Per the 5.1 security guide you should:
Limit informational messages from the virtual machine
to the VMX file to avoid filling the datastore and g 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.
I was always under the impression that the OS did not know it is virtualized. If it does know its virtualized how could it modify the vmx? Also anytime I edit the VMX I have to power the Machine down, so again how can bade code cause damge to the vmx. An example would be helpful