The biannual report, which is based on real-world data from millions of Windows machines worldwide that Microsoft scans and cleans with its products and services, also highlighted a nearly 8 percent decrease in overall vulnerability disclosures this year versus the second half of last year -- seemingly good news for secure software development initiatives, such as Microsoft's Secure Development Life Cycle.
New vulnerability disclosures for all software have been on a gradual decline for the past four years, according to Microsoft's data. There were around 2,500 new vulnerability disclosures in the first half of this year, versus 3,500 in the second half of 2006. "The caveat is that it's good that it's down, but those numbers are still really high, in the 2,500 to 3,000 range for a six-month period," says Jeff Jones, director of Trustworthy Computing at Microsoft.
Jones says a positive sign is that the number of users running Microsoft's Windows Update and Microsoft Update services have increased 75 percent during the past four years. "One of the fundamentals we promote is staying up-to-date," he says.
The U.S. hosts the most bot infections, with 2.2 million zombie machines, followed by Brazil with 550,000, and Spain with 382,000 bots. When it comes to the highest rate of bot infection, Korea was No. 1 with 14.6 bots cleaned per thousand Windows machines. Spain came in second with 12.4 bots per thousand machines, followed by Mexico with 11.4 bots cleaned per thousand computers.
"We are seeing botnets as the integration point for malware and the launchpad for cybercrime," Microsoft's Jones says. "We are seeing some good impact [from botnet takedowns], but equally there is still a high number of infections, so there's lots of work still to be done."
The surge in bots this year could also be due to Microsoft's more aggressive strategy to knock them down, says one security expert. Graham Titterington, principal analyst with Ovum, says he believes the numbers reflect Microsoft's focus on rooting and snuffing out botnets. "It's mainly due to Microsoft getting more aggressive in searching out botnets," Titterington says.
Microsoft flexed its botnet-battling muscles in February when it led an industry effort to kill the former Storm spamming botnet, which had been reinvented as Waledac. Microsoft, Shadowserver, the University of Washington, Symantec, and a group of researchers from Germany and Austria conducted a sneak attack highlighted by a federal court order that forced VeriSign to cut off 277 Internet ".com" domains that had been serving as the connections between the botnet's command and control servers and its around 60,000 to 80,000 bots.
A couple of weeks later, word got out that another botnet, Mariposa, was infiltrated and decapitated by law enforcement officials in Spain, as well as from the FBI, Panda Security, Defence Intelligence, and Georgia Tech. Mariposa was a massive global botnet with close to 13 million infected machines in more than 190 countries -- including those of half of all Fortune 1000 firms. The botnet harvested banking credentials, credit card information, account information from social networking sites and online email services, and other usernames and passwords.
The takedowns were unprecedented international efforts, but even the participants admitted they aren't necessarily long-term solutions. "Any progress we make helps with the overall problem ... when we chopped the head off Waledac, there was an immediate benefit and it was stopping spam off that," Microsoft's Jones says. "It's not perfect, but it's an effort worth doing."
Microsoft cleaned up nearly 30,000 Waledac bots in the second quarter of the year, a major drop from the 83,580 Waledac bots it cleaned in the first quarter.
While a botnet takedown results in an immediate reduction in spamming and other cybercrime, the lull typically lasts only until the bad guys regroup, relocate, or reinvent themselves with another botnet. The honeymoon is often over after a few months, Ovum's Titterington notes.
"The long-term solution is making the environment more secure and less prone to botnets: hardening the operating system, getting people to use better hygiene on the Net, installing patches, anti-malware, etc.," he says.
It's the next step -- cleaning up all of the bots -- that's the tricky part. "If we can figure out how to collectively get those machines cleaned up, it takes more tools away from the cybercriminals," Microsoft's Jones says.
Meanwhile, the most active botnet families in the first half of this year, in order, were Rimecud, a malware kit used in Mariposa, Alureon, Hamweq, Pushbot, IRCbot, Koobface, FlyAgent, Virut, Renocide, and Hupigon, according to the report.
Among the other key findings in the report was that stolen equipment is still the No. 1 cause of a security breach (30.6 percent of incidents), and infection rates for Windows 7 are the lowest of all Windows OSes, accounting for about 2.5 percent of infected machines.
The full Microsoft SIR version 9 is available for download here.
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