CVE-2017-3135: Combination of DNS64 and RPZ Can Lead to Crash

[Brian Conry]

Some configurations using both DNS64 and RPZ can lead to an INSIST
assertion failure or a NULL pointer read; in either case named will
terminate.

CVE:               CVE-2017-3135
Document Version:  2.0
Posting date:      08 Feb 2017
Program Impacted:  BIND
Versions affected: 9.9.3-S1 -> 9.9.9-S7, 9.9.3 -> 9.9.9-P5, 9.9.10b1,
                   9.10.0 -> 9.10.4-P5, 9.10.5b1, 9.11.0 -> 9.11.0-P2,
                   9.11.1b1
Severity:          High, for servers with specific configurations
Exploitable:       Remotely, but only affecting servers with specific
                   configurations

Description:

    Under some conditions when using both DNS64 and RPZ to rewrite query
    responses, query processing can resume in an inconsistent state
    leading to either an INSIST assertion failure or an attempt to read
    through a NULL pointer.

Impact:

    Servers utilizing both DNS64 and RPZ are potentially susceptible to
    encountering this condition.  When this condition occurs, it will
    result in either an INSIST assertion failure (and subsequent abort)
    or an attempt to read through a NULL pointer.  On most platforms a
    NULL pointer read leads to a segmentation fault (SEGFAULT), which
    causes the process to be terminated.

    Only servers which are configured to simultaneously use both
    Response Policy Zones (RPZ) and DNS64 (a method for synthesizing
    AAAA records from A records) can be affected by this vulnerability.

CVSS Score:  7.5
CVSS 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:

    While it is possible to avoid the condition by removing either DNS64
    or RPZ from the configuration, or by carefully restricting the
    contents of the policy zone, for an affected configuration the most
    practical and safest course of action is to upgrade to a version of
    BIND without this vulnerability.

Active exploits:

    No known active exploits.

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 9.9.9-P6
        BIND 9 version 9.10.4-P6
        BIND 9 version 9.11.0-P3

    BIND Supported Preview Edition is a special feature preview branch
    of BIND provided to eligible ISC support customers.

        BIND 9 version 9.9.9-S8

Acknowledgements:

    ISC would like to thank Ramesh Damodaran(Infoblox) and Aliaksandr
    Shubnik (Infoblox) for reporting the issue and assisting us in the
    investigation.

Document Revision History:

    1.0 Advance Notification 01 Feb, 2017
    2.0 Public Announcement 08 Feb, 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.

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

This Knowledge Base article https://kb.isc.org/article/AA-01453 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) 2001-2017 Internet Systems Consortium