4.6 - RHSA-2013:0521

Problem Description:

Updated pam packages that fix two security issues, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Desktop (v. 6) - i386, x86_64 Red Hat Enterprise Linux Desktop Optional (v. 6) - i386, x86_64 Red Hat Enterprise Linux HPC Node (v. 6) - x86_64 Red Hat Enterprise Linux HPC Node Optional (v. 6) - x86_64 Red Hat Enterprise Linux Server (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Workstation (v. 6) - i386, x86_64

3. Description:

Pluggable Authentication Modules (PAM) provide a system whereby administrators can set up authentication policies without having to recompile programs to handle authentication.

A stack-based buffer overflow flaw was found in the way the pam_env module parsed users' "~/.pam_environment" files. If an application's PAM configuration contained "user_readenv=1" (this is not the default), a local attacker could use this flaw to crash the application or, possibly, escalate their privileges. (CVE-2011-3148)

A denial of service flaw was found in the way the pam_env module expanded certain environment variables. If an application's PAM configuration contained "user_readenv=1" (this is not the default), a local attacker could use this flaw to cause the application to enter an infinite loop. (CVE-2011-3149)

Red Hat would like to thank Kees Cook of the Google ChromeOS Team for reporting the CVE-2011-3148 and CVE-2011-3149 issues.

These updated pam packages include numerous bug fixes and enhancements. Space precludes documenting all of these changes in this advisory. Users are directed to the Red Hat Enterprise Linux 6.4 Technical Notes, linked to in the References, for information on the most significant of these changes.

All pam users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements.

4. Solution:

Before applying this update, make sure all previously-released errata relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258

5. Bugs fixed (http://bugzilla.redhat.com/):

588893 - pam does not enforce password complexity restrictions on root 673398 - request for additional pam_cracklib checks 723297 - limits.conf should mention limits.d directory 746619 - CVE-2011-3148 pam (pam_env): Stack-based buffer overflow by parsing user's pam_environment file 746620 - CVE-2011-3149 pam (pam_env): Infinite loop by expanding certain arguments 750601 - pam_namespace cannot verify status of SELinux in MLS 811168 - fix pam_get_authtok_verify() to respect the authtok_type= option 811243 - pam_cracklib: difignore is no-op in the current package - needs man page update 815516 - pam remember can check wrong username if it is a substring of another username