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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.1408 Multiple vulnerabilities have been identified in BIND 26 April 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIND Publisher: ISC Operating System: UNIX variants (UNIX, Linux, OSX) Windows Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2019-6468 CVE-2019-6467 CVE-2018-5743 Reference: ESB-2019.1405 Original Bulletin: https://kb.isc.org/docs/cve-2018-5743 https://kb.isc.org/docs/cve-2019-6467 https://kb.isc.org/docs/cve-2019-6468 Comment: This bulletin contains three (3) ISC security advisories. - --------------------------BEGIN INCLUDED TEXT-------------------- CVE: CVE-2018-5743 Document version: 2.0 Posting date: 24 April 2019 Program impacted: BIND Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.6, 9.12.0 -> 9.12.4, 9.14.0. BIND 9 Supported Preview Edition versions 9.9.3-S1 -> 9.11.5-S3, and 9.11.5-S5. Versions 9.13.0 -> 9.13.7 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5743. Severity: High Exploitable: Remotely Description: By design, BIND is intended to limit the number of TCP clients that can be connected at any given time. The number of allowed connections is a tunable parameter which, if unset, defaults to a conservative value for most servers. Unfortunately, the code which was intended to limit the number of simultaneous connections contains an error which can be exploited to grow the number of simultaneous connections beyond this limit. Impact: By exploiting the failure to limit simultaneous TCP connections, an attacker can deliberately exhaust the pool of file descriptors available to named, potentially affecting network connections and the management of files such as log files or zone journal files. In cases where the named process is not limited by OS-enforced per-process limits, this could additionally potentially lead to exhaustion of all available free file descriptors on that system. 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: None. Active exploits: No known deliberate exploits, but the situation may occur accidentally on busy servers. It is possible for operators to mistakenly believe that their configured (or default) limit is sufficient for their typical operations, when in fact it is not. Following an upgrade to a version that effectively applies limits, named may deny connections which were previously improperly permitted. Operators can monitor their logs for rejected connections, keep an eye on "rndc status" reports of simultaneous connections, or use other tools to monitor whether the now-effective limits are causing problems for legitimate clients. Should this be the case, increasing the value of the tcp-clients setting in named.conf to an appropriate value would be recommended. Solution: Upgrade to a version of BIND containing a fix for the ineffective limits. - BIND 9.11.6-P1 - BIND 9.12.4-P1 - BIND 9.14.1 BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. - BIND 9.11.5-S6 - BIND 9.11.6-S1 Acknowledgements: ISC would like to thank AT&T for helping us to discover this issue. Document revision history: 1.0 Advance Notification, 16 January 2019 1.1 Recall due to error in original fix, 17 January 2019 1.3 Replacement fix delivered to Advance Notification customers, 15 April 2019 1.4 Corrected Versions affected and Solution, 16 April 2019 1.5 Added reference to BIND 9.11.6-S1 2.0 Public disclosure, 24 April 2019 Related documents: See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected. 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 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. 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. - --- CVE: CVE-2019-6467 Document version: 2.0 Posting date: 24 April 2019 Program impacted: BIND Versions affected: BIND 9.12.0-> 9.12.4, 9.14.0. Also affects all releases in the 9.13 development branch. Severity: Medium Exploitable: Remotely Description: A programming error in the nxdomain-redirect feature can cause an assertion failure in query.c if the alternate namespace used by nxdomain-redirect is a descendant of a zone that is served locally. The most likely scenario where this might occur is if the server, in addition to performing NXDOMAIN redirection for recursive clients, is also serving a local copy of the root zone or using mirroring to provide the root zone, although other configurations are also possible. Impact: An attacker who can deliberately trigger the condition on a server with a vulnerable configuration can cause BIND to exit, denying service to other clients. CVSS Score: 5.9 CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H. Workarounds: Exploitation of this defect can be effectively prevented by disabling the nxdomain-redirect feature in the nameserver's configuration. Active exploits: None known. Solution: Upgrade to the patched release most closely related to your current version of BIND: - BIND 9.12.4-P1 - BIND 9.14.1 Document revision history: 1.0 Early Notification, 15 April 2019 1.1 Removed BIND 9.11.6-P1 from Solution version list 2.0 Public Disclosure, 24 April 2019 Related documents: See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected. 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 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. 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. - --- CVE: CVE-2019-6468 Document version: 2.0 Posting date: 24 April 2019 Program impacted: BIND Versions affected: BIND Supported Preview Edition version 9.10.5-S1 -> 9.11.5-S5. ONLY BIND Supported Preview Edition releases are affected. Severity: Medium Exploitable: Remotely Description: In BIND Supported Preview Edition, an error in the nxdomain-redirect feature can occur in versions which support EDNS Client Subnet (ECS) features. In those versions which have ECS support, enabling nxdomain-redirect is likely to lead to BIND exiting due to assertion failure. Impact: If nxdomain-redirect is enabled (via configuration) in a vulnerable BIND release, a malicious party can cause BIND to exit by deliberately triggering the bug. CVSS Score: 5.9 CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N 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:H/PR:N/UI:N/S:U/C:N/I:N/A:H. Workarounds: Exploitation of this defect can be effectively prevented by disabling the nxdomain-redirect feature in the nameserver's configuration. Active exploits: None known. Solution: Upgrade to the patched release most closely related to your current version of BIND: BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. - BIND 9.11.5-S6 - BIND 9.11.6-S1 Document revision history: 1.0 Early Notification, 15 April 2019 1.1 Added reference to BIND 9.11.6-S1 in Solution section 2.0 Public Disclosure, 24 April 2019 Related documents: See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected. 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 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. 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. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXMJLU2aOgq3Tt24GAQiBrBAAnCFrKMuX2OmClmaBRVQSHeU82J/iqmV0 Ue4W4pHUmIPSn872yPplivwfwUDOU1THHwsWtzCeH89/oQfGBe2SKFfjygpkgR+T qQalBwJY1zCB85jb3/ibjab3/c+wnRopM1QfwAfj42JJTs4YcUQkoCB3pY4Qo7nn uiwlnb9/l/YoIaDrA7cGUG9d6VE6+uK+EksoxF0raarBEP+I6Qi0ElHWiELufGrz kW68kJbiYKTnfa6vll1WFK8TeC/THnVzOCM00e381QpQpDujgrTdW8LDx4YtxOxL O5JaM7+LQBHC4tktasac7MTKw3bg63OAJx2lhcXNgHV+5rnPjR4WJJxXxFhh5flr ev6kLcAWWGzZO0Ox/Un4IJBBCKHAvT7pdqIHqduu6l5nTwwQENx6YxNroDXZCcRB xCG4WSwB+0TxDog8Y00eEDAXIjAshPR9uMmg0JgWE/AHJzkK0OWa5fEtULKlcmRp 0CoyTFweQuvgK4rpDM+muZK8tyEejKhHEfZ9jQmpXRDTIIa7aQn8FWixqCU4pvjj hMiYtBX637KJq3IeMgCLa67Cx2GwsyB/x7x1IbTjEMY6yuB+X7HFpUIct4onIy2A ioOWA3YrwMHSWzFeeCO04+jGGKAYASqooxq2Y79fBVfn95RxlnL2n8LofRLyz810 4wI4RTdAWIg= =vX5P -----END PGP SIGNATURE-----