USN-1140-2: PAM regression

Ubuntu Security Notice USN-1140-2

31st May, 2011

pam regression

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

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

Summary

The USN-1140-1 PAM update caused cron to stop working.

Software description

  • pam - Pluggable Authentication Modules

Details

USN-1140-1 fixed vulnerabilities in PAM. A regression was found that caused
cron to stop working with a "Module is unknown" error. As a result, systems
configured with automatic updates will not receive updates until cron is
restarted, these updates are installed or the system is rebooted. This
update fixes the problem.

We apologize for the inconvenience.

Original advisory details:

Marcus Granado discovered that PAM incorrectly handled configuration files
with non-ASCII usernames. A remote attacker could use this flaw to cause a
denial of service, or possibly obtain login access with a different users
username. This issue only affected Ubuntu 8.04 LTS. (CVE-2009-0887)

It was discovered that the PAM pam_xauth, pam_env and pam_mail modules
incorrectly handled dropping privileges when performing operations. A local
attacker could use this flaw to read certain arbitrary files, and access
other sensitive information. (CVE-2010-3316, CVE-2010-3430, CVE-2010-3431,
CVE-2010-3435)

It was discovered that the PAM pam_namespace module incorrectly cleaned the
environment during execution of the namespace.init script. A local attacker
could use this flaw to possibly gain privileges. (CVE-2010-3853)

It was discovered that the PAM pam_xauth module incorrectly handled certain
failures. A local attacker could use this flaw to delete certain unintended
files. (CVE-2010-4706)

It was discovered that the PAM pam_xauth module incorrectly verified
certain file properties. A local attacker could use this flaw to cause a
denial of service. (CVE-2010-4707)

Update instructions

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

Ubuntu 11.04:
libpam-modules 1.1.2-2ubuntu8.3
libpam0g 1.1.2-2ubuntu8.3
Ubuntu 10.10:
libpam-modules 1.1.1-4ubuntu2.3
libpam0g 1.1.1-4ubuntu2.3
Ubuntu 10.04 LTS:
libpam-modules 1.1.1-2ubuntu5.3
libpam0g 1.1.1-2ubuntu5.3
Ubuntu 8.04 LTS:
libpam-modules 0.99.7.1-5ubuntu6.4
libpam0g 0.99.7.1-5ubuntu6.4

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: 790538