CVE-2016-1285: An error parsing input received by the rndc control channel can cause an assertion failure in sexpr.c or alist.c
  • 31 Oct 2018
  • 3 Minutes to read
  • Contributors
  • Dark
    Light
  • PDF

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

  • Dark
    Light
  • PDF

Article Summary

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)

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
2.0 Public Disclosure. 09 March 2016

Related Documents: See our BIND 9 Security Vulnerability Matrix 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 https://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, please encrypt your message using security-officer@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 https://www.isc.org/downloads/). 

ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy.

This Knowledgebase 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.