USN-2935-2: PAM regression

16 March 2016

pam regression

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

  • Ubuntu 15.10
  • Ubuntu 14.04 LTS
  • 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. This update fixes the problem.

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 15.10
libpam-modules - 1.1.8-3.1ubuntu3.2
Ubuntu 14.04 LTS
libpam-modules - 1.1.8-1ubuntu2.2
Ubuntu 12.04 LTS
libpam-modules - 1.1.3-7ubuntu2.2

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.

References