There were 1.3 million fewer infections for Windows Vista and XP systems from mid-February to mid-May compared to the three prior months, says Microsoft (NASDAQ: MSFT) in a TechNet blog entry. This follows an update released on February 8 that prevents AutoPlay from being enabled automatically (it still kicks in on CD and DVD media), which is now being credited for the improvement.

AutoRun has been a real and persistent threat for the longest time, and is a vector that works especially well against novice computer users. Microsoft's Holly Stewart writes: "Abusing Autorun was only one trick up their collective sleeve. However, judging by the numbers in our data, it was a lucrative one." Windows 7 already has AutoRun locked down, so it's not affected by the February AutoPlay update. 

The statistics are gleaned from computers running MMPC (Microsoft Malware Protection Center) products, which includes the Microsoft Malicious Software Removal Tool (MSRT). This means that the numbers reflect malware that has been detected and blocked, and are not necessarily related to actual infections. Regardless, it's a good way to keep track of trends.

Finally, more good news: The number of infections across all operating systems and service packs has declined by 68% from 2010.

For more:
- check out this article at CNET News
- check out this article at PCWorld
- check out this article at TechNet

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