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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.3659.2 Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability 28 October 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco Adaptive Security Appliance Software Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2020-27124 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ssl-dos-7uZWwSEy Revision History: October 28 2020: vendor issued minor update October 23 2020: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability Priority: High Advisory ID: cisco-sa-asa-ssl-dos-7uZWwSEy First Published: 2020 October 22 16:00 GMT Last Updated: 2020 October 27 20:31 GMT Version 1.1: Final Workarounds: No workarounds availableCisco Bug IDs: CSCvt64822 CVE-2020-27124 CWE-457 Summary o A vulnerability in the SSL/TLS handler of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause the affected device to reload unexpectedly, leading to a denial of service (DoS) condition. The vulnerability is due to improper error handling on established SSL/TLS connections. An attacker could exploit this vulnerability by establishing an SSL/TLS connection with the affected device and then sending a malicious SSL/TLS message within that connection. A successful exploit could allow the attacker to cause the device to reload. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-asa-ssl-dos-7uZWwSEy Affected Products o Vulnerable Products This vulnerability affects Cisco ASA Software releases 9.13.1.12, 9.13.1.13, and 9.14.1.10 if they have a feature enabled that causes the device to process SSL/TLS messages. These features include, but are not limited to, the following: AnyConnect SSL VPN ^ 1 Clientless SSL VPN ^ 1 HTTP server used for the management interface 1. Cisco Adaptive Security Virtual Appliances (ASAv) are not vulnerable for these configurations. For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory. Determine Whether a Device Could Process SSL or TLS Messages To verify whether a device that is running Cisco ASA Software could process SSL or TLS packets, use the show asp table socket | include SSL|DTLS command and verify that it returns output. When this command returns any output, the device is vulnerable. When this command returns empty output, the device is not affected by the vulnerability described in this advisory. The following example shows the output of the show asp table socket | include SSL|DTLS command from a device that is vulnerable: ftd# show asp table socket | include SSL|DTLS SSL 0005aa68 LISTEN x.x.x.x:443 0.0.0.0:* SSL 002d9e38 LISTEN x.x.x.x:8443 0.0.0.0:* DTLS 0018f7a8 LISTEN 10.0.0.250:443 0.0.0.0:* 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 Cisco Firepower Management Center (FMC) Software or Cisco Firepower Threat Defense (FTD) Software. Workarounds o There are no workarounds that address this vulnerability. Fixed Software o Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license: https://www.cisco.com/c/en/us/products/end-user-license-agreement.html Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades. 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. Customers Without Service Contracts Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c /en/us/support/web/tsd-cisco-worldwide-contacts.html Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Fixed Releases Cisco has fixed this vulnerability in Cisco ASA Software Release 9.13.1.16 and releases 9.14.1.15 and later. 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 the resolution of a Cisco TAC support case. 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. URL o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-asa-ssl-dos-7uZWwSEy Revision History o +---------+----------------------------+----------+---------+-------------+ | Version | Description | Section | Status | Date | +---------+----------------------------+----------+---------+-------------+ | | In the Fixed Releases | | | | | 1.1 | section, indicated that | Fixed | Final | 2020-OCT-27 | | | Release 9.13.1.16 is now | Releases | | | | | available. | | | | +---------+----------------------------+----------+---------+-------------+ | 1.0 | Initial public release. | - | Interim | 2020-OCT-22 | +---------+----------------------------+----------+---------+-------------+ - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. 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). 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