The Windows 7 era has been fairly mild with regards to security. There have been holes to patch, such as a Zero-Day Server Message Block file-sharing protocol vulnerability in the operating system, but not the plague of problems that hit Microsoft in the past. And the security enhancements keep coming. Windows 7 extended BitLocker drive encryption support to removable storage devices. In the wake of the spread of the Conficker worm via USB drives, Microsoft said it was changing the way Windows 7 handles USB drives so they would not be able to automatically launch a program using the AutoRun function.