The guest operating system that runs in the virtual machine is subject to the same security risks as a physical system. Secure virtual machines as you would secure physical machines. Limit Informational Messages from Virtual Machines to VMX FilesLimit informational messages from the virtual machine to the VMX file to avoid filling the datastore and causing a Denial of Service (DoS). A Denial of Service can occur when you do not control the size of a virtual machine's VMX file and the amount of information exceeds the datastore's capacity. Prevent Virtual Disk ShrinkingNonadministrative users in the guest operating system are able to shrink virtual disks. Shrinking a virtual disk reclaims the disk's unused space. However, if you shrink a virtual disk repeatedly, the disk can become unavailable and cause a denial of service. To prevent this, disable the ability to shrink virtual disks. Virtual Machine Security Best PracticesFollowing virtual machine security best practices helps ensure the integrity of your vSphere deployment.