Version 7 of Microsoft's Security Intelligence Report (SIR) -- which drew its data from over 450 million Windows PCs worldwide from January to June 2009 -- found that worms are now the number two threat, behind Trojans, and up from the number five slot in the second half of 2008. "We're seeing a resurgence of worms: they've risen by 98.4 percent," says Jeff Williams, principal architect for Microsoft's Malware Protection Center. "This is due to Conficker and TaterF, a lesser known [worm] but almost as prevalent as Conficker."
And Trojans, including rogue antivirus, remain the most commonly found threat on infected machines. But rogue AV is also declining somewhat: Microsoft cleaned up 13.4 million computers with rogue AV in the first half of this year, down from 16.8 million in the second half of 2008, according to the report.
Meanwhile, the biggest surprise was that the total number of reported vulnerabilities in the industry decreased by nearly 30 percent from the second half of '08, with fewer than 2,500 new vulnerabilities disclosed in the first half of this year versus over 3,000 in the last half of last year.
"It's possible that the industry is getting better at writing software, but I wouldn't expect such a sharp decline," says Chenxi Wang, principal analyst for security and risk management at Forrester. "I think more likely this is a temporary decline. We'll have to wait and see whether this becomes a long-term trend -- I doubt it."
The decrease in rogue security software was promising, but it's still a major threat, says Microsoft's Williams. He says the reduction is likely due to enforcement efforts by Microsoft, and the Federal Trade Commission going after the culprits who distribute the software.
"It's a software that preys on fear and the fact that many users will click on pop-ups, often just to make them go away, [which is] not a good practice at all," says Donald Retallack, research vice president for systems management and security at Directions on Microsoft.
Microsoft cleaned up the TaterF worm from over 700,000 machines the first day it was added to the MSRT, and it has increased 156 percent, from 2 million infected machines in the second half of last year to 4.9 million this year.
TaterF, which steals online gaming login credentials, has become a big problem in enterprises. Like Conficker, it spreads via Microsoft's Autorun feature, for instance. "It has hit enterprises fairly hard because of the proximity of networks in that environment," Microsoft's Williams says. "It spreads through drives ... People play games at home, where they don't necessarily have enterprise protections. Then they shuttle information or files or programs of their own on removable media, like a USB key," which then infects their work machines as well, he says.
"TaterF has a malicious payload from the get-go," he says. Conficker, meanwhile, was still ahead of TaterF this year so far, with 5.2 million infected machines.
Microsoft also reported that Trojan downloaders have dropped -- namely Zlob, which at its peak had infected 21 million machines, but as of the first half of '09, was found on only 2.3 million machines. Williams says that's possibly due to Zlob's creators abandoning that model and going to shellcode exploits and scripting attacks, for instance.
Version 7 of Microsoft's SIR, which gathered data from Microsoft's Bing, Live OneCare, Defender, Forefront Online Protection for Exchange, and Microsoft's Malicious Software Removal Tool (MSRT), also found that Windows Vista SP1's infection rate was nearly 62 percent less than that of Windows XP SP3.
And the next version of the report will include data from the company's new free antivirus product, Microsoft Security Essentials (MSE), according to Microsoft's Williams.
"It will be interesting to see the next version of this report since Microsoft will have data from its free Security Essentials product as well as some information about Windows 7," Directions On Microsoft's Retallack says. "In the meantime, Microsoft continues to build a huge database of vulnerability information gleaned from many sources and from hundreds of millions of computers worldwide. That can only help improve security products such as the Forefront line."
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