Microsoft has launched an update for the AutoRun feature. The company is now pushing the update to Windows Vista and Windows XP users automatically.

When Microsoft had first deployed the update on the 8th of February, it said the patch would be offered as an optional download. For retrieving it, users had to manually checkmark the “KB971029” update in the “Software, Optional” section of Windows Update in Windows XP or Windows Vista, which can be found under the option “Important.”

In Windows XP, users now see the AutoRun fix under the “High-priority updates” label, and the patch is pre-checked so that it downloads and installs without involving any user action. The “High-priority updates” section under the XP Windows Update is the exact location wherein security-related patches appear.

Both Conficker, an infection that spread a couple of years ago, and the worm Stuxnet, had used AutoRun and Flash drives to infect Windows-based PCs. To lump automatic implementation of files on a USB drive, Microsoft changed AutoRun’s behavior in Windows and first backported the modifications to Windows Vista and Windows XP in August 2009. When the update is in place, Flash drives inserted into a PC running Windows Vista or Windows XP not offering the choice to run programs, as the AutoRun extinction does not affect DVDs or CDs. Microsoft confirmed the update reset, and further said that it altered the delivery process for minimizing the user interaction required to install the updates on systems configured for automatic updating.

Microsoft also noted that the update breaks the functionality of some USB drives. Microsoft warned in a security advisory that users who install this update would no longer receive a set-up message that prompts them to install programs that are delivered by USB Flash drives, and they would have to manually install the software. To disable the update’s changes and revert to Windows XP and Windows Vista default settings, users can run the ‘Enable Autorun’ tool found on the support site of Microsoft.