VASTO is, or better was, a set of metasploit modules targeting virtualization platform.
It was presented at BlackHat in 2010 as the result of some of my research and pentesting activity.
It never made it to upstream, mostly because of my awful coding of the time and lack of interest in porting, but I do requests to re-release it from time to time, so I figured it's worth having it committed somewhere.
I don't really expect any of these attacks to work anymore against their targets, nor I expect them to run on any modern version of Metasploit. I don't really plan to work on this topic in the foreseeable future, though I still find it fascinating.