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", "192.168.0.99" ],"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?

>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", "192.168.0.99" ],"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. This works if the qemu-agent inside the guest is installed by us cloud provider. But if the guest is installed all by the cloud tenant himself, he may not know to add "--blacklist" by default, and doesn't notice that his OS is opposed to host attackers. How to solve this problem? It seems that we have to mitigate the treat on the host side?

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On Fri, Aug 25, 2017 at 08:52:16 +0000, Zhangbo (Oscar) wrote: > >On Fri, Aug 25, 2017 at 06:45:18 +0000, Zhangbo (Oscar) wrote: [...] > >> 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. > > This works if the qemu-agent inside the guest is installed by us cloud provider. But if the guest > is installed all by the cloud tenant himself, he may not know to add "--blacklist" by default, and > doesn't notice that his OS is opposed to host attackers. How to solve this problem? It seems that > we have to mitigate the treat on the host side? That premise is silly. Adding protection from the host on the host side does not make sense, since the host admin can always change it. You can avoid adding the guest agent channel though completely. On the guest, you can e.g. not install the guest agent. If you don't trust the host, don't use it. There's no protection from reading the memory or disk images currently. See [1]. Note that even without the API, root can access all the stuff.

[1]: http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainMemoryPeek

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", "192.168.0.99" ],"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? Thanks!

Best Regrads Oscar -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list

>On Fri, Aug 25, 2017 at 06:45:18AM +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", "192.168.0.99" ],"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? >> Thanks! >> > >What's your setup that this, in particular, is your concern? Do you >have everything encrypted by keys that are not reachable for the host >administrator? How are those saved? For example, how do you guard >against the host administrator killing the domain? Or mounting the disk Killing the domain is acceptable somehow at some degree, but leaking sensitive information, for example, trade secret, is horrible. We most concern is to protect that information by (maybe)disabling "guest-exec" guest commands etc.

Another concern, as mentioned in another mail, is that, if the cloud tenant himself installed the guest agent, and doesn't know the "adding --blacklist" issue, that guest is in danger. >of the domain, doing whatever they want to with it and starting it back? >Or million other things that come to mind. Not trusting the host >administrator is kinda (well, precisely) like not trusting root on *NIX >machine. > >Martin > >P.S.: Maybe more aluminium could help, but I haven't tried yet. > >>Best Regrads >>Oscar >> >>-- >>libvir-list mailing list >>libvir-list(a)redhat.com >>https://www.redhat.com/mailman/listinfo/libvir-list

> >Host can read all of the guest's memory or mount the image and modify >the guest agent. Or even add their own communication program that can >do anything. > I get your point now! :) Thanks a lot!! Further more, kvm seems not as secure as xen, because xen isolates dom0 and domU well, The administrator on dom0 couldn't access many things belonged to domUs. How to solve such problem in kvm? Any scheme?

On Fri, Aug 25, 2017 at 10:29:03AM +0000, Zhangbo (Oscar) wrote: >> >> Host can read all of the guest's memory or mount the image and modify >> the guest agent. Or even add their own communication program that can >> do anything. >> > > I get your point now! :) Thanks a lot!! > > Further more, kvm seems not as secure as xen, because xen isolates > dom0 and domU well, > The administrator on dom0 couldn't access many things belonged to domUs. > How to solve such problem in kvm? Any scheme? I don't know xen much, but maybe AMD SEV or everything-signed-by TPM would help...