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============================================================================
Ubuntu Security Notice USN-2935-3
March 17, 2016

pam regression
============================================================================

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

- Ubuntu 12.04 LTS

Summary:

USN-2935-1 introduced a regression in PAM.

Software Description:
- pam: Pluggable Authentication Modules

Details:

USN-2935-1 fixed vulnerabilities in PAM. The updates contained a packaging
change that prevented upgrades in certain multiarch environments. USN-2935-2
intended to fix the problem but was incomplete for Ubuntu 12.04 LTS. This
update fixes the problem in Ubuntu 12.04 LTS.

We apologize for the inconvenience.

Original advisory details:

 It was discovered that the PAM pam_userdb module incorrectly used a
 case-insensitive method when comparing hashed passwords. A local attacker
 could possibly use this issue to make brute force attacks easier. This
 issue only affected Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2013-7041)
 
 Sebastian Krahmer discovered that the PAM pam_timestamp module incorrectly
 performed filtering. A local attacker could use this issue to create
 arbitrary files, or possibly bypass authentication. This issue only
 affected Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2014-2583)
 
 Sebastien Macke discovered that the PAM pam_unix module incorrectly handled
 large passwords. A local attacker could possibly use this issue in certain
 environments to enumerate usernames or cause a denial of service.
 (CVE-2015-3238)

Update instructions:

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

Ubuntu 12.04 LTS:
  libpam-modules                  1.1.3-7ubuntu2.3

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

References:
  http://www.ubuntu.com/usn/usn-2935-3
  http://www.ubuntu.com/usn/usn-2935-1
  http://www.ubuntu.com/usn/usn-2935-2, https://launchpad.net/bugs/1558597

Package Information:
  https://launchpad.net/ubuntu/+source/pam/1.1.3-7ubuntu2.3