USN-1237-1: PAM vulnerabilities

24 October 2011

pam vulnerabilities

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

  • Ubuntu 11.10
  • Ubuntu 11.04
  • Ubuntu 10.10
  • Ubuntu 10.04 LTS
  • Ubuntu 8.04 LTS

Summary

PAM could be made to crash or run programs as an administrator.

Software Description

  • pam - Pluggable Authentication Modules

Details

Kees Cook discovered that the PAM pam_env module incorrectly handled certain malformed environment files. A local attacker could use this flaw to cause a denial of service, or possibly gain privileges. The default compiler options for affected releases should reduce the vulnerability to a denial of service. (CVE-2011-3148)

Kees Cook discovered that the PAM pam_env module incorrectly handled variable expansion. A local attacker could use this flaw to cause a denial of service. (CVE-2011-3149)

Stephane Chazelas discovered that the PAM pam_motd module incorrectly cleaned the environment during execution of the motd scripts. In certain environments, a local attacker could use this to execute arbitrary code as root, and gain privileges.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 11.10
libpam-modules - 1.1.3-2ubuntu2.1
Ubuntu 11.04
libpam-modules - 1.1.2-2ubuntu8.4
Ubuntu 10.10
libpam-modules - 1.1.1-4ubuntu2.4
Ubuntu 10.04 LTS
libpam-modules - 1.1.1-2ubuntu5.4
Ubuntu 8.04 LTS
libpam-modules - 0.99.7.1-5ubuntu6.5

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