USN-2935-3: PAM regression
17 March 2016
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 12.04 LTS
USN-2935-1 introduced a regression in PAM.
- pam - Pluggable Authentication Modules
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)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.