CVE-2016-9444: An unusually-formed DS record response could cause an assertion failure

[Michael McNally]

CVE:                    CVE-2016-9444
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/)

   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.

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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

This Knowledge Base article https://kb.isc.org/article/AA-01441 is
the complete and official security advisory document.

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