ISC dhclient did not strip or escape certain shell meta-characters in responses from the dhcp server (like hostname) before passing the responses on to dhclient-script. Depending on the script and OS, this can result in execution of exploit code on the client.
CVSS Score: 6.8 (AV:A/AC:L/Au:N/C:P/I:N/A:C)
For more information on CVSS scores, visit http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2
On SUSE systems, it is possible to disable hostname update by setting DHCLIENT_SET_HOSTNAME="no" in /etc/sysconfig/network/dhcp.
Other systems may add following line to dhclient-script at the beginning of the set_hostname() function:
In environments where filters/acls can be put into place to limit clients to accessing only legitimate dhcp servers, this will protect clients
from rogue dhcp servers deliberately trying to exploit this bug. However, this will not protect from compromised servers.
Upgrade to 3.1-ESV-R1, 4.1-ESV-R2 or 4.2.1-P1. https://www.isc.org/downloads/all
No patch is available for 4.0.x as it is EOL. Anyone running 4.1.x should upgrade to 4.1-ESV-R2.
Sebastian Krahmer and Marius Tomaschewski, SUSE Security Team
Mar29-Updated CVSS score
Do you have Questions? Questions regarding this advisory should go to firstname.lastname@example.org.
Do you need Software Support? Questions on ISC's Support services or other offerings should be sent to email@example.com. More information on ISC's support and other offerings are available at: http://www.isc.org/community/blog/201102/BIND-support
ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: https://www.isc.org/security-vulnerability-disclosure-policy
Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time.