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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2023.1718 Cisco Adaptive Security Appliance Software, Firepower Threat Defense Software, IOS Software, and IOS XE Software IPv6 DHCP (DHCPv6) Client Denial of Service Vulnerability 23 March 2023 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Adaptive Security Appliance Software Firepower Threat Defense Software IOS Software IOS XE Software IPv6 DHCP (DHCPv6) Publisher: Cisco Systems Operating System: Cisco Resolution: Patch/Upgrade CVE Names: CVE-2023-20081 Original Bulletin: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftdios-dhcpv6-cli-Zf3zTv Comment: CVSS (Max): 6.8 CVE-2023-20081 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H) CVSS Source: Cisco Systems Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco Adaptive Security Appliance Software, Firepower Threat Defense Software, IOS Software, and IOS XE Software IPv6 DHCP (DHCPv6) Client Denial of Service Vulnerability Priority: Medium Advisory ID: cisco-sa-asaftdios-dhcpv6-cli-Zf3zTv First Published: 2023 March 22 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCwa34291 CSCwa34310 CVE Names: CVE-2023-20081 Summary o A vulnerability in the IPv6 DHCP (DHCPv6) client module of Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense (FTD) Software, Cisco IOS Software, and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient validation of DHCPv6 messages. An attacker could exploit this vulnerability by sending crafted DHCPv6 messages to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To successfully exploit this vulnerability, the attacker would need to either control the DHCPv6 server or be in a man-in-the-middle position. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftdios-dhcpv6-cli-Zf3zTv This advisory is part of the March 2023 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2023 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication . Affected Products o Vulnerable Products At the time of publication, this vulnerability affected the following Cisco products if they had the DHCPv6 client feature enabled: ASA Software FTD Software IOS Software IOS XE Software For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information. Determine the DHCPv6 Client Configuration To determine the DHCPv6 client configuration, use the show running-config CLI command. In the output, look for interfaces that have both the ipv6 enable command and the ipv6 address dhcp command. If there is at least one interface that has both IPv6 enabled and the DHCPv6 client feature enabled, the device is affected by this vulnerability. The following example shows the output of the show running-config command on a device that has both IPv6 and the DHCPv6 client feature enabled under interface GigabitEthernet0/0: firewall# show running-config interface GigabitEthernet0/0 ipv6 address dhcp ipv6 enable Note: On devices that are running Cisco IOS or IOS XE Software, also look for the ipv6 unicast-routing command in global configuration mode. If this command is missing, the devices are not processing any IPv6 traffic and are not affected, even if they have IPv6 and the DHCPv6 client feature enabled under any interface. Products Confirmed Not Vulnerable Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability. Cisco has confirmed that this vulnerability does not affect the following Cisco products: Firepower Management Center (FMC) Software FXOS Software IOS XR Software Meraki products Next-Generation Intrusion Prevention System (NGIPS) Software NX-OS Software Workarounds o There are no workarounds that address this vulnerability. Fixed Software o When considering software upgrades , customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page , to determine exposure and a complete upgrade solution. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers. Cisco ASA, FMC, and FTD Software To help customers determine their exposure to vulnerabilities in Cisco ASA, FMC, and FTD Software, Cisco provides the Cisco Software Checker . This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory ("First Fixed"). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies ("Combined First Fixed"). To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps: 1. Choose which advisories the tool will search-all advisories, only advisories with a Critical or High Security Impact Rating (SIR) , or only this advisory. 2. Choose the appropriate software. 3. Choose the appropriate platform. 4. Enter a release number-for example, 9.16.2.11 for Cisco ASA Software or 6.6.7 for Cisco FTD Software. 5. Click Check . Additional Resources For help determining the best Cisco ASA, FTD, or FMC Software release, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance. Cisco ASA Compatibility Cisco Secure Firewall ASA Upgrade Guide Cisco Secure Firewall Threat Defense Compatibility Guide Cisco IOS and IOS XE Software To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides the Cisco Software Checker . This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory ("First Fixed"). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies ("Combined First Fixed"). To use the tool, go to the Cisco Software Checker page and follow the instructions. Alternatively, use the following form to determine whether a release is affected by any Cisco Security Advisory. To use the form, follow these steps: 1. Choose which advisories the tool will search-only this advisory, only advisories with a Critical or High Security Impact Rating (SIR) , or all advisories. 2. Enter a release number-for example, 15.9(3)M2 or 17.3.3. 3. Click Check . Exploitation and Public Announcements o The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory. Source o This vulnerability was found during internal security testing by X.B. of the Cisco Advanced Security Initiatives Group (ASIG). Cisco Security Vulnerability Policy o To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy . This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco. Subscribe to Cisco Security Notifications o Subscribe Related to This Advisory o Cisco Event Response: March 2023 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication URL o https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftdios-dhcpv6-cli-Zf3zTv Revision History o +----------+---------------------------+----------+--------+--------------+ | Version | Description | Section | Status | Date | +----------+---------------------------+----------+--------+--------------+ | 1.0 | Initial public release. | - | Final | 2023-MAR-22 | +----------+---------------------------+----------+--------+--------------+ Legal Disclaimer o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. 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As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: https://auscert.org.au/gpg-key/ iQIVAwUBZBu2vMkNZI30y1K9AQiqPw/+NLKSr+plfaBDOYTYnCVPZ3Ehdz3L58qY nH0L9taOuXqk0YOMriVRMvjrkRG5khMKluNm6ZpS4oDO0pj4tCaGJtXj3hkNjTho StwApCfTOG8EBkLtI6AU6yeerqDoMWemcZ620Yd5stYfohISS5vSuDJUQmCzJ9oR vczwLYA65ZWGLckACi+H07zBX3eEzKP+zo/Kv0CCh0rQNzdrTkS5wZlcDcLj1bar nr2upKoyq6QNOUp0+k+zo+eBKoSSMitxpGUqFdGUDvNhGFEmNAri0BFpCiS/GcYC 17jQT90D6fzk7chX7xeHN72nZzWcG2ckLfofCvQ3PfUlHo+/jCxWifMSJeVeaFAP ZQUcstJKfs2hyHC7+m7j1ROsTprY/sax+3MCT2y3KP01+Bs3jRCUjDPWDpG6+etV mojI5j+FBYHOK/4L79zOVXuoNzYMhgGK2z1sFteGLqLjhCxSjczxNmagpQVRzZOJ Sx5yEGFayqjN9Lgr0kuzP3xhKpAdUXwdKUSM9ZkuHuk/tLrVg9irIqO7RA3Mq9Cu MBUDIUEHsVvjGpz4A2a8vyCJ3IaoMGWPDPszcOO1Eu8EeZsKn9A8FDR4hNhz9UGA OpF4xUlUAV67xvB6flGSx6ch/W7koeMo7vH+FXS13XMMZcHq9Qlsnl5q/OuCyc8H 9Swl7/lILs4= =orrk -----END PGP SIGNATURE-----