7.5 - RHSA-2012:1379

Problem Description:

Updated openstack-swift packages that fix one security issue are now available for Red Hat OpenStack Essex.

The Red Hat Security Response Team has rated this update as having important security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

2. Relevant releases/architectures:

RHOS Essex Release - noarch

3. Description:

OpenStack Swift (http://swift.openstack.org) is a highly available, distributed, eventually consistent object/blob store.

It was found that OpenStack Swift used the Python pickle module in an insecure way to serialize and deserialize data from memcached. As memcached does not have authentication, an attacker on the local network, or possibly an unprivileged user in a virtual machine hosted on OpenStack, could use this flaw to inject specially-crafted data that would lead to arbitrary code execution. (CVE-2012-4406)

Red Hat would like to thank Sebastian Krahmer of the SUSE Security Team for reporting this issue.

Note: The fix for CVE-2012-4406 is not enabled by default, and requires manual action on the affected Proxy nodes. This update adds a "memcache_serialization_support" option. It is configured in "/etc/swift/proxy-server.conf" and is set to "0" by default. This default setting is vulnerable to CVE-2012-4406.

To enable the fix, this option must be changed; however, the required changes can have a temporary, large performance impact. The following instructions aim to minimize performance issues:

1) Install the updated openstack-swift packages.

2) In "/etc/swift/proxy-server.conf", set the "memcache_serialization_support" option in the memcache/[filter:cache] section to "1". (The default value, "0", leaves you vulnerable to CVE-2012-4406.) When set to "1", the JSON (JavaScript Object Notation) format is used but pickle is still supported. This configuration is still vulnerable, but new data will be stored in JSON format.

3) After setting the option to "1", run "service openstack-swift-proxy restart".

4) After 24 hours, set the "memcache_serialization_support" option in "/etc/swift/proxy-server.conf" to "2". "2" is the secure option: only JSON is used.

5) After setting the option to "2", run "service openstack-swift-proxy restart".

If "memcache_serialization_support" is set directly from "0" to "2", all data in memcached will be flushed and re-created. This can lead to a temporary, large performance impact.

All users of openstack-swift are advised to upgrade to these updated packages, which correct this issue.

4. Solution:

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258

5. Bugs fixed (http://bugzilla.redhat.com/):

854757 - CVE-2012-4406 Openstack-Swift: insecure use of python pickle()