oss-sec mailing list archives

Re: CVE Request: Ansible not caching SSH host keys


From: Kurt Seifried <kseifried () redhat com>
Date: Tue, 02 Jul 2013 14:52:48 -0600

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On 06/30/2013 10:45 PM, Michael Samuel wrote:
http://www.ansibleworks.com/

Problem: Default configuration does not cache SSH host keys,
effectively disabling host key checking

Note - do not credit me for finding this, I'm just the only person 
indignant enough to request a CVE

A colleague found this bug, only to notice that it was logged by
somebody else (antong on github), and rejected: 
https://github.com/ansible/ansible/issues/857

This can be fixed by calling ssh.load_system_host_keys() after line
78 of 
https://github.com/ansible/ansible/blob/496f06c3c90cfd89802622c640480328436746c6/lib/ansible/runner/connection_plugins/paramiko_ssh.py

 While it is possible to call the SSH command instead of using
paramiko, this isn't the default and the ramifications of not
checking host keys aren't advertised to users.  A more reasonable
approach would be to document how to un-cache a host key should it
change.

Regards, Michael

Please use CVE-2013-2233 for this issue. After some thought I think it
qualifies, host key caching is def. a security feature designed to
prevent mitm (if you constantly hammer the user to check/accept keys
at some point they'll just go "sure whatever, they must have changed
something on the remote end).

- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
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