IBM SECURITY ADVISORY First Issued: Thu Oct 5 10:43:28 CDT 2023 The most recent version of this document is available here: https://aix.software.ibm.com/aix/efixes/security/ntp_advisory14.asc Security Bulletin: AIX is vulnerable to a denial of service due to NTP (CVE-2023-26551, CVE-2023-26552, CVE-2023-26553, CVE-2023-26554) =============================================================================== SUMMARY: Multiple vulnerabilities in NTP could allow a remote attacker to cause a denial of service (CVE-2023-26551, CVE-2023-26552, CVE-2023-26553, CVE-2023-26554). =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2023-26551 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-26551 DESCRIPTION: NTP is vulnerable to a denial of service, caused by an out-of-bounds write in mstolfp in libntp/mstolfp.c. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service. CVSS Base Score: 5.3 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/252595 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:L) CVEID: CVE-2023-26552 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-26552 DESCRIPTION: NTP is vulnerable to a denial of service, caused by an out-of-bounds write in mstolfp in libntp/mstolfp.c. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service. CVSS Base Score: 5.3 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/252594 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:L) CVEID: CVE-2023-26553 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-26553 DESCRIPTION: NTP is vulnerable to a denial of service, caused by an out-of-bounds write in mstolfp in libntp/mstolfp.c. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service. CVSS Base Score: 5.3 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/252593 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:L) CVEID: CVE-2023-26554 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-26554 DESCRIPTION: NTP is vulnerable to a denial of service, caused by an out-of-bounds write in mstolfp in libntp/mstolfp.c. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service. CVSS Base Score: 5.3 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/252592 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:L) AFFECTED PRODUCTS AND VERSIONS: AIX 7.2, 7.3 VIOS 3.1 The vulnerabilities in the following filesets are being addressed: key_fileset = aix Fileset Lower Level Upper Level KEY --------------------------------------------------------- ntp.rte 7.4.2.8100 7.4.2.8153 key_w_fs ntp.rte 73.4.2.8151 73.4.2.8154 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 ntp.rte REMEDIATION: A. APARS IBM has assigned the following APARs to this problem: AIX Level APAR Availability SP KEY ----------------------------------------------------- 7.2 IJ47973 ** N/A key_w_apar 7.3 IJ47974 ** N/A key_w_apar VIOS Level APAR Availability SP KEY ----------------------------------------------------- 3.1 IJ47973 ** N/A key_w_apar Subscribe to the APARs here: https://www.ibm.com/support/pages/apar/[APAR Number] 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. AIX and VIOS fixes are available. The fixes are cumulative and address previously issued AIX/VIOS NTP security bulletins with respect to fileset level. The AIX and VIOS fixes can be downloaded via https from: https://aix.software.ibm.com/aix/efixes/security/ntp_fix14.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 IJ47973s6a.230829.epkg.Z key_w_fix 7.3 IJ47974s4a.230829.epkg.Z key_w_fix VIOS Level Interim Fix (*.Z) KEY ----------------------------------------------- 3.1 IJ47973s6a.230829.epkg.Z key_w_fix To extract the fixes from the tar file: tar xvf ntp_fix14.tar cd ntp_fix14 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 ----------------------------------------------------------------------------------------------------- f79d53ff1de803f3ee2d30e5cd9bf6082559a26e27cc18706877e114c46bbb68 IJ47973s6a.230829.epkg.Z key_w_csum 5eba38fa620746c76c6fa6ba249d2dfced28fbabafc4042789908eda2dbe9dff IJ47974s4a.230829.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/ntp_advisory14.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/ntp_advisory14.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 a denial of service due to NTP (CVE-2023-26551, CVE-2023-26552, CVE-2023-26553, CVE-2023-26554) https://www.ibm.com/support/pages/node/7047270 ACKNOWLEDGEMENTS: None. CHANGE HISTORY: First Issued: Thu Oct 5 10:43:28 CDT 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.