CVE-2015-5722: Parsing malformed keys may cause BIND to exit due to a failed assertion in buffer.c

[Michael McNally]

CVE:                       CVE-2015-5722
Document Version:          2.0
Posting date:              2 September 2015
Program Impacted:          BIND
Versions affected:         BIND 9.0.0 -> 9.8.8,  BIND 9.9.0 -> 9.9.7-P2, and
                           BIND 9.10.0 -> 9.10.2-P3
Severity:                  Critical
Exploitable:               Remotely

Description:

   Parsing a malformed DNSSEC key can cause a validating resolver
   to exit due to a failed assertion in buffer.c.  It is possible
   for a remote attacker to deliberately trigger this condition,
   for example by using a query which requires a response from a
   zone containing a deliberately malformed key.

Impact:

   Recursive servers are at greatest risk but an authoritative
   server could be affected if an attacker controls a zone the
   server must query against to perform its zone service.

   Servers which are affected may terminate with an assertion
   failure, causing denial of service to all clients.

CVSS Score:                7.8
CVSS Vector:               (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:
   https://nvd.nist.gov/cvss.cfm?calculator&version=2&vector=(AV:N/AC:L/Au:N/C:N/I:N/A:C)

Workarounds:

   Servers which are not performing validation are not at risk from
   this defect (but are at increased risk from other types of DNS
   attack.)  ISC does not recommend disabling validation to deal with
   this issue; upgrading to a fixed version is the preferred solution.

Active exploits:

   None known

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 9.9.7-P3
   +  BIND 9 version 9.10.2-P4

   BIND development releases scheduled to be published at the same
   time as the public disclosure of this vulnerability will also
   contain the fix for this security issue.

   +  BIND 9 version 9.9.8rc1
   +  BIND 9 version 9.10.3rc1

Acknowledgements:

   ISC would like to thank Hanno Boeck from the Fuzzing Project for
   discovering and reporting this defect.  We would also like to
   express our appreciation to the developers of the American Fuzzy
   Lop tool, which has been instrumental in revealing recently-disclosed
   vulnerabilities in BIND.

Document Revision History:

   1.0 Advance Notification 19 August 2015
   1.1 "Versions affected" information clarified  24 August, 2015
   2.0 Public Disclosure  2 September, 2015

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 at isc.org.  To report a new issue,
please encrypt your message using security-officer at 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-01287 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.

(c) 2001-2015 Internet Systems Consortium