This ISC Security Advisory applies only to releases of the BIND 9 Supported Preview Edition, which is a special feature-development branch of BIND that is made available solely to subscription support customers (who are also notified directly concerning any security issues identified in this series). Releases in the Supported Preview Edition branch are denoted by an "-S" suffix and a sequence number, e.g. "BIND 9.9.8-S1"
Features which are created for BIND 9 Supported Preview Edition are ported to main-line open-source BIND releases after they have been refined in the Supported Preview Edition.
Posting date: 3 February 2016
Program Impacted: BIND
9 Supported Preview Edition (sometimes called "BIND
9 Subscription Edition")
9.9.8-S1 -> 9.9.8-S4
An error in handling flag values in incoming queries can be exploited to
deliberately trigger a REQUIRE assertion failure in rdataset.c on servers using the "nxdomain-redirect" option in BIND 9 Supported Preview Edition.
Servers configured for NXDOMAIN redirection using the "nxdomain-redirect" option are at risk from a constructed query with the right combination of attributes. Successful exploitation of this bug allows an attacker to cause a nameserver running BIND 9 Supported Preview Edition to stop execution after encountering a REQUIRE assertion failure in rdataset.c, resulting in denial of service to clients.
Servers configured for NXDOMAIN redirection using a "type redirect" zone rather than the "nxdomain-redirect" option are not at risk.
The assertion failure logged is:
rdataset.c:147: REQUIRE(((rdataset) != ((void *)0)) && ((const isc__magic_t *)(rdataset)->magic == (('D') << 24 | ('N') << 16 | ('S') << 8 | ('R'))))
The underlying bug is an assignment of a flag value to the wrong variable; this bug has existed in all Supported Preview releases since 9.9.6-S1, but it was harmless prior to the introduction of the "nxdomain-redirect" option.
CVSS Score: 5.4
CVSS Vector: (AV:N/AC:H/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:H/Au:N/C:N/I:N/A:C)
Servers which do not use "nxdomain-redirect" are not at risk. Only servers using this feature of BIND 9 Supported Preview Edition are affected.
No known active exploits.
Solution: Choose one of the following two options:
- A patch which will apply to BIND 9 Supported Preview Edition version 9.9.8-S4 is available upon request.
- A correction for the defect is included in BIND 9 Supported Preview Edition version 9.9.8-S5.
Document Revision History:
1.0 Advance Notification 27 January, 2016
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 email@example.com. To report a new issue, please encrypt your message using firstname.lastname@example.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/.
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-01348 is the complete and official security advisory document.
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.
© 2001-2017 Internet Systems ConsortiumFor assistance with problems and questions for which you have not been able to find an answer in our Knowledge Base, we recommend searching our community mailing list archives and/or posting your question there (you will need to register there first for your posts to be accepted). The bind-users and the dhcp-users lists particularly have a long-standing and active membership.ISC relies on the financial support of the community to fund the development of its open source software products. If you would like to support future product evolution and maintenance as well having peace of mind knowing that our team of experts are poised to provide you with individual technical assistance whenever you call upon them, then please consider our Professional Subscription Support services - details can be found on our main website.