CVE-2016-9778: An error handling certain queries using the nxdomain-redirect feature could cause a REQUIRE assertion failure in db.c

Michael McNally mcnally at isc.org
Wed Jan 11 22:35:40 UTC 2017


CVE:                    CVE-2016-9778
Document Version:       2.0
Posting date:           11 Jan 2017
Program Impacted:       BIND
Versions affected:      9.9.8-S1 -> 9.9.8-S3, 9.9.9-S1 -> 9.9.9-S6,
9.11.0-9.11.0 -> P1
Severity:               High (for affected configurations)
Exploitable:            Remotely

Description:

   An error in handling certain queries can cause an assertion
   failure when a server is using the nxdomain-redirect feature to
   cover a zone for which it is also providing authoritative service.
   A vulnerable server could be intentionally stopped by an attacker
   if it was using a configuration that met the criteria for the
   vulnerability and if the attacker could cause it to accept a
   query that possessed the required attributes.

   Please note: This vulnerability affects the "nxdomain-redirect"
   feature, which is one of two methods of handling NXDOMAIN
   redirection, and is only available in certain versions of BIND.
   Redirection using zones of type "redirect" is not affected by
   this vulnerability.

Impact:

   Only servers which are performing NXDOMAIN redirection using the
   "nxdomain-redirect" function are potentially vulnerable and then
   only a subset of those servers.  In order to be affected a server
   must be using nxdomain-redirect AND must be redirecting NXDOMAIN
   responses for a zone for which the server also provides authoritative
   service -- therefore a purely recursive server is not at risk,
   either.  Successful exploitation of the vulnerability will cause
   named to stop execution after encountering a REQUIRE assertion
   failure in db.c, resulting in denial of service to clients.

CVSS Score:             7.5
CVSSv3 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:

   Either provide an ordinary (that is: not redirected) NXDOMAIN
   for non-existent resource records in zones for which authoritative
   data is served on the same server or use redirect zones instead
   of the nxdomain-redirect feature.

Active exploits:

   No known active exploits.

Solution:

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

     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 9.9.9-S7

Document Revision History:

   1.0 Advance Notification, 03 January 2017
   1.1 Updated Versions affected to include 9.11.0-P1, 04 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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Advance Security Notifications, please visit http://www.isc.org/support/.

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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-01442 is
the complete and official security advisory document.

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