-up ads on their system.

"This is a criminal act," said Hemanshu Nigam, chief security office at MySpace, in a statement. "This ad is being delivered by ad networks who distribute these ads to over a thousand sites across the Internet in addition to ours. We are working to have these ad networks remove this ad so that they do not appear on our site."

Banner Patch

An iDefense spyware analyst, Michael La Pilla, told The Washington Post that he discovered the attack on Sunday as he browsed the MySpace site. When he came across a page with the offending ad, he received a message from his browser asking him if he wanted to open a file named exp.wmf.

After a brief investigation, La Pilla found out that the spyware installation program contacted a Russian-language Web server in Turkey that tracks the PCs on which the program has been installed. The tally had climbed to 1.07 million machines, though La Pilla said the seven Internet addresses contacted by the downloader seem to be inactive now.

According to La Pilla, the ad also attempted to infect users of, a photo-sharing site. Though he cannot pinpoint the date the ads began sending out their spyware, it is believed that it coincided with the occurrence on MySpace on July 12.

The WMF vulnerability was originally discovered last December after hackers exploited the flaw using a specially created WMF image distributed via e-mail, instant message links, and Web sites. When users opened the image, the hacker could take control of the infected PC. Microsoft released a patch for the bug back in January, but many people did not install the patch.

PCs with unpatched systems can become infected simply by accessing a Web page with the ad. The exp.wmf Trojan horse program could upload automatically without the warning prompt that La Pilla received.

Once installed, PCs running the Trojan horse will contact multiple Web sites and download a slew of unwanted programs such as PurityScan advertising software. PurityScan is an adware program that can cause pop-up windows containing unsolicited ads to appear. The application also keeps track of the user's online activity.

Two Wrongs

Rob Ayoub, an analyst at the research firm Frost & Sullivan, said two facts stand out regarding the MySpace infections. First, home users are clearly not as educated about the need to make sure they have up-to-date patches and other security fixes installed. Second, MySpace needs to have a better security system to identify dangers hidden in the ads they serve.

If you are a legitimate business with a legitimate Web site hosting banner ads, you have a responsibility to keep the service clean, Ayoub said. "MySpace has some problems and this is a real blunder on their part. I can't believe any business would not scan or take more caution with banner ads posted on their sites. Ad network or not, there is no excuse for them not having a checking system."

One million people is a very large number, Ayoub said, and it demonstrates that the technology industry, and security firms and software makers in particular, might not have done enough to impress upon home users the importance of downloading patches. PCs that have not been updated exponentially increase problems with viruses, spyware and adware.

"MySpace should have been checking and users should have been patching," Ayoub said. "And because of that combination you have a million downloads."

Some PC users have said their reluctance to install patches and updates centers around the fear that any changes will negatively impact their computers. However, Ayoub pointed out, unwanted changes or problems with updates is relatively rare these days.

"There was a time when you had to watch and be very careful with your patches," Ayoub said. "And some of the big ones are a problem, but there haven't been big problems with patches for ages."

Home users, Ayoub predicted, will not start to take security seriously until Internet service providers start to make antivirus and antispyware software compulsory. That may or may not be the best solution, he said, but incidents like this are a "perfect storm" for users not protecting themselves.

"That's extremely dangerous," Ayoub said. "Maybe what we need to do is run public service announcements."

MySpace is "strongly" urging all Internet users to "follow basic Internet security practices such as running the latest version of the Windows operating system, installing the latest security patches, and running the latest anti-spyware and anti-adware software."

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