Microsoft has recently issued updates for Windows XP and Vista which can help stop worms such as Conficker spreading via infected flash drives.  Windows 7 is already protected.

The updates modify the way AutoRun and AutoPlay work, to keep malware from silently installing on a victim’s PC.  Conficker and similar worms use a malicious “autorun.inf” file on USB storage devices connected to already-infected machines, which then spread to any other PC if the user connected the device to that second computer and picked the “Open folder to view files” option under “Install or run program” in the AutoPlay dialog.

The change to the AutoPlay dialog no longer let users run programs, except when the device is a nonremovable optical drive.  Instead, a flash drive connected to a Windows 7 system only opens a folder to show a list of files.

The updates are available for download and installation from Microsoft’s download site, and are strongly recommended.