[libvirt] security: the qemu agent command "guest-exec" may cause Insider Access

Peter Krempa pkrempa at redhat.com
Fri Aug 25 07:24:43 UTC 2017

On Fri, Aug 25, 2017 at 06:45:18 +0000, Zhangbo (Oscar) wrote:
> Hi all:
>      The Host Administrator is capable of running any exec in guests via the qemu-ga command "guest-exec", eg:
>         virsh qemu-agent-command test_guest '{"execute": "guest-exec", "arguments": {"path": "ifconfig", "arg": [ "eth1", "" ],"capture-output": true } }'
> {"return":{"pid":12425}}
>        virsh qemu-agent-command test_guest '{"execute": "guest-exec-status", "arguments": { "pid": 12425 } }'
> {"return":{"exitcode":0,"exited":true}}
>       The example above just change the guests' ip address, the Administrator may also change guests' user password, get sensitive information, etc. which causes Insider Access.
>       The Administrator also can use other commands such as " guest-file-open" that also cause Insider Access.
>       So, how to avoid this security problem, what's your suggestion?

You can use the "--blacklist" facility of qemu-ga to disable APIs you
don't want to support. Or don't run the guest agent at all.
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