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CVE-2016-9444: An unusually-formed DS record response could cause an assertion failure
Author: Michael McNally Reference Number: AA-01441 Views: 61436 Created: 2017-01-11 10:31 Last Updated: 2017-01-11 22:37 0 Rating/ Voters
Document Version: 
2.0
Posting date: 
11 Jan 2017
Program Impacted: 
BIND
Versions affected: 
9.6-ESV-R9 -> 9.6-ESV-R11-W1, 9.8.5 -> 9.8.8, 9.9.3 -> 9.9.9-P4, 9.9.9-S1 -> 9.9.9-S6, 9.10.0 -> 9.10.4-P4, 9.11.0 -> 9.11.0-P1
Severity: 
High
Exploitable: 
Remotely

Description:

An unusually-formed answer containing a DS resource record could trigger an assertion failure.  While the combination of properties which triggers the assertion should not occur in normal traffic, it is potentially possible for the assertion to be triggered deliberately by an attacker sending a specially-constructed answer having the required properties.

Impact:

This vulnerability occurs during the processing of an answer packet received in response to a query.  As a result, recursive servers are at the greatest risk; authoritative servers are at risk only to the extent that they perform a limited set of queries (for example, in order to do zone service - see https://kb.isc.org/article/AA-00914/55/Why-does-my-authoritative-only-nameserver-try-to-query-the-root-nameservers.html)

Successful exploitation of this vulnerability will cause named to encounter an assertion failure and stop executing, resulting in denial of service to clients.

CVSS Score:  7.5

CVSS Vector:  CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Workarounds:

None known.

Active exploits:

No known active exploits.

Solution:  Upgrade to the patched release most closely related to your current version of BIND. These can all be downloaded from http://www.isc.org/downloads.

  • BIND 9 version 9.9.9-P5
  • BIND 9 version 9.10.4-P5
  • BIND 9 version 9.11.0-P2

BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.

  • BIND 9 version 9.9.9-S7

Document Revision History:

1.0 Advance Notification, 03 January 2017
2.0 Public Announcement, 11 January 2017

Related Documents:

See our BIND9 Security Vulnerability Matrix at https://kb.isc.org/article/AA-00913 for a complete listing of Security Vulnerabilities and versions affected.

If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit http://www.isc.org/support/.

Do you still have questions?  Questions regarding this advisory should go to security-officer@isc.orgTo report a new issue, please encrypt your message using security-officer@isc.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/.  If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/.

Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected.  (For current information on which versions are actively supported, please see http://www.isc.org/downloads/). 

ISC Security Vulnerability Disclosure Policy:  Details of our current security advisory policy and practice can be found here: https://kb.isc.org/article/AA-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html

This Knowledge Base article https://kb.isc.org/article/AA-01441 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.


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