RHSA-2012:0810 - Security Advisory

Topic

Updated busybox packages that fix two security issues and several bugs are
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

BusyBox provides a single binary that includes versions of a large number
of system commands, including a shell. This can be very useful for
recovering from certain types of system failures, particularly those
involving broken shared libraries.

A buffer underflow flaw was found in the way the uncompress utility of
BusyBox expanded certain archive files compressed using Lempel-Ziv
compression. If a user were tricked into expanding a specially-crafted
archive file with uncompress, it could cause BusyBox to crash or,
potentially, execute arbitrary code with the privileges of the user
running BusyBox. (CVE-2006-1168)

The BusyBox DHCP client, udhcpc, did not sufficiently sanitize certain
options provided in DHCP server replies, such as the client hostname. A
malicious DHCP server could send such an option with a specially-crafted
value to a DHCP client. If this option's value was saved on the client
system, and then later insecurely evaluated by a process that assumes the
option is trusted, it could lead to arbitrary code execution with the
privileges of that process. Note: udhcpc is not used on Red Hat Enterprise
Linux by default, and no DHCP client script is provided with the busybox
packages. (CVE-2011-2716)

This update also fixes the following bugs:

• Prior to this update, the "findfs" command did not recognize Btrfs

partitions. As a consequence, an error message could occur when dumping a
core file. This update adds support for recognizing such partitions so
the problem no longer occurs. (BZ#751927)

• If the "grep" command was used with the "-F" and "-i" options at the

same time, the "-i" option was ignored. As a consequence, the "grep -iF"
command incorrectly performed a case-sensitive search instead of an
insensitive search. A patch has been applied to ensure that the combination
of the "-F" and "-i" options works as expected. (BZ#752134)

• Prior to this update, the msh shell did not support the "set -o pipefail"

command. This update adds support for this command. (BZ#782018)

• Previously, the msh shell could terminate unexpectedly with a

segmentation fault when attempting to execute an empty command as a result
of variable substitution (for example msh -c '$nonexistent_variable').
With this update, msh has been modified to correctly interpret such
commands and no longer crashes in this scenario. (BZ#809092)

• Previously, the msh shell incorrectly executed empty loops. As a

consequence, msh never exited such a loop even if the loop condition was
false, which could cause scripts using the loop to become unresponsive.
With this update, msh has been modified to execute and exit empty loops
correctly, so that hangs no longer occur. (BZ#752132)

All users of busybox are advised to upgrade to these updated packages,
which contain backported patches to fix 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/knowledge/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 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 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 Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 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 - 201919 - CVE-2006-1168 ncompress: .bss buffer underflow in decompression
• BZ - 725364 - CVE-2011-2716 busybox: udhcpc insufficient checking of DHCP options
• BZ - 752134 - "busybox grep -Fi" doesn't work as expected
• BZ - 809092 - msh crasher bug

CVEs

• CVE-2006-1168
• CVE-2011-2716

References

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