Synopsis

Low: sudo security and bug fix update

Type/Severity

Security Advisory: Low

Topic

An updated sudo package that fixes multiple security issues and several
bugs is now available for Red Hat Enterprise Linux 5.

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-2013-1776, CVE-2013-2776)

This update also fixes the following bugs:

• Due to a bug in the cycle detection algorithm of the visudo utility,

visudo incorrectly evaluated certain alias definitions in the /etc/sudoers
file as cycles. Consequently, a warning message about undefined aliases
appeared. This bug has been fixed, /etc/sudoers is now parsed correctly by
visudo and the warning message no longer appears. (BZ#849679)

• Previously, the 'sudo -l' command did not parse the /etc/sudoers file

correctly if it contained an Active Directory (AD) group. The file was
parsed only up to the first AD group information and then the parsing
failed with the following message:

sudo: unable to cache group ADDOM\admingroup, already exists

With this update, the underlying code has been modified and 'sudo -l' now
parses /etc/sudoers containing AD groups correctly. (BZ#855836)

• Previously, the sudo utility did not escape the backslash characters

contained in user names properly. Consequently, if a system used sudo
integrated with LDAP or Active Directory (AD) as the primary authentication
mechanism, users were not able to authenticate on that system. With this
update, sudo has been modified to process LDAP and AD names correctly and
the authentication process now works as expected. (BZ#869287)

• Prior to this update, the 'visudo -s (strict)' command incorrectly parsed

certain alias definitions. Consequently, an error message was issued. The
bug has been fixed, and parsing errors no longer occur when using 'visudo

• s'. (BZ#905624)

All sudo users are advised to upgrade to this updated package, which
contains backported patches to correct these issues.

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 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 Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 853203 - Sudo -i isn't passing command arguments containing spaces properly as of sudo-1.7.2p1-14.el5_8.3
• BZ - 856902 - Defauts:!<user> syntax in sudoers doesn't seem to work as expected
• BZ - 916363 - CVE-2013-1775 sudo: authentication bypass via reset system clock
• BZ - 916365 - CVE-2013-1776 sudo: bypass of tty_tickets constraints
• BZ - 949751 - CVE-2013-2776 sudo: bypass of tty_tickets constraints

CVEs

• CVE-2013-1776
• CVE-2013-1775
• CVE-2013-2776

References