An unintentional defect in the handling of NSEC3-signed zones can cause BIND to be crashed by a specific set of queries.
Posting date: 13 Jan 2014
9.6.0.x -> 9.6-ESV-R10-P1, 9.7 (all versions), 9.8.0 -> 9.8.6-P1, 9.9.0 -> 9.9.4-P1. Development releases 9.6-ESV-R11b1, 9.8.7b1, and 9.9.5b1 are also affected.
Because of a defect in handling queries for NSEC3-signed zones, BIND can crash with an "INSIST" failure in name.c when processing queries possessing certain properties. By exploiting this defect an attacker deliberately constructing a query with the right properties could achieve denial of service against an authoritative nameserver serving NSEC3-signed zones.
Please Note: Versions of BIND 9.7 are also affected, but this branch is beyond its "end of life" (EOL) and no longer receives testing or security fixes from ISC. For current information on which versions are actively supported, please see http://www.isc.org/downloads/software-support-policy/bind-software-status/.
Authoritative nameservers serving at least one NSEC3-signed zone are vulnerable to this defect. Recursive-only servers are not at risk. Authoritative servers which do not serve NSEC3-signed zones are not at risk.
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: http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:H/Au:N/C:N/I:N/A:C)
There are no known active exploits but limited discussion of this issue has taken place on a public mailing list.
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 9.6-ESV-R10-P2
- BIND 9 version 9.8.6-P2
- BIND 9 version 9.9.4-P2
Acknowledgements: ISC would like to thank Jared Mauch for reporting this issue.
Document Revision History:
1.0 Phase One, Advance Notification 06 January, 2014
1.1 Phase One+, Advance Notification 08 January, 2014
1.2 Phase Two & Three, Advance Notification 10 January, 2014
1.3 Changed CVSS Equation to Vector and edited Exploits 11 January, 2014
2.0 Phase Four, Public Release 13 January, 2014
See our BIND Security Matrix for a complete listing of Security Vulnerabilities and versions affected.
This Knowledge Base article https://kb.isc.org/article/AA-01085 provides additional information and Frequently Asked Questions about this advisory.
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Note: ISC patches only currently supported versions. When possible we indicate EOL versions affected.
ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found here: ISC Software Defect and Security Vulnerability Disclosure Policy
This Knowledge Base article https://kb.isc.org/article/AA-01078/74/ is the complete and official security advisory document.
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