Top two threats both exploit the Windows Autorun feature, BitDefender study says

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When something works, hackers keep doing it. And as a vehicle for delivering malware, Microsoft's Autorun.INF utility is still working just fine, according to researchers at BitDefender.

In a study issued earlier this week, BitDefender reported that the top two malware offenders during the first six months of 2010 -- Trojan.AutorunINF.Gen and Win32.Worm.Downadup.Gen -- both exploit Autorun.INF.

Trojan.AutorunINF.Gen alone accounted for 11 percent of all the malware infections detected by BitDefender in the first half, according to the report.

"The autorun technique is massively used by worm writers as an alternate method of spreading their creations via mapped network drives or removable media," BitDefender says.

Initially designed to simplify the installation of applications located on removable media, the Windows Autorun feature has been used large scale as a means of automatically executing malware as soon as an infected USB drive or an external storage device has been plugged in, the report states. Unlike legitimate autorun.inf files, those used by miscellaneous malware are usually obfuscated, the researchers say.

"Before the arrival of the second service pack for Vista, Windows-based operating systems would follow any autorun.inf file instructions and blindly execute any binary file the autorun file pointed to," the report says. "Because of the risk the users were exposed to, Microsoft subsequently deactivated the autorun feature for all the removable devices except for the drives of type DRIVE_CDROM4."

MBR worms made a comeback in early 2010, with upgraded viral mechanisms, BitDefender states. Late January saw the emergence of Win32.Worm.Zimuse.A, a deadly combination of virus, rootkit, and worm.

Regionally, China and Russia are the world's top malware distributors, the report says. "During the last six months, China [31 percent] has been the most active country in terms of malware propagation, followed by the Russian Federation [22 percent]. Both countries are known for their lax legislation regarding cybercrime, as well as for the plethora of 'bulletproof hosting' companies," such as the Russian Business Network, which has been officially terminated but remains extremely active in practice, the researchers say.

PayPal remains the top phishing target in the world, acting as the subject for 53 percent of attacks, BitDefender says. PayPal's parent, eBay, finished second with 16 percent.

Spam continues to be a problem for most companies, according to BitDefender. Most spam messages are used to sell pharmaceuticals -- in fact, medicine-related spam jumped from 50 percent to 66 percent in the first half, according to the report.

While Web-borne malware remains strong, cybercriminals are moving more toward Web 2.0 exploits, focusing on social networks, such as Facebook and Twitter, while also expanding their attacks on instant messaging systems, the researchers say.

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About the Author(s)

Tim Wilson, Editor in Chief, Dark Reading


Tim Wilson is Editor in Chief and co-founder of Dark, UBM Tech's online community for information security professionals. He is responsible for managing the site, assigning and editing content, and writing breaking news stories. Wilson has been recognized as one of the top cyber security journalists in the US in voting among his peers, conducted by the SANS Institute. In 2011 he was named one of the 50 Most Powerful Voices in Security by SYS-CON Media.

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