Knowledge Base ISC Main Website Ask a Question/Contact ISC
CVE-2010-3616: DHCP: Server Hangs with TCP to Failover Peer Port
Author: Cathy Almond Reference Number: AA-00966 Views: 8366 Created: 2013-05-29 14:39 Last Updated: 2013-05-30 17:17 0 Rating/ Voters

If a server receives a TCP connection on a port that has been configured for communication with a failover peer, this can cause it to become non-responsive to all normal DHCP protocol traffic.

Posting date:
10 Dec 2010
Program Impacted: 
ISC DHCP
Versions affected: 
4.2
Severity:
High
Exploitable: 
Remotely

Description:

If a TCP connection is established to the server on a port which has been configured for communication with a failover peer, this can cause it to become non-responsive to all normal DHCP protocol traffic. The server will progress to a communications-interrupted state - but in addition will also cease to provide DHCP services to clients. The server must be restarted to resume normal operation.

Impact and Risk Assessment:

This can be used as an attack vector against servers that are configured for failover partnerships

CVSS Score:  7.8

CVSS Equation:  (AV:N/AC:L/Au:N/C:N/I:N/A:C)

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:L/Au:N/C:N/I:N/A:C)  

Workarounds:

Users running DHCP servers in failover configurations may be able to minimise the risk to TCP ports used for peer-peer DHCP server communication by careful packet filtering on the hosts and network gateways that limits access to traffic between the configured failover peers - but ideally they should upgrade. (Regardless of which version of DHCP is deployed, users are advised that it is good security practice to limit traffic to their omapi and failover ports via packet filters, firewalls etc.)

Active exploits:

None known at this time. Issue found by a user and reported via the dhcp-users community mailing list, therefore consider this vulnerability public.

Solution: 

Upgrade DHCP to 4.2.0-P2.

Acknowledgements: Brad Bendily for finding and testing the problem.

Related Documents:

If you'd like more information on our Forum or product support please visit www.isc.org/support.

Do you still have questions?  Questions regarding this advisory should go to security-officer@isc.org

Note: ISC patches only currently supported versions.

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

This Knowledge Base article https://kb.isc.org/article/AA-00966 is the complete and official security advisory document.

Legal Disclaimer:
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.  A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors.


© 2001-2017 Internet Systems Consortium

For assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership.

ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website.

Feedback
  • There is no feedback for this article
Quick Jump Menu