Virtualbox: run vboxmanage on windows host via SSH?

I'm running virtualbox 4.3.16 on a Windows 7 64bit host with a few Linux guests.

I need to be able to issue poweroff commands from one guest to another, but the vboxmanage command isn't working when run via cygwin's SSH server.

vboxmanage works as expected when run in a cygwin shell on the host, but via SSH vboxmanage list vms is not giving any output, and VMs cannot be accessed.

Here's what I'm getting when I try to shut down one VM over SSH:

$ vboxmanage --nologo controlvm "rsfe1" poweroffvboxmanage.exe: error: Could not find a registered machine named 'rsfe1'vboxmanage.exe: error: Details: code VBOX_E_OBJECT_NOT_FOUND (0x80bb0001), component VirtualBox, interface IVirtualBox, callee IUnknownvboxmanage.exe: error: Context: "FindMachine(Bstr(a->argv[0]).raw(), machine.asOutParam())" at line 95 of file VBoxManageControlVM.cpp

Trying to "attach" the VM to the sshd account doesn't work either:

$ vboxmanage registervm "d:\virtual machines\rsfe1\rsfe1.vbox"vboxmanage.exe: error: A differencing image of snapshot {10077c46-d5cf-4402-88c0-f0458dd07f74} could not be found. Could not find an open hard disk with UUID {9404b00e-7b04-460f-8a62-6495885744de}vboxmanage.exe: error: Details: code E_FAIL (0x80004005), component SnapshotMachine, interface IMachine, callee IUnknownvboxmanage.exe: error: Context: "OpenMachine(Bstr(a->argv[0]).raw(), machine.asOutParam())" at line 88 of file VBoxManageMisc.cpp

All of the VMs were created under my regular user account myuser. I am also authenticating as myuser via SSH.

I guess the problem is that the cygwin SSHd runs as a privileged user cyg_server and something does not work right on login when the session is transferred to myuser.

I have tried running the cygwin SSHd service as myuser but the service requires more privileges than the account has, it seems, and doesn't run.

Is there any solution for this? Any possible environment variable manipulation?