RHSA-2013:1213 - Security Advisory

Topic

Updated gdm and initscripts packages that fix one security issue are now
available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having
important security impact. A Common Vulnerability Scoring System (CVSS)
base score, which gives a detailed severity rating, is available from the
CVE link in the References section.

Description

The GNOME Display Manager (GDM) provides the graphical login screen, shown
shortly after boot up, log out, and when user-switching.

A race condition was found in the way GDM handled the X server sockets
directory located in the system temporary directory. An unprivileged user
could use this flaw to perform a symbolic link attack, giving them write
access to any file, allowing them to escalate their privileges to root.
(CVE-2013-4169)

Note that this erratum includes an updated initscripts package. To fix
CVE-2013-4169, the vulnerable code was removed from GDM and the initscripts
package was modified to create the affected directory safely during the
system boot process. Therefore, this update will appear on all systems,
however systems without GDM installed are not affected by this flaw.

Red Hat would like to thank the researcher with the nickname vladz for
reporting this issue.

All users should upgrade to these updated packages, which correct this
issue. The system must be rebooted for this update to take effect.

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/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.9 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.9 ia64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.9 i386
• Red Hat Enterprise Linux Server from RHUI 5 i386
• Red Hat Enterprise Linux Server - AUS 5.9 x86_64
• Red Hat Enterprise Linux Server - AUS 5.9 ia64
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 5.9 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 5.9 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server - AUS 5.9 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 5.9 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 5.9 i386

Fixes

• BZ - 988498 - CVE-2013-4169 gdm: TOCTTOU race condition on /tmp/.X11-unix

CVEs

• CVE-2013-4169

References

• https://access.redhat.com/security/updates/classification/#important