CVE:                   CVE-2016-1285
Document Version:      1.1
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.)

Description:

   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 (127.0.0.1 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.

Impact:

   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:
   http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:L/Au:N/C:N/I:N/A:C)

Workarounds:

   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
   (127.0.0.1 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
   channel.

Active exploits:

   No known active exploits.

Solution:

   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 version 9.9.8-S6

Document Revision History:

   1.0 Advance Notification 02 March 2016

   1.1 "Versions affected" and "Solution" text expanded to cover
   BIND 9 Supported Preview Edition, 03 March 2016

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.org.  To report a new issue,
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   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-01352 is
the complete and official security advisory document.

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