Low: sudo security, bug fix and enhancement update

Synopsis

Low: sudo security, bug fix and enhancement update

Type/Severity

Security Advisory: Low

Topic

An updated sudo package that fixes two security issues, several bugs, and
adds two enhancements is now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having low
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

The sudo (superuser do) utility allows system administrators to give
certain users the ability to run commands as root.

A flaw was found in the way sudo handled time stamp files. An attacker able
to run code as a local user and with the ability to control the system
clock could possibly gain additional privileges by running commands that
the victim user was allowed to run via sudo, without knowing the victim's
password. (CVE-2013-1775)

It was found that sudo did not properly validate the controlling terminal
device when the tty_tickets option was enabled in the /etc/sudoers file.
An attacker able to run code as a local user could possibly gain additional
privileges by running commands that the victim user was allowed to run via
sudo, without knowing the victim's password. (CVE-2013-2776, CVE-2013-2777)

This update also fixes the following bugs:

• Previously, sudo did not support netgroup filtering for sources from the
  System Security Services Daemon (SSSD). Consequently, SSSD rules were
  applied to all users even when they did not belong to the specified
  netgroup. With this update, netgroup filtering for SSSD sources has been
  implemented. As a result, rules with a netgroup specification are applied
  only to users that are part of the netgroup. (BZ#880150)
  
• When the sudo utility set up the environment in which it ran a command,
  it reset the value of the RLIMIT_NPROC resource limit to the parent's value
  of this limit if both the soft (current) and hard (maximum) values of
  RLIMIT_NPROC were not limited. An upstream patch has been provided to
  address this bug and RLIMIT_NPROC can now be set to "unlimited".
  (BZ#947276)
  
• Due to the refactoring of the sudo code by upstream, the SUDO_USER
  variable that stores the name of the user running the sudo command was not
  logged to the /var/log/secure file as before. Consequently, user name
  "root" was always recorded instead of the real user name. With this update,
  the previous behavior of sudo has been restored. As a result, the expected
  user name is now written to /var/log/secure. (BZ#973228)
  
• Due to an error in a loop condition in sudo's rule listing code, a buffer
  overflow could have occurred in certain cases. This condition has been
  fixed and the buffer overflow no longer occurs. (BZ#994626)
  

In addition, this update adds the following enhancements:

• With this update, sudo has been modified to send debug messages about
  netgroup matching to the debug log. These messages should provide better
  understanding of how sudo matches netgroup database records with values
  from the running system and what the values are exactly. (BZ#848111)
  
• With this update, sudo has been modified to accept the ipa_hostname value
  from the /etc/sssd/sssd.conf configuration file when matching netgroups.
  (BZ#853542)
  

All sudo users are advised to upgrade to this updated package, which
contains 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/site/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 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

Fixes

• BZ - 856901 - Defauts:!<user> syntax in sudoers doesn't seem to work as expected
• BZ - 880150 - sssd +netgroup sudoUser is always matched
• BZ - 886648 - Access granted with invalid sudoRunAsUser/sudoRunAsGroup
• BZ - 916363 - CVE-2013-1775 sudo: authentication bypass via reset system clock
• BZ - 949751 - CVE-2013-2776 sudo: bypass of tty_tickets constraints
• BZ - 949753 - CVE-2013-2777 sudo: bypass of tty_tickets constraints
• BZ - 994563 - Warning in visudo: cycle in Host_Alias even without cycle
• BZ - 994626 - sudo -u <user> sudo -l show error: *** glibc detected *** sudo: realloc(): invalid next size: 0x00007f4ae2d10ec0 ***

CVEs

• CVE-2013-1775
• CVE-2013-2776
• CVE-2013-2777

References

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