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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.1778 CVE-2015-4620: Specially Constructed Zone Data Can Cause a Resolver to Crash when Validating 8 July 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIND Publisher: ISC Operating System: Windows UNIX variants (UNIX, Linux, OSX) Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2015-4620 Original Bulletin: https://kb.isc.org/article/AA-01267/0 Comment: This advisory references vulnerabilities in products which run on platforms other than Windows. It is recommended that administrators running BIND check for an updated version of the software for their operating system. - --------------------------BEGIN INCLUDED TEXT-------------------- CVE-2015-4620: Specially Constructed Zone Data Can Cause a Resolver to Crash when Validating Author: Michael McNally Reference Number: AA-01267 Views: 859 Created: 2015-06-16 19:57 Last Updated: 2015-07-07 18:15 0 Rating/ Voters An attacker who can cause a validating resolver to query a zone containing specifically constructed contents can cause that resolver to fail an assertion and terminate due to a defect in validation code. CVE: CVE-2015-4620 Document Version: 2.0 Posting date: 7 July 2015 Program Impacted: BIND Versions affected: BIND 9.7.1 -> 9.7.7, 9.8.0 -> 9.8.8, 9.9.0 -> 9.9.7, 9.10.0 -> 9.10.2-P1. Severity: Critical Exploitable: Remotely Description: A very uncommon combination of zone data has been found that triggers a bug in BIND, with the result that named will exit with a "REQUIRE" failure in name.c when validating the data returned in answer to a recursive query. This means that a recursive resolver that is performing DNSSEC validation can be deliberately stopped by an attacker who can cause the resolver to perform a query against a maliciously-constructed zone. Impact: A recursive resolver that is performing DNSSEC validation can be deliberately terminated by any attacker who can cause a query to be performed against a maliciously constructed zone. This will result in a denial of service to clients who rely on that resolver. DNSSEC validation is only performed by a recursive resolver if it has "dnssec-validation auto;" in its configuration or if it has a root trust anchor defined and has "dnssec-validation yes;" set (either by accepting the default or via an explicitly set value of "yes".) By default ISC BIND recursive servers will not validate. (However, ISC defaults may have been changed by your distributor.) 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: https://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:L/Au:N/C:N/I:N/A:C) Workarounds: Disabling DNSSEC validation prevents exploitation of this defect but is not generally recommended. The recommended solution is to upgrade to a patched version. Active exploits: There are no known active exploits at this time. Solution: Upgrade to the patched release most closely related to your current version of BIND: BIND 9 version 9.9.7-P1 BIND 9 version 9.10.2-P2 Acknowledgements: ISC would like to thank Breno Silveira Soares of Servio Federal de Processamento de Dados (SERPRO) for discovering and reporting this defect. Document Revision History: 1.0 Phase One: Advance Notification 23 June, 2015 1.1 Phase Two: Notification to BIND Packagers 29 June, 2015 1.2 Revised public release date (to 7 July 2015) and re-notified Phase One and Phase Two recipients: 30 June, 2015 2.0 Phase Three: Public Disclosure, 7 July 2015 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@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 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-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html This Knowledge Base article https://kb.isc.org/article/AA-01267 is the complete and official security advisory document. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBVZxp9n6ZAP0PgtI9AQIyQxAAho6vGDVddjmrUugAbOjQ8WbAoiiOAs3h SZR82Q6aGVNKU3kBLRoESMhP+EfgH0Mi6hfLkRjp6Ec2ciAb9yvEea3tK7xcP4bC 36aqfAtHH5CaTXedkE/alW/bD99Nt9vAI25dF6FwXsr4wgQhXMflSw/2OikFNjAk 3OWtn9Ptf5E+NbmfwCdUMwWuwMhhEH10xT2B6bRotrnjlQcp7p+RTQG0LAMaR8ze aIPbUn3MvfIen3MvDbEa10TMPZZI4TtP0fNtkDeoxqiCZctLR/zlBFLpWNGniITg tksOWuHRYpMU3EjHbaOYpQxG/HjEeXiNsdUqzTRErEIn0oWnhsCO3ztc5puoqPF5 7LmAeOMs1sa6TObavxU8p+BJ5ioi6gPe+wIVef9PEtoh1nE0sVKVjZ47rHKDCTYv 8ubsSZo4d/B4eZ6y3UXVmm+FAnEvrPM+ZbeGyLvS/K1JAr5DhPyyPOzAEgsAGbgx EKAOfylNb3OIbGbSshrifhDDeHqYQMcDfSwr7OctPbwulcRe1WLde7c468jBfBx2 GXbnB5IgUCIVhg5VVT33bO0mHbVcACvg5pQw0XRJ9pqMYVlOlXgJ/BBMkcOw+vCI fX3aYtI5+9zuyO92ASmpwpC5wfuZjGsB5DlY16jsHZLT3XUcdcwKf/mp2UxDK2Ju Oijz3Xy9OHo= =e7u/ -----END PGP SIGNATURE-----