RHSA-2012:0309 - Security Advisory

Topic

An updated sudo package that fixes one security issue and various 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. 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 sudo (superuser do) utility allows system administrators to give
certain users the ability to run commands as root.

A flaw was found in the sudo password checking logic. In configurations
where the sudoers settings allowed a user to run a command using sudo
with only the group ID changed, sudo failed to prompt for the user's
password before running the specified command with the elevated group
privileges. (CVE-2011-0010)

In addition, this update fixes the following bugs:

• A NULL pointer dereference bug caused the sudo utility to terminate

unexpectedly with a segmentation fault. This happened if the utility was
run with the -g option and configured not to demand the password from the
user who ran the sudo utility. With this update, the code has been modified
and the problem no longer occurs. (BZ#673072)

• The sudo utility failed to load sudoers from an LDAP (Lightweight

Directory Access Protocol) server after the sudo tool was upgraded. This
happened because the upgraded nsswitch.conf file did not contain the
instruction to search for sudoers on the LDAP server. This update adds the
lost instruction to /etc/nsswitch.conf and the system searches for sources
of sudoers on the local file system and then on LDAP, if applicable.
(BZ#617061)

• The sudo tool interpreted a Runas alias specifying a group incorrectly as

a user alias and the alias seemed to be ignored. With this update, the code
for interpreting such aliases has been modified and the Runas group aliases
are honored as expected. (BZ#627543)

• Prior to this update, sudo did not parse comment characters (#) in the

ldap.conf file correctly and could fail to work. With this update, parsing
of the LDAP configuration file has been modified and the comment characters
are parsed correctly. (BZ#750318)

• The sudo utility formats its output to fit the width of the terminal

window. However, this behavior is undesirable if the output is redirected
through a pipeline. With this update, the output formatting is not applied
in the scenario described. (BZ#697111)

• Previously, the sudo utility performed Security-Enhanced Linux (SELinux)

related initialization after switching to an unprivileged user. This
prevented the correct setup of the SELinux environment before executing the
specified command and could potentially cause an access denial. The bug has
been fixed by backporting the SELinux related code and the execution model
from a newer version of sudo. (BZ#477185)

• On execv(3) function failure, the sudo tool executed an auditing call

before reporting the failure. The call reset the error state and,
consequently, the tool incorrectly reported that the command succeeded.
With this update, the code has been modified and the problem no longer
occurs. (BZ#673157)

All users of sudo are advised to upgrade to this updated package, which
resolves 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/kb/docs/DOC-11259

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 - 477185 - sudo changes uid before calling SELInux calls, preventing it from setting terminal context when using non priv account
• BZ - 627543 - The Runas_Spec are ignored in sudoers file
• BZ - 668879 - CVE-2011-0010 sudo: does not ask for password on GID changes
• BZ - 673072 - sudo segfault
• BZ - 673157 - sudo fails to report error correctly when execv(3) fails
• BZ - 697111 - sudo -l inserts new lines based on terminal width, causing errors when output is piped.

CVEs

• CVE-2011-0010

References

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