VMware's scripting API allows a malicious script on the host machine to execute programs, open URLs, and perform other privileged operations on any guest operating system open at the console, without requiring any credentials on the guest operating system. Furthermore, the script can execute programs even if you lock the desktop of the guest OS.
As opposed to pausing the VM, editing the virtual memory image and unpausing the VM? No scripting interface is needed. How about editing the virtual disk image and replacing one of the cron scripts with a shell-on-a-port? Rebooting the VM and going single user? If you control the VMware process, you control the guest. Fully and Completely.
Mark Burnett http://xato.net
Tim Newsham http://www.thenewsh.com/~newsham/