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Ubuntu Security Notice USN-1140-1
May 30, 2011

pam vulnerabilities
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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:

An attacker could cause PAM to read or delete arbitrary files or cause it
to crash.

Software Description:
- pam: Pluggable Authentication Modules

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 versions:

Ubuntu 11.04:
  libpam-modules                  1.1.2-2ubuntu8.2

Ubuntu 10.10:
  libpam-modules                  1.1.1-4ubuntu2.2

Ubuntu 10.04 LTS:
  libpam-modules                  1.1.1-2ubuntu5.2

Ubuntu 8.04 LTS:
  libpam-modules                  0.99.7.1-5ubuntu6.3

In general, a standard system update will make all the necessary changes.

References:
  CVE-2009-0887, CVE-2010-3316, CVE-2010-3430, CVE-2010-3431,
  CVE-2010-3435, CVE-2010-3853, CVE-2010-4706, CVE-2010-4707

Package Information:
  https://launchpad.net/ubuntu/+source/pam/1.1.2-2ubuntu8.2
  https://launchpad.net/ubuntu/+source/pam/1.1.1-4ubuntu2.2
  https://launchpad.net/ubuntu/+source/pam/1.1.1-2ubuntu5.2
  https://launchpad.net/ubuntu/+source/pam/0.99.7.1-5ubuntu6.3