USN-2935-2: PAM regression

Ubuntu Security Notice USN-2935-2

16th 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 version:

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

LP: 1558114