The top threat in enterprise environments during the first half of the year was the Conficker worm, Microsoft says in its Security Intelligence Report (SIRv7), which covers the first six months of 2009.
According to SIRv7, the number of worm infections in enterprise environments -- those running Forefront Client Security -- doubled from the last half of 2008 through the first half of 2009. During this period, worms rose from fifth most commonly encountered threat category to the second.
Among home PC users -- those protected by Windows Live One Care -- worms are not nearly as much of a concern. Home users saw mainly malware in the Trojan Downloaders & Droppers category and in the Miscellaneous Trojans category.
The most commonly encountered threat category for businesses was Miscellaneous Trojans, which includes rogue security software.
While rogue security software continues to present a risk, Microsoft says that 20% fewer customers were affected by it in the first half of this year compared to the second half of last year.
Microsoft's report also documents increased detection of password stealing and monitoring tools, which the report attributes to increasing malware attacks on online gamers.
And on a related note, the amount of phishing detected by Microsoft was nearly four times higher in May and June 2009 than it was in the ten preceding months, the result of a campaign targeting social sites.
The SIRv7 report documents some of Microsoft's success in battling malware creators.
The report says that because of Microsoft's SmartScreen Filter, which offers phishing and malware protection in Internet Explorer 8, the amount of Miscellaneous Potentially Unwanted Software detected rose from 35% in the second half of 2008 to 44% in the first half of 2009.
During the same period, Microsoft saw the percentage of computers cleansed of malware in this category drop from 22.8% to 14.9%.
Based on these statistics, report concludes that Microsoft's security measures are stopping malware before it gets downloaded.
Along similar lines, Microsoft's self-assessment of vulnerabilities in its operating systems suggests that the company's commitment to security is paying off.
In the first six months of the year, the infection rate for Windows Vista was 61.9% less than it was for Windows XP SP3 and the infection rate for Windows Server 2008 RTM was 52.6% less than it was for Windows Server 2003 SP2, the report says.
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