Potential Denial of Service in Horizon login
---

### Summary ###
Horizon uses the Python based Django web framework. Older versions of
this framework allow an unauthorized user to fill up the session store
database causing a Horizon denial of service. A fix for Django is
available but works only with Kilo and later versions of Horizon.

### Affected Services / Software ###
Horizon, Django, Essex, Folsom, Grizzly, Havana, Icehouse, Juno

### Discussion ###
Django will record the session ID of web requests even when the request
is from an unauthorized user. This allows an attacker to populate the
session store database with invalid session information, potentially
causing a denial of service condition by filling the database with
useless session information.

### Recommended Actions ###
The Django developers have released a fix for this issue which is
included in software versions 1.4.21, 1.7.9 and 1.8.3. Horizon
administrators should ensure that they are using an up to date version
of Django to avoid being affected by this vulnerability.

Versions of Horizon prior to Kilo cannot run with the fixed version of
Django, and may require updating to a newer version of OpenStack.
Administrators can test if their deployment is affected by attempting to
inject invalid sessions into the session store database using the
following script and then querying the session store database to check
if multiple 'aaaaa' session ID's were recorded.

---- begin example ----
for i in {1..100}
do
  curl -b "sessionid=aaaaa;" http://HORIZON__IP/auth/login/ &> /dev/null
done
---- end example ----

If possible, affected users should upgrade to the Kilo or newer release
of Horizon, allowing them to use the fixed version of Django.

### Contacts / References ###
Author: Robert Clark, IBM
This OSSN : https://wiki.openstack.org/wiki/OSSN/OSSN-0054
Django fix : https://www.djangoproject.com/weblog/2015/jul/08/security-releases/
Django CVE : CVE-2015-5143
Original LaunchPad Bug : https://bugs.launchpad.net/horizon/+bug/1457551
OpenStack Security ML : openstack-security@lists.openstack.org
OpenStack Security Group : https://launchpad.net/~openstack-ossg