Adware causes problems for MySpace users

More than one million users of MySpace.com may have been infected withadware spread by a single ad, according to iDefense, a computersecurity group.

The advertisement, for a site called deckoutyourdeck.com, appeared inuser profiles on MySpace, an online community with at least 70 millionusers, said Ken Dunham, director of the rapid response team atiDefense, a subsidairy of VeriSign.

The ad exploits a problem in the way Internet Explorer handles Windows Metafile (WMF) image files.

The browser vulnerability raised alarms in December after hackersdistributed a specially crafted WMF image through e-mail, instantmessaging links and websites. If the image was opened, it could allow ahacker to gain control over a victim's computer.

There are at least 600 websites that take advantage of the WMFvulnerability, Dunham said. Microsoft issued a patch for the problem inJanuary, but many consumer computers may not have applied the patch,leaving them unprotected.

Unpatched machines are particularly vulnerable. Merely visiting apage with the deckoutyourdeck.com banner ad causes a download of aTrojan horse program. Those who have installed the patch see a promptasking to download a file called "exp.wmf" when visiting a page withthe advertisement, Dunham said.

Once it starts to run, the Trojan in the banner ad causes infectedmachines to contact multiple websites and download, among otherunwanted programs, advertising software from PurityScan. The PurityScansoftware can cause unwanted pop-up windows to appear, and also tracks auser's online activity.

Adware can be very difficult to remove, even for technically savvy users.

"The problem is hackers are using a variety of exploits --especially WMF -- to illegally and silently install this [adware] onusers' computers," Dunham said.

MySpace has increasingly been targeted by hackers because of itspopularity. MySpace officials contacted in London Thursday afternoonhad no immediate comment. iDefense's Dunham was not sure whether thebanner advertisement has been taken down yet, but said that it couldhave been active for weeks.

Web sites that distribute adware are paid based on the number ofmachines that get infected with the software, and hackers have createdways to spread the adware without user consent, increasing theirpayments.

iDefense estimated the number of infections caused by thedeckoutyourdeck.com ad through a server in Turkey hosting the adware.The server appears to track the number of machines infected with theadware, and indicated that 1.07 million computers had downloaded theprogram, Dunham said.

A Whois search for deckoutyourdeck.com leads to a winding trail ofregistrants. Dunham said hackers frequently use false credentials whenregistering a domain name to cloud inquiries.