CVE-2016-1285: An error parsing input received by the rndc control channel can cause an assertion failure in sexpr.c or alist.c

Michael McNally mcnally at
Wed Mar 9 21:05:20 UTC 2016

CVE:                   CVE-2016-1285
Document Version:      2.0
Posting date:          09 March 2016
Program Impacted:      BIND
Versions affected:     9.2.0 -> 9.8.8, 9.9.0 -> 9.9.8-P3,
                       9.9.3-S1 -> 9.9.8-S5, 9.10.0 -> 9.10.3-P3
Severity:              High
Exploitable:           Remotely (on systems which accept control
                       channel input from remote addresses.)


   Testing by ISC has uncovered a defect in control channel input
   handling which can cause named to exit due to an assertion failure
   in sexpr.c or alist.c when a malformed packet is sent to named's
   control channel (the interface which allows named to be controlled
   using the 'rndc" server control utility).

   This assertion occurs before authentication but after
   network-address-based access controls have been applied.  Or in
   other words:  an attacker does not need to have a key or other
   authentication, but does need to be within the address list
   specified in the "controls" statement in named.conf which enables
   the control channel.  If no "controls" statement is present in
   named.conf, named still defaults to listening for control channel
   information on loopback addresses ( and ::1) if the
   file rndc.key is present in the configuration directory and
   contains a valid key.

   A search for similar problems revealed an associated defect in
   the rndc server control utility whereby a malformed response
   from the server could cause the rndc program to crash.  For
   completeness, it is being fixed at the same time even though
   this defect in the rndc utility is not in itself exploitable.


   All servers are vulnerable if they accept remote commands on the
   control channel.  Servers which are vulnerable can be stopped
   by an attacker sending the offending packet if the attacker is
   sending from a system listed within the address list specified
   in the "controls" statement (or from localhost if the control
   channel is using the default address list) resulting in denial
   of service to 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:


   Restrict access to the control channel (by using the "controls"
   configuration statement in named.conf) to allow connection only
   from trusted systems.

   Note that if no "controls" statement is present, named defaults
   to allowing control channel connections only from localhost
   ( and ::1) if and only if the file rndc.key exists in
   the configuration directory and contains valid key syntax.  If
   rndc.key is not present and no "controls" statement is present
   in named.conf, named will not accept commands on the control

Active exploits:

   No known active exploits.


   Upgrade to the patched release most closely related to your
   current version of BIND.

   + BIND 9 version 9.9.8-P4
   + BIND 9 version 9.10.3-P4

   BIND 9 Supported Preview edition is a feature preview version of
   BIND provided exclusively to eligible ISC Support customers.

   + BIND 9 Supported Preview Edition version 9.9.8-S6

Document Revision History:

   1.0 Advance Notification 09 March 2016
   1.1 "Versions affected" and "Solution" text expanded to cover BIND 9
        Supported Preview Edition, 03 March 2016
   2.0 Public Disclosure.  09 March 2016

Related Documents:

   See our BIND9 Security Vulnerability Matrix at 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

Do you still have questions?  Questions regarding this advisory
should go to security-officer at  To report a new issue,
please encrypt your message using security-officer at's PGP
key which can be found here:

If you are unable to use encrypted email, you may also report new
issues at:


   ISC patches only currently supported versions. When possible we
   indicate EOL versions affected.  (For current information on
   which versions are actively supported, please see

ISC Security Vulnerability Disclosure Policy: 

   Details of our current security advisory policy and practice can
   be found here:

This Knowledge Base article 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) 2001-2016 Internet Systems Consortium

More information about the bind-announce mailing list