RHSA-2013:0521 - Security Advisory

Topic

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.

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.

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

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

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

CVEs

• CVE-2011-3149
• CVE-2011-3148

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/6.4_Technical_Notes/pam.html