Microsoft's security team plans to retire a much-abused feature in its Windows operating system that uses flash drives and other removable media to spread malware.

Beginning with Release Candidate 1 of Windows 7, the operating system will no longer display AutoRun when most removable media is connected. Up to now, the feature has automatically opened a window each time a drive is connected that presents a list of tasks the user can instruct Windows to carry out. Malware purveyors have long manipulated the feature to display options that say things like "open folder to view files" but install malware when clicked instead.

"With these changes, if you insert a USB flash drive that has photos and has been infected by malware, you can be confident that the tasks displayed are all from software already on your computer," Arik Cohen, a program manager on the Microsoft's core user experience team writes here. The changes eventually will be added to Vista and XP.

During the second half of 2008, malware that abused AutoRun accounted for almost 18 percent of infections, the biggest single malware category, according to a Security Intelligence Report Microsoft released earlier this month. Indeed, the AutoRun ruse is one of the secrets behind the rapid spread of the Conficker worm.

The move is definitely a step in the direction, but it's by no means perfect. A fair number of today's flash drives, including those made by U3, will continue to evoke an AutoRun popup window upon connecting to Windows. That's because Windows sees the devices as a CD or DVD drive and Microsoft will continue to display AutoRun when such optical drives are attached. This is a hole big enough to drive a truck through, and you can be sure malware distributors will do just that.

Microsoft says the change is designed to find middle ground between security and usability of removable media. Perhaps so, but it's worth remembering that Windows is the only operating system that has an AutoRun feature - and for good reason. Even Macs - with the mantra "it just works" - have eschewed the added convenience of AutoRun.

So thanks and congratulations, Microsoft, but we'll continue to disable AutoRun altogether. Instructions are here. ®