Scientific Linux Security Update : dnsmasq on SL6.x i386/x86_64

This script is Copyright (C) 2013 Tenable Network Security, Inc.


Synopsis :

The remote Scientific Linux host is missing one or more security
updates.

Description :

It was discovered that dnsmasq, when used in combination with certain
libvirtd configurations, could incorrectly process network packets
from network interfaces that were intended to be prohibited. A remote,
unauthenticated attacker could exploit this flaw to cause a denial of
service via DNS amplification attacks. (CVE-2012-3411)

In order to fully address this issue, libvirt package users are
advised to install updated libvirt packages.

This update also fixes the following bug :

- Due to a regression, the lease change script was
disabled. Consequently, the 'dhcp-script' option in the
/etc/dnsmasq.conf configuration file did not work. This
update corrects the problem and the 'dhcp-script' option
now works as expected.

This update also adds the following enhancements :

- Prior to this update, dnsmasq did not validate that the
tftp directory given actually existed and was a
directory. Consequently, configuration errors were not
immediately reported on startup. This update improves
the code to validate the tftp root directory option. As
a result, fault finding is simplified especially when
dnsmasq is called by external processes such as libvirt.

- The dnsmasq init script used an incorrect Process
Identifier (PID) in the 'stop', 'restart', and
'condrestart' commands. Consequently, if there were some
dnsmasq instances running besides the system one started
by the init script, then repeated calling of 'service
dnsmasq' with 'stop' or 'restart' would kill all running
dnsmasq instances, including ones not started with the
init script. The dnsmasq init script code has been
corrected to obtain the correct PID when calling the
'stop', 'restart', and 'condrestart' commands. As a
result, if there are dnsmasq instances running in
addition to the system one started by the init script,
then by calling 'service dnsmasq' with 'stop' or
'restart' only the system one is stopped or restarted.

- When two or more dnsmasq processes were running with
DHCP enabled on one interface, DHCP RELEASE packets were
sometimes lost. Consequently, when two or more dnsmasq
processes were running with DHCP enabled on one
interface, releasing IP addresses sometimes failed. This
update sets the SO_BINDTODEVICE socket option on DHCP
sockets if running dnsmasq with DHCP enabled on one
interface. As a result, when two or more dnsmasq
processes are running with DHCP enabled on one
interface, they can release IP addresses as expected.

See also :

http://www.nessus.org/u?4bcbdc64

Solution :

Update the affected dnsmasq, dnsmasq-debuginfo and / or dnsmasq-utils
packages.

Risk factor :

Medium / CVSS Base Score : 5.0
(CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P)

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 64950 ()

Bugtraq ID:

CVE ID: CVE-2012-3411