virtualbox.org

When guest additions are installed, the guest gets access to the hosts built-in microphone. I do not want this, because if the VM gets compromised, someone can listen.

Is it possible to disable this feature? For example with some undocumented "VBoxManage setextradata vmname VBoxInternal/Devices/xxx 0" like command?

You can disable the entire audio interface easily enough in the VM settings. There is no documented way to disable just a part of it.

Thank you!

I want to have audio. Use case for example: Using Flash in a VM. Flash has a history of vulnerabilities and risks the VM getting infected. I want to watch videos but in case of compromise, not anyone being able to listen to my host's microphone.

Posted a feature request.

Can't you just disable or mute the mic in the VM itself using the VM's OS's audio controls?

Rootman wrote:Can't you just disable or mute the mic in the VM itself using the VM's OS's audio controls?

Once the virtual machine is compromised, this can be reversed. This setting has to be made on the host, not in the VM.

bmn wrote:

Rootman wrote:Can't you just disable or mute the mic in the VM itself using the VM's OS's audio controls?

Once the virtual machine is compromised, this can be reversed. This setting has to be made on the host, not in the VM.

OK, so how is the host more safe from compromise than the guest? Are they on separate subnets and the guest a honey-pot or something?

You wrote.

Rootman wrote:Can't you just disable or mute the mic in the VM itself using the VM's OS's audio controls?

Did you want to write "Can't you just disable or mute the mic in the VM itself using the host OS's audio controls?" by chance?

Rootman wrote:

bmn wrote:

Rootman wrote:Can't you just disable or mute the mic in the VM itself using the VM's OS's audio controls?

Once the virtual machine is compromised, this can be reversed. This setting has to be made on the host, not in the VM.

OK, so how is the host more safe from compromise than the guest? Are they on separate subnets and the guest a honey-pot or something?

Because less safe things (flash) can be run inside a virtual machine and therefore don't have access to stuff on the host. You're right, not getting the VM compromised in the first place would be even better. When the VM is compromised, the attacker can try to break out of the VM. That's probably not impossible, but requires another attack and therefore highers the bar of required effort to compromise the host. I don't think it's a perfectly secure solution. It just highers the bar. When we lock our doors, those safety isn't perfect by any means. Anyhow, its highers the bar to a level, that not every day someone breaks the lock, although the lock isn't perfect. But that's drifting off topic.

bmn wrote:You wrote.

Did you want to write "Can't you just disable or mute the mic in the VM itself using the host OS's audio controls?" by chance?

No, just mute the mic using the guests audio controls, perhaps even disable the MIC devise itself via the guests device manager? Anything that is compromised under the guest should be shut off until they reactivate the MIC itself or use the audio controls to unmute it. Not perfect but doable.

Other wise if you disable the MIC in the HOST OS it should also disable it the guests - however you indicated that you didn't want to do this. Other wise perhaps attach an external mic with a physical MUTE or ON / OFF switch and switch it off.

A suggestion based on my own experience, in the host audio settings change it to "line in" instead of internal. Then just do not plug in a microphone. I am attempting to use a microphone on my windows guest using a MAC host. When I change the host to "line in" even plugging in my microphone doesn't work, and it isn't picking up my internal microphone either.