Open Stack

[Draft] Please review and add content as you feel appropriate

Restarting memcached loses revoked token list
----

### Summary ###
When a cloud is deployed using Memcache as a backend for Keystone tokens
there is a security concern that restarting Memcached will loose the
list of revoked tokens, potentially allowing bad tokens / users to
access the system after they had been revoked.


### Affected Services / Software ###
Keystone, Memcache

### Discussion ###
There might be ways to mitigate in the future, such as running memcached
on multiple machines to ensure redundancy should the Keystone server
fail. In a clustered environment, it will only be an issue if all of the
memcached machines shutdown.

Memcachedb might also be a potential way to mitigate.
http://memcachedb.org/

NOTE: Some deployments may intentionally flush Memcached in response to
https://bugs.launchpad.net/ossn/+bug/1179955 - please exercise caution
when considering how to approach this problem.

### Recommended Actions ###
This is a fundamental problem with using in-memory ephemeral storage for
security information. If your deployment has strong security
requirements or a reliance on up-to-date revoked token information we
suggest you consider using an on-disk DB such as MySQL / PostgreSQL or
perhaps look into Memcachedb.

### Contacts / References ###
This OSSN : https://bugs.launchpad.net/ossn/+bug/1182920
OpenStack Security ML : openstack-security at lists.openstack.org
OpenStack Security Group : https://launchpad.net/~openstack-ossg

Robert Clark
Security Architect
HP Cloud Services


-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 6187 bytes
Desc: not available
URL: <http://lists.openstack.org/pipermail/openstack-security/attachments/20130807/5b22078e/attachment.bin>