IBM SECURITY ADVISORY First Issued: Tue Jun 4 16:06:25 CDT 2024 |Updated: Wed Jun 5 08:17:08 CDT 2024 |Update: Corrected the affected fileset levels to reflect that | bind.rte 7.1.916.2604 and 7.3.916.2601 are vulnerable. The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/bind_advisory26.asc Security Bulletin: AIX is vulnerable to denial of service due to ISC BIND =============================================================================== SUMMARY: Multiple vulnerabilities in ISC BIND could allow a remote attacker to cause a denial of service. AIX uses ISC BIND as part of its DNS functions. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2023-50868 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-50868 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an error when preparing an NSEC3 closest encloser proof. By flooding the target resolver with queries, a remote attacker could exploit this vulnerability to cause CPU exhaustion on a DNSSEC-validating resolver. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/282901 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2023-50387 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-50387 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an error when processing responses coming from specially crafted DNSSEC-signed zones. By flooding the target server with queries, a remote attacker could exploit this vulnerability to cause CPU exhaustion on a DNSSEC-validating resolver. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/281081 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2023-4408 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4408 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an error when parsing large DNS messages. By flooding the target server with queries, a remote attacker could exploit this vulnerability to cause excessive CPU load. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/282906 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2023-6516 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-6516 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an out-of-memory condition. By using specific recursive query patterns, a remote attacker could exploit this vulnerability to cause the amount of memory used by a named resolver to go well beyond the configured max-cache-size limit, leading to a denial of service. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/282902 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2023-5679 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-5679 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an error when enabling both DNS64 and serve-stale. By querying a DNS64-enabled resolver for domain names triggering serve-stale, a remote attacker could exploit this vulnerability to trigger an assertion failure. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/282904 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) CVEID: CVE-2023-5517 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-5517 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a flaw in query-handling code. By querying RFC 1918 reverse zones, a remote attacker could exploit this vulnerability to trigger an assertion failure. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/282905 for the current score CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 3.1, 4.1 The following fileset levels are vulnerable: key_fileset = aix Fileset Lower Level Upper Level KEY ---------------------------------------------------------- bind.rte 7.1.916.0 7.1.916.2604 key_w_fs bind.rte 7.2.916.0 7.2.916.2600 key_w_fs bind.rte 7.3.916.0 7.3.916.2601 key_w_fs To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user's guide. Example: lslpp -L | grep -i bind.rte REMEDIATION: A. FIXES IBM strongly recommends addressing the vulnerability now. The AIX and VIOS fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/bind_fix26.tar The link above is to a tar file containing this signed advisory, install packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels. To extract the fixes from the tar file: tar xvf bind_fix26.tar For AIX 7.2 and VIOS 3.1 with OpenSSL 1.0 installed: tar xvf bind_fix26/71bind916.tar For AIX 7.2 and VIOS 3.1 with OpenSSL 1.1 installed: tar xvf bind_fix26/72bind916.tar For AIX 7.3 and VIOS 4.1: tar xvf bind_fix26/73bind916.tar IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. To preview the fix installation: installp -apYd . bind To install the fix package: installp -aXYd . bind Verify you have retrieved the fixes intact: The checksums below were generated using the "openssl dgst -sha256 [file]" command as the following: openssl dgst -sha256 filename KEY --------------------------------------------------------------------------------------- 1a44cbf3ada06c29efdaad7757ab248995e0623689a5ca8682e4c610cd127364 71bind.rte key_w_csum 4016a2ffafda43b8deb9039dd6736a1b9bf3eb11afba0889041ae2e00dec5237 72bind.rte key_w_csum 4ed621e5f8957739023e370e04ef58bf38ee96489c6ba0f54181b40bcf239b8c 73bind.rte key_w_csum These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes. If the sums or signatures cannot be confirmed, contact IBM Support at http://ibm.com/support/ and describe the discrepancy. openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file] openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file] Published advisory OpenSSL signature file location: https://aix.software.ibm.com/aix/efixes/security/bind_advisory26.asc.sig C. FIX AND INTERIM FIX INSTALLATION If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. To preview a fix installation: installp -a -d fix_name -p all # where fix_name is the name of the # fix package being previewed. To install a fix package: installp -a -d fix_name -X all # where fix_name is the name of the # fix package being installed. Interim fixes have had limited functional and regression testing but not the full regression testing that takes place for Service Packs; however, IBM does fully support them. Interim fix management documentation can be found at: https://www.ibm.com/support/pages/managing-interim-fixes-aix To preview an interim fix installation: emgr -e ipkg_name -p # where ipkg_name is the name of the # interim fix package being previewed. To install an interim fix package: emgr -e ipkg_name -X # where ipkg_name is the name of the # interim fix package being installed. WORKAROUNDS AND MITIGATIONS: None. =============================================================================== CONTACT US: Note: Keywords labeled as KEY in this document are used for parsing purposes. If you would like to receive AIX Security Advisories via email, please visit "My Notifications": https://www.ibm.com/support/mynotifications Contact IBM Support for questions related to this announcement: https://ibm.com/support/ For information on how to securely verify AIX security bulletins and fixes: https://www.ibm.com/support/pages/node/6985269 To obtain the OpenSSL public key that can be used to verify the signed advisories and ifixes: Download the key from our web page: https://aix.software.ibm.com/aix/efixes/security/systems_p_os_aix_security_pubkey.txt To verify the AIX/VIOS security bulletin: Published advisory OpenSSL signature file location: https://aix.software.ibm.com/aix/efixes/security/bind_advisory26.asc.sig openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file] Please contact your local IBM AIX support center for any assistance. REFERENCES: Complete CVSS v3 Guide: http://www.first.org/cvss/user-guide On-line Calculator v3: http://www.first.org/cvss/calculator/3.0 RELATED INFORMATION: IBM Secure Engineering Web Portal http://www.ibm.com/security/secure-engineering/bulletins.html IBM Product Security Incident Response Blog https://www.ibm.com/blogs/psirt/ Security Bulletin: AIX is vulnerable to denial of service due to ISC BIND https://www.ibm.com/support/pages/node/7156443 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Tue Jun 4 16:06:25 CDT 2024 | Updated: Wed Jun 5 08:17:08 CDT 2024 | Update: Corrected the affected fileset levels to reflect that | bind.rte 7.1.916.2604 and 7.3.916.2601 are vulnerable. =============================================================================== *The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin. Disclaimer According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.