virtualbox.org

I have a host computer with OSX. The host is a public computer that people can sign into with their credentials. The users are highly restricted in their access on the OSX side, and have a high level of trust on the network. Now I have virtualbox installed on that computer and user can access it and load their own .vdi files. So the user may have a VM with root ability, so I need to prevent them from accessing the network. How can I disable a user being able to change the network settings on the host side without disabling either USB sharing or memory allocation settings.

Thank you,

Mat