[Sporktacular]

This is not longer the case.

But another way around is the way VMWare Fusion let you set up networking in Bridged mode. Any traffic from the VM went through without a peep from Little Snitch running on the host. No reason malware couldn't be designed in the same way.

[jasomill]

VMware Fusion isn't sandboxed and installs daemons running as root (which requires Gatekeeper approval or bypass to run, followed by an admin password to install the daemons).

AFAIK, XProtect is the only remaining line of defense against malware installed in this way.

[Sporktacular]

So, Little Snitch helps unless your adversary is either really good at what they do or really rich. Maybe nothing can be done in those cases, but I'd like to see the limitations of such software placed on the box.