Recently I have been doing multiple installs of Virtualmin on OpenVZ and KVM systems. I have noticed that on KVM every single install that the "Index of" folder is viewable from the web via direct access to the servers IP address.
I have attached an image of what is seen when you go directly to the server IP.
This also happens with any virtual servers that you create.
This is not a problem to me as I am using this server for DNS bind only for nameservers but It is worth noting. If you need any info let me know and Ill get it for you.