• Back to all articles

Ubuntu: New Puppet packages fix security vulnerabilities

It was discovered that Puppet incorrectly handled the non-default “certdnsnames” option when generating certificates. If this setting was added to puppet.conf, the puppet master’s DNS alt names were added to the X.509 Subject Alternative Name field of all certificates, not just the puppet master’s certificate. An attacker that has an incorrect agent certificate in his possession can use it to impersonate the puppet master in a man-in-the-middle attack. Updated packages are available from security.ubuntu.com.

==========================================================================
Ubuntu Security Notice USN-1238-1
October 24, 2011

puppet vulnerability
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 11.10
- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS

Summary:

The Puppet master server could be impersonated in certain configurations.

Software Description:
- puppet: Centralized configuration management

Details:

It was discovered that Puppet incorrectly handled the non-default
"certdnsnames" option when generating certificates. If this setting was
added to puppet.conf, the puppet master’s DNS alt names were added to the
X.509 Subject Alternative Name field of all certificates, not just the
puppet master’s certificate. An attacker that has an incorrect agent
certificate in his possession can use it to impersonate the puppet master
in a man-in-the-middle attack.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 11.10:
 puppet-common                   2.7.1-1ubuntu3.2

Ubuntu 11.04:
 puppet-common                   2.6.4-2ubuntu2.5

Ubuntu 10.10:
 puppet-common                   2.6.1-0ubuntu2.4

Ubuntu 10.04 LTS:
 puppet-common                   0.25.4-2ubuntu6.5

In general, a standard system update will make all the necessary changes.

If your puppet master's puppet.conf file has ever contained the
"certdnsnames" setting, you must reissue your site certificates, or apply
another mitigation technique. Please see the upstream advisory for more
information:

http://puppetlabs.com/security/cve/cve-2011-3872/

References:
 http://www.ubuntu.com/usn/usn-1238-1
 CVE-2011-3872

Package Information:
 https://launchpad.net/ubuntu/+source/puppet/2.7.1-1ubuntu3.2
 https://launchpad.net/ubuntu/+source/puppet/2.6.4-2ubuntu2.5
 https://launchpad.net/ubuntu/+source/puppet/2.6.1-0ubuntu2.4
 https://launchpad.net/ubuntu/+source/puppet/0.25.4-2ubuntu6.5