===================================================================== CERT-Renater Note d'Information No. 2023/VULN232 _____________________________________________________________________ DATE : 23/06/2023 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running BIND versions prior to 9.16.42, 9.18.16, 9.19.14, 9.16.42-S1, 9.18.16-S1. ===================================================================== https://kb.isc.org/docs/cve-2023-2828 https://kb.isc.org/docs/cve-2023-2829 https://kb.isc.org/docs/cve-2023-2911 _____________________________________________________________________ CVE-2023-2828: named's configured cache size limit can be significantly exceeded Updated on 21 Jun 2023 CVE: CVE-2023-2828 Document version: 2.0 Posting date: 21 June 2023 Program impacted: BIND 9 Versions affected: BIND 9.11.0 -> 9.16.41 9.18.0 -> 9.18.15 9.19.0 -> 9.19.13 BIND Supported Preview Edition 9.11.3-S1 -> 9.16.41-S1 9.18.11-S1 -> 9.18.15-S1 (Versions prior to 9.11.37 & 9.11.37-S1 were not assessed, but we believe that all versions of BIND 9.11 are vulnerable. Some even older major branches may be vulnerable as well.) Severity: High Exploitable: Remotely Description: Every named instance configured to run as a recursive resolver maintains a cache database holding the responses to the queries it has recently sent to authoritative servers. The size limit for that cache database can be configured using the max-cache-size statement in the configuration file; it defaults to 90% of the total amount of memory available on the host. When the size of the cache reaches 7/8 of the configured limit, a cache-cleaning algorithm starts to remove expired and/or least-recently used RRsets from the cache, to keep memory use below the configured limit. It has been discovered that the effectiveness of the cache-cleaning algorithm used in named can be severely diminished by querying the resolver for specific RRsets in a certain order, effectively allowing the configured max-cache-size limit to be significantly exceeded. Impact: By exploiting this flaw, an attacker can cause the amount of memory used by a named resolver to go well beyond the configured max-cache-size limit. The effectiveness of the attack depends on a number of factors (e.g. query load, query patterns), but since the default value of the max-cache-size statement is 90%, in the worst case the attacker can exhaust all available memory on the host running named, leading to a denial-of-service condition. CVSS Score: 7.5 CVSS Vector: CVSS:3.1/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://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1. Workarounds: No workarounds known. Active exploits: We are not aware of any active exploits. Solution: Upgrade to the patched release most closely related to your current version of BIND 9: 9.16.42 9.18.16 9.19.14 BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. 9.16.42-S1 9.18.16-S1 Acknowledgments: ISC would like to thank Shoham Danino from Reichman University, Anat Bremler-Barr from Tel-Aviv University, Yehuda Afek from Tel-Aviv University, and Yuval Shavitt from Tel-Aviv University for bringing this vulnerability to our attention. Document revision history: 1.0 Early Notification, 14 June 2023 2.0 Public disclosure, 21 June 2023 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 be mailed 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/pgpkey/. If you are unable to use encrypted email you may also report new issues at: https://www.isc.org/reportbug/. 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/download/. 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 at https://kb.isc.org/docs/aa-00861. The Knowledgebase article https://kb.isc.org/docs/cve-2023-2828 is the complete and official security advisory document. 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-2023-2829: Malformed NSEC records can cause named to terminate unexpectedly when synth-from-dnssec is enabled Updated on 21 Jun 2023 CVE: CVE-2023-2829 Document version: 2.0 Posting date: 21 June 2023 Program impacted: BIND 9 Versions affected: BIND Supported Preview Edition 9.16.8-S1 -> 9.16.41-S1 9.18.11-S1 -> 9.18.15-S1 Severity: High Exploitable: Remotely Description: A named instance configured to run as a DNSSEC-validating recursive resolver with the Aggressive Use of DNSSEC-Validated Cache (RFC 8198) option (synth-from-dnssec) enabled can be remotely terminated using a zone with a malformed NSEC record. Impact: By sending specific queries to the resolver, an attacker can cause named to terminate unexpectedly. Note that the BIND configuration option synth-from-dnssec is enabled by default in all versions of BIND 9.18 and 9.18-S and newer. In earlier versions of BIND that had this option available, it was disabled unless activated explicitly in named.conf. CVSS Score: 7.5 CVSS Vector: CVSS:3.1/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://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1. Workarounds: Setting synth-from-dnssec to no prevents the problem. Active exploits: We are not aware of any active exploits. Solution: Upgrade to the patched release most closely related to your current version of BIND 9: BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. 9.16.42-S1 9.18.16-S1 Acknowledgments: ISC would like to thank Greg Kuechle from SaskTel for bringing this vulnerability to our attention. Document revision history: 1.0 Early Notification, 14 June 2023 2.0 Public disclosure, 21 June 2023 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 be mailed 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/pgpkey/. If you are unable to use encrypted email you may also report new issues at: https://www.isc.org/reportbug/. 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/download/. 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 at https://kb.isc.org/docs/aa-00861. The Knowledgebase article https://kb.isc.org/docs/cve-2023-2829 is the complete and official security advisory document. 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-2023-2911: Exceeding the recursive-clients quota may cause named to terminate unexpectedly when stale-answer-client-timeout is set to 0 Updated on 21 Jun 2023 CVE: CVE-2023-2911 Document version: 2.0 Posting date: 21 June 2023 Program impacted: BIND 9 Versions affected: BIND 9.16.33 -> 9.16.41 9.18.7 -> 9.18.15 BIND Supported Preview Edition 9.16.33-S1 -> 9.16.41-S1 9.18.11-S1 -> 9.18.15-S1 (BIND 9.11-S versions that support the stale-answer-client-timeout option are not vulnerable.) Severity: High Exploitable: Remotely Description: If the recursive-clients quota is reached on a BIND 9 resolver configured with both stale-answer-enable yes; and stale-answer-client-timeout 0;, a sequence of serve-stale-related lookups could cause named to loop and terminate unexpectedly due to a stack overflow. Impact: By sending specific queries to the resolver, an attacker can cause named to terminate unexpectedly. CVSS Score: 7.5 CVSS Vector: CVSS:3.1/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://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1. Workarounds: Setting stale-answer-client-timeout to off or to a non-zero value prevents the issue. Users of versions 9.18.10, 9.16.36, 9.16.36-S1 or older who are unable to upgrade should set stale-answer-client-timeout to off; using a non-zero value with these older versions leaves named vulnerable to CVE-2022-3924. Although it is possible to set the recursive-clients limit to a high number to reduce the likelihood of this scenario, this is not recommended; the limit on recursive-clients is important for preventing exhaustion of server resources. The limit cannot be disabled entirely. Active exploits: This flaw was discovered in internal testing. We are not aware of any active exploits. Solution: Upgrade to the patched release most closely related to your current version of BIND 9: 9.16.42 9.18.16 BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. 9.16.42-S1 9.18.16-S1 Document revision history: 1.0 Early Notification, 14 June 2023 2.0 Public disclosure, 21 June 2023 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 be mailed 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/pgpkey/. If you are unable to use encrypted email you may also report new issues at: https://www.isc.org/reportbug/. 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/download/. 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 at https://kb.isc.org/docs/aa-00861. The Knowledgebase article https://kb.isc.org/docs/cve-2023-2911 is the complete and official security advisory document. 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. ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 23/25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email:cert@support.renater.fr + =========================================================