AutoRun is a Windows feature that allows files or programs to immediately run as soon as a removable media device, such as a USB stick or CD-ROM, is connected to a computer.AutoRun feature could allow malicious code to spread. One of the vectors by which the infectious Conficker, or Downadup, worm propagates is through pen drives / other removable storage medias
Microsoft has fixed a problem that prevents users from selectively disabling AutoRun features in an effort to stop the Conficker worm from spreading.
Microsoft said it recommends all customers to install the update, which affects all supported Windows versions.
Install this update to restrict AutoRun entries in the AutoPlay dialog to only CD and DVD drives. After you install this item, you may have to restart your computer.