I'm with Milas. I'd recommend one other real-time protection if you're going to use Windows Defender. If not real-time, at least get a few on-demand scanners like Zemana, Emsisoft, or Malwarebytes.
Using NAT adapter in network settings of a VM + no shared folders between guest and host (and if you are really paranoid use VPN) should be enough.These are the default settings in VirtualBox anyways, so dont change anything without consulting MT guides. The static malware at the hub I am sure will not affect any firmware or BIOS(bootkits) but having another system( old will do) and another non related connection is preferable.