Pickled data in Glance database enables remote code execution

[Brian Waldon]

Glance uses pickled python objects for the storage of image location metadata in its SQL database backend [1]. In the event that the database server running beneath Glance is compromised, the usage of pickle will allow an attacker to execute untrusted code remotely and further compromise the cloud [2] [3].

[1] https://github.com/openstack/glance/blob/master/glance/db/sqlalchemy/models.py#L157
[2] See warning at the top of the pickle module doc: http://docs.python.org/2/library/pickle.html
[3] http://blog.nelhage.com/2011/03/exploiting-pickle/

[Thierry Carrez (ttx)]

I'd say this could be valid for OSSA because you escalate from DB compromise (DoS, data exploitation) to remote code execution with the glance user rights...

[Brian Waldon (bcwaldon)]

@thierry - totally agree. I don't have an example exploit, but thinking through the problem this does seem pretty terrible. Let's see what the openstack vuln mgmt team thinks...

[Mark Washenberger (markwash)]

Ack, good point. . .

[Jeremy Stanley (fungi)]

Even just from the perspective of separating operational roles, this means that someone who may already have authorization to write to the glance DB (for example to perform database maintenance) can in turn take direct control of any glance server. So yes, I would consider this a vulnerability worthy of an official announcement.

[Thierry Carrez (ttx)]

This might be tricky to fix while maintaining backward compatibility. Any taker for a patch ?

[Mark Washenberger (markwash)]

I'm not really sure this issue needs to be locked away.

This schema change was introduced during the havana dev cycle, so I do not expect it has been widely used as of yet.

And, of course, it is very easy to find in the current code that PickleTypes are being used--so the bug is not particularly obscure.

If it should be locked, how can I add permissions for certain contributors to view this bug?

[Thierry Carrez (ttx)]

If it's havana-only, then I think we don't need to release an OSSA for it, as havana is not security-supported yet. So I think we can open. Let me doublecheck with Jeremy and we'll get back to you.

[Jeremy Stanley (fungi)]

Ahh, yes, I would consider this a security vulnerability in unreleased software, fixed prior to official release. Given the class of vulneravility and limited potential points of exposure, coupled with the fact that we don't currently encourage continuous-deployment or milestone snapshots for production use cases, It's probably not necessary to issue an OSSA. CVEs are often enough assigned to pre-release/beta software versions if they're in wide use (where defining wide is left as an exercise for the reader), but I'd leave it up to the security group to decide whether they want to pursue a CVE assignment for it once the bug is opened up.

[Mark Washenberger (markwash)]

At this point jbresnah is in pursuit of the issue.

I think it might make sense to avoid actually unpickling the data during the migration to a different storage format, but I'm curious if any of the followers here might encounter problems with such a scheme?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/45335

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/45335
Committed: http://github.com/openstack/glance/commit/60ab0c8c564af989882f0ea2609019ea7206e2b3
Submitter: Jenkins
Branch: master

commit 60ab0c8c564af989882f0ea2609019ea7206e2b3
Author: John Bresnahan <email address hidden>
Date: Thu Sep 5 11:07:29 2013 -1000

    Convert location meta data from pickle to string.

    This patch fixes a potential security issue.
    Fixes bug: 1213241

    Change-Id: I6414d16ec72f26ceabbaf1364ad737f19f18381e