CVE-2016-2776: Assertion Failure in buffer.c While Building Responses to a Specifically Constructed Request
Document version: 2.1
Posting date: 2016-09-27
Program impacted: BIND
Versions affected: 9.0.x -> 9.8.x, 9.9.0->9.9.9-P2, 9.9.3-S1->9.9.9-S3, 9.10.0->9.10.4-P2, 9.11.0a1->9.11.0rc1
Testing by ISC has uncovered a critical error condition which can occur when a nameserver is constructing a response. A defect in the rendering of messages into packets can cause named to exit with an assertion failure in
buffer.c while constructing a response to a query that meets certain criteria.
This assertion can be triggered even if the apparent source address isn't allowed to make queries (i.e. doesn't match
Impact: All servers are vulnerable if they can receive request packets from any source.
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: No practical workarounds exist.
A step-by-step breakdown of the issue has been published and working Metasploit code is available. Crashes have been reported that appear to be the result of active exploitation.
Solution: Upgrade to the patched release most closely related to your current version of BIND. These can all be downloaded from https://www.isc.org/downloads.
- BIND 9 version 9.9.9-P3
- BIND 9 version 9.10.4-P3
- BIND 9 version 9.11.0rc3
BIND 9 Supported Preview edition is a feature preview version of BIND provided exclusively to eligible ISC Support customers.
- BIND 9 version 9.9.9-S5
Document Revision History:
1.0 Advance Notification, 14 September 2016
1.1 Added information about the Stable Preview release to versions affected; updated solution section to reflect replacing 9.11.0rc2 with 9.11.0rc3 and 9.9.9-S4 with 9.9.9-S5, 21 September 2016
2.0 Posting date changed and public disclosure, 27 September 2016
2.1 Updated 'Active exploits' section, 4 October 2016
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 firstname.lastname@example.org. To report a new issue, please encrypt your message using email@example.com'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 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.
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