After a decade of abuse, Autorun is finally being retired in older versions of Windows.

On Tuesday, Microsoft began pushing an update that changes the way Windows Server 2008 and earlier versions of the OS respond when USB thumb drives and other portable media are plugged in. Until now, those versions dutifully executed code embedded in autorun.inf files without first prompting the user. The default behavior provided a convenient way to propagate malware such as Conficker, which hijacked the feature to spread itself each time an infected drive was inserted.

Microsoft finally nixed Autorun in Windows 7, but until now, users of earlier versions had to muck about in the Windows registry or install a special fix it to turn it off. Adding the change to the official Windows Update mechanism means millions of users will turn it off automatically.

“We feel like now is the right time across the industry to be able to push this change out and have a pretty substantial impact on how malware spreads,” Jerry Bryant, group manager in Microsoft's Response Communications, told The Reg. “This is really something that will help to further protect the ecosystem.”

Bryant said the main reason Microsoft didn't retire Autorun sooner was the resistance from some partners who rely on the feature to install programs that accompany their hardware. Over the past few years technologies such as in the U3 functionality found on many thumb drives has provided alternatives.

The "Important, non-security update" was pumped into the pipeline on the same day Microsoft issued 12 security bulletins fixing 22 vulnerabilities in Windows, Office, Internet Explorer and IIS. Three of the bulletins are rated critical. Sans has a helpful breakdown here.

As we've pointed out before, the changes to Autorun still don't go far enough. CDs and DVDs by default still automatically execute code when inserted. Adam Shostack, a program manager for Microsoft's Trustworthy Computing group, said here that Microsoft has yet to see in-the-wild attacks that exploit Autorun on “shiny media.”

Weighing the minimal amount of convenience from Autorun against its potential for bad things to happen, we still think it's a bad idea, even for CDs and DVDs. Those who agree can turn it off entirely by following the instructions here. ®