IBM SECURITY ADVISORY First Issued: Thu Jul 29 15:13:19 CDT 2021 The most recent version of this document is available here: http://aix.software.ibm.com/aix/efixes/security/bind_advisory19.asc https://aix.software.ibm.com/aix/efixes/security/bind_advisory19.asc ftp://aix.software.ibm.com/aix/efixes/security/bind_advisory19.asc Security Bulletin: Vulnerability in BIND affects AIX (CVE-2021-25215) =============================================================================== SUMMARY: There is a vulnerability in BIND that affects AIX. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2021-25215 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-25215 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-25215 DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by an assertion failure while answering queries for DNAME records. By sending a query for DNAME records, an attacker could exploit this vulnerability to trigger a failed assertion check and terminate the named process. CVSS Base Score: 7.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/200960 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 7.1, 7.2 VIOS 3.1 The following fileset levels are vulnerable: key_fileset = aix Fileset Lower Level Upper Level KEY --------------------------------------------------------- bos.net.tcp.server 7.1.5.0 7.1.5.34 key_w_fs bos.net.tcp.bind 7.2.3.0 7.2.3.15 key_w_fs bos.net.tcp.bind 7.2.4.0 7.2.4.0 key_w_fs bos.net.tcp.bind 7.2.5.0 7.2.5.1 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.server REMEDIATION: A. APARS IBM has assigned the following APARs to this problem: AIX Level APAR Availability SP KEY ----------------------------------------------------- 7.1.5 IJ33276 ** SP09 key_w_apar 7.2.3 IJ33277 ** N/A key_w_apar 7.2.4 IJ33278 ** SP05 key_w_apar 7.2.5 IJ33280 ** SP03 key_w_apar VIOS Level APAR Availability SP KEY ----------------------------------------------------- 3.1.0 IJ33277 ** N/A key_w_apar 3.1.1 IJ33278 ** 3.1.1.50 key_w_apar 3.1.2 IJ33279 ** 3.1.2.30 key_w_apar Subscribe to the APARs here: http://www.ibm.com/support/pages/apar/IJ33276 http://www.ibm.com/support/pages/apar/IJ33277 http://www.ibm.com/support/pages/apar/IJ33278 http://www.ibm.com/support/pages/apar/IJ33279 http://www.ibm.com/support/pages/apar/IJ33280 https://www.ibm.com/support/pages/apar/IJ33276 https://www.ibm.com/support/pages/apar/IJ33277 https://www.ibm.com/support/pages/apar/IJ33278 https://www.ibm.com/support/pages/apar/IJ33279 https://www.ibm.com/support/pages/apar/IJ33280 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 AIX and VIOS fixes are available. The AIX and VIOS fixes can be downloaded via ftp or http from: ftp://aix.software.ibm.com/aix/efixes/security/bind_fix19.tar http://aix.software.ibm.com/aix/efixes/security/bind_fix19.tar https://aix.software.ibm.com/aix/efixes/security/bind_fix19.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 ---------------------------------------------- 7.1.5.6 IJ33276s8a.210622.epkg.Z key_w_fix 7.1.5.7 IJ33276s8a.210622.epkg.Z key_w_fix 7.1.5.8 IJ33276s8a.210622.epkg.Z key_w_fix 7.2.3.5 IJ33277s7a.210622.epkg.Z key_w_fix 7.2.3.6 IJ33277s7a.210622.epkg.Z key_w_fix 7.2.3.7 IJ33277s7a.210622.epkg.Z key_w_fix 7.2.4.2 IJ33278s4a.210622.epkg.Z key_w_fix 7.2.4.3 IJ33278s4a.210622.epkg.Z key_w_fix 7.2.4.4 IJ33278s4a.210622.epkg.Z key_w_fix 7.2.5.0 IJ33279s2a.210621.epkg.Z key_w_fix 7.2.5.1 IJ33279s2a.210621.epkg.Z key_w_fix 7.2.5.2 IJ33279s2a.210621.epkg.Z key_w_fix Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.3.5 is AIX 7200-03-05. Please reference the Affected Products and Version section above for help with checking installed fileset levels. VIOS Level Interim Fix (*.Z) KEY ----------------------------------------------- 3.1.0.40 IJ33277s7a.210622.epkg.Z key_w_fix 3.1.0.50 IJ33277s7a.210622.epkg.Z key_w_fix 3.1.0.60 IJ33277s7a.210622.epkg.Z key_w_fix 3.1.1.20 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.1.21 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.1.22 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.1.25 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.1.30 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.1.40 IJ33278s4a.210622.epkg.Z key_w_fix 3.1.2.0 IJ33279s2a.210621.epkg.Z key_w_fix 3.1.2.10 IJ33279s2a.210621.epkg.Z key_w_fix 3.1.2.20 IJ33279s2a.210621.epkg.Z key_w_fix 3.1.2.21 IJ33279s2a.210621.epkg.Z key_w_fix The above fixes are cumulative and address previously issued AIX/VIOS BIND security bulletins with respect to /usr/sbin/named9. For full AIX/VIOS BIND remediation, the above fixes should be installed alongside the fixes issued with: https://aix.software.ibm.com/aix/efixes/security/bind_advisory18.asc https://www.ibm.com/support/pages/node/6388720 To extract the fixes from the tar file: tar xvf bind_fix19.tar cd bind_fix19 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 ----------------------------------------------------------------------------------------------------- 702bbfdaddeaa2a4b1e83be581ce1e07a98de4d26754efa3abf6b409430f542e IJ33276s8a.210622.epkg.Z key_w_csum b54833729d51873682abf944dccb8ff79e67014efe6201f8703cf8dd389211f3 IJ33277s7a.210622.epkg.Z key_w_csum 63c2884898cf1c01ad3b0ff5f19120724e326cc9fa53020f51968f254f719c51 IJ33278s4a.210622.epkg.Z key_w_csum eacc45c120db7565be64808c7c9a29873a115837ff6863e6533646ac00a0e773 IJ33279s2a.210621.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: http://aix.software.ibm.com/aix/efixes/security/bind_advisory19.asc.sig https://aix.software.ibm.com/aix/efixes/security/bind_advisory19.asc.sig ftp://aix.software.ibm.com/aix/efixes/security/bind_advisory19.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: http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html 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": http://www.ibm.com/support/mynotifications To view previously issued advisories, please visit: http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq Contact IBM Support for questions related to this announcement: http://ibm.com/support/ https://ibm.com/support/ 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 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: Vulnerability in BIND affects AIX (CVE-2021-25215) https://www.ibm.com/support/pages/node/6476802 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Thu Jul 29 15:13:19 CDT 2021 =============================================================================== *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.