Any enabled or connected device represents a potential attack channel. Users and processes without privileges on a virtual machine can connect or disconnect hardware devices, such as network adapters and CD-ROM drives. Attackers can use this capability to breach virtual machine security. Removing unnecessary hardware devices can help prevent attacks.

An attacker with access to a virtual machine can connect a disconnected hardware device and access sensitive information on the media left in the drive, or disconnect a network adapter to isolate the virtual machine from its network, resulting in a denial of service.
  • Ensure that unauthorized devices are not connected and remove any unneeded or unused hardware devices.
  • Disable unnecessary virtual devices from within a virtual machine.
  • Ensure that no device is connected to a virtual machine if it is not required. Serial and parallel ports are rarely used for virtual machines in a data center, and CD/DVD drives are usually connected only temporarily during software installation.


  1. Log into a vCenter Server system using the vSphere Web Client.
  2. Right-click the virtual machine and click Edit Settings.
  3. Check each hardware device and ensure that you want it connected.
    Include checks for the following devices:
    • Floppy drives
    • Serial ports
    • Parallel ports
    • USB controllers
    • CD-ROM drives