USN-2935-3: PAM regression

Ubuntu Security Notice USN-2935-3

17th March, 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)