Ubuntu Security Notice 2935-2 - 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. 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. 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. 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. Various other issues were also addressed.
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Ubuntu Security Notice USN-2935-2
March 16, 2016
pam regression
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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
In general, a standard system update will make all the necessary changes.
References:
http://www.ubuntu.com/usn/usn-2935-2
http://www.ubuntu.com/usn/usn-2935-1
https://launchpad.net/bugs/1558114
Package Information:
https://launchpad.net/ubuntu/+source/pam/1.1.8-3.1ubuntu3.2
https://launchpad.net/ubuntu/+source/pam/1.1.8-1ubuntu2.2
https://launchpad.net/ubuntu/+source/pam/1.1.3-7ubuntu2.2