Red Hat Bugzilla – Bug 883719
CVE-2012-5627 mysql: efficient password guessing attack using change_user()
Last modified: 2015-08-22 12:02:01 EDT
A vulnerability was found in the handling of password salt values in MySQL. When a user logs into MySQL a salt value is generated that is then used to prevent password guessing attacks (since the salt value must be known in order to send a password). This salt value is created at the start of a session and used for the entire session, once authenticated an attacker can use the MySQL "change_user" command to attempt to login as a different, as the salt value is known a password guessing attack will be much more efficient.
I'm not really convinced that this is a problem at all, or that selecting a new salt would make much difference. Per the reference link, the main time savings is from not having to establish a new connection. You still need a precalculated table of common password hashes, if you hope to avoid doing the hashing on-the-fly.
MariaDB upstream bug:
The CVE identifier of CVE-2012-5627 has been assigned to this issue:
(In reply to comment #1)
> I'm not really convinced that this is a problem at all, or that selecting a
> new salt would make much difference. Per the reference link, the main time
> savings is from not having to establish a new connection. You still need a
> precalculated table of common password hashes, if you hope to avoid doing
> the hashing on-the-fly.
Agree, changing bug summary.
This issue has not been addressed by the recent January 2013 CPU containing mysql security fixes.
Deferring this flaw till upstream fixes it.
This issue affects the version of mysql as shipped with Fedora-17 and Fedora-18.
Red Hat Product Security has rated this issue as having Low security impact. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.