IBM SECURITY ADVISORY First Issued: Mon Dec 18 09:19:46 CST 2023 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/bind_advisory25.asc Security Bulletin: AIX is vulnerable to denial of service due to ISC BIND (CVE-2023-3341) =============================================================================== SUMMARY: A vulnerability in ISC BIND could allow a remote attacker to cause a denial of service (CVE-2023-3341) AIX uses ISC BIND as part of its DNS functions. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2023-3341 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-3341 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a stack exhaustion flaw in control channel code. By sending a specially crafted message over the control channel, a remote attacker could exploit this vulnerability to cause named to terminate. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/266515 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 ---------------------------------------------------------- bos.net.tcp.bind 7.2.5.100 7.2.5.101 key_w_fs bos.net.tcp.bind 7.2.5.200 7.2.5.200 key_w_fs bind.rte 7.1.916.0 7.1.916.2603 key_w_fs bind.rte 7.3.916.0 7.3.916.2600 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 bos.net.tcp.bind REMEDIATION: A. APARS IBM has assigned the following APARs to this problem: AIX Level APAR Availability SP KEY ----------------------------------------------------- 7.2.5 IJ49093 ** SP08 key_w_apar VIOS Level APAR Availability SP KEY ----------------------------------------------------- 3.1.3 IJ49094 ** N/A key_w_apar 3.1.4 IJ49093 ** 3.1.4.40 key_w_apar Subscribe to the APARs here: https://www.ibm.com/support/pages/apar/IJ49093 https://www.ibm.com/support/pages/apar/IJ49094 By subscribing, you will receive periodic email alerting you to the status of the APAR, and a link to download the fix once it becomes available. B. FIXES IBM strongly recommends addressing the vulnerability now. For bind.rte on 7.3 and if installed on 7.2 TL5, remediation is a new fileset that is available for download from: https://www.ibm.com/resources/mrs/assets?source=aixbp AIX and VIOS iFixes are available for AIX 7.2 TL5 and VIO 3.1. The fixes are cumulative and address previously issued AIX/VIOS BIND security bulletins with respect to SP and TL. The AIX and VIOS fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/bind_fix25.tar The link above is to a tar file containing this signed advisory, fix 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. AIX Level Interim Fix (*.Z) KEY --------------------------------------------- 7.2.5.5 IJ44424s5.221129.epkg.Z key_w_fix 7.2.5.5 IJ49093s7.231109.epkg.Z key_w_fix 7.2.5.6 IJ49093s7.231109.epkg.Z key_w_fix 7.2.5.7 IJ49093s7.231109.epkg.Z key_w_fix Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.5.6 is AIX 7200-05-06. Note: Two iFixes are provided for AIX 7.2 TL5 SP5 and required if the relevant filesets are installed. IJ44424s5 is for the bos.net.tcp.bind_utils fileset. IJ49093s7 is for the bos.net.tcp.bind fileset. Please reference the Affected Products and Version section above for help with checking installed fileset levels. VIOS Level Interim Fix (*.Z) KEY ---------------------------------------------- 3.1.3.21 IJ44424s5.221129.epkg.Z key_w_fix 3.1.3.21 IJ49094s4.231110.epkg.Z key_w_fix 3.1.3.30 IJ44424s5.221129.epkg.Z key_w_fix 3.1.3.30 IJ49094s4.231110.epkg.Z key_w_fix 3.1.3.40 IJ49094s4.231110.epkg.Z key_w_fix 3.1.4.10 IJ44424s5.221129.epkg.Z key_w_fix 3.1.4.10 IJ49093s7.231109.epkg.Z key_w_fix 3.1.4.21 IJ49093s7.231109.epkg.Z key_w_fix 3.1.4.31 IJ49093s7.231109.epkg.Z key_w_fix Note: Two iFixes are provided for: VIOS 3.1.3.21, 3.1.3.30 VIOS 3.1.4.10 Both iFixes are required if the relevant filesets are installed. IJ44424s5 is for the bos.net.tcp.bind_utils fileset. IJ49093s7 is for the bos.net.tcp.bind fileset. To extract the fixes from the tar file: tar xvf bind_fix25.tar cd bind_fix25 Verify you have retrieved the fixes intact: The checksums below were generated using the "openssl dgst -sha256 [filename]" command as the following: openssl dgst -sha256 filename KEY ----------------------------------------------------------------------------------------------------- af0073ada814a0d8bbf219761175c8e889c8a1422cb5a5f37b6ca47192cca91b IJ44424s5.221129.epkg.Z key_w_csum 7c7f99d2df4876f43d0868b4deda27df7bcdcb89d61ce5282f593001ae845c0e IJ49093s7.231109.epkg.Z key_w_csum 1cb19ec13c7ce95a402be4ac2a63cc27dbcf395468a17d73c6d33fdfb645464b IJ49094s4.231110.epkg.Z key_w_csum a773584176f0467a241a06e69764f0b74fe018c75f48ffaf0359c30464dd038f IJ49095s6.231110.epkg.Z 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_advisory25.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: ftp://ftp.software.ibm.com/systems/power/AIX/systems_p_os_aix_security_pubkey.txt 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_advisory25.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 (CVE-2023-3341) https://www.ibm.com/support/pages/node/7099313 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Mon Dec 18 09:19:46 CST 2023 =============================================================================== *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.