Virtual Hard Disk (.vhd file) contents may be accessed by all users after you mount the file as a loopback device in Windows Server 2008

Consider the following scenario. You mount a Virtual Machine hard disk file (.vhd file) as a loopback device in Windows Server 2008. The .vhd file is now available as a virtual hard disk. In this scenario, users may access the virtual machine, and they can read from or write to the virtual hard disk.

This issue occurs if you mount a .vhd file as loopback device by using the Hyper-V Windows Management Instrumentation (WMI) APIs.

To enforce the security of the contents of a .vhd file that is mounted as a loopback device, use one of the following methods:

• Configure NTFS file system permissions on files and folders in the mounted .vhd file.
• Use a separate server to which virtual machine users do not have access.

For more information about Hyper-V, visit the following Microsoft Web site: