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.