Just a quick comment about something I noticed while rebuilding a test VM on my Mac. There is a long lead up to this, so bear with me…
I use VirtualBox on three different host operating systems.
Mac : My main desktop is a Mac, so most of my tests are done using Oracle 12c on Oracle Linux 6 or 7, running under VirtualBox. Most of the VMs I use are quite old, but I keep the DB and OS patched, and you know I religiously update VirtualBox. The point is, I rarely do fresh installations on Mac.