Cisco Adaptive Security Appliance and Firepower Threat Defense Software Remote Access VPN Denial of Service Vulnerability – Source:sec.cloudapps.cisco.com

High

Summary

• A vulnerability in the Remote Access VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition on an affected device.

  This vulnerability is due to improper validation of client key data after the TLS session is established. An attacker could exploit this vulnerability by sending a crafted key value to an affected system over the secure TLS session. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

  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-asa-vpn-cZf8gT

  This advisory is part of the October 2024 release of the Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: October 2024 Semiannual Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• This vulnerability affects Cisco ASA Software and FTD Software if they have the Remote Access VPN feature enabled.

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Determine the Cisco ASA Software Configuration

  To determine whether Cisco ASA Software has a vulnerable feature enabled, use the show running-config CLI command. In the following table, the left column lists the Cisco ASA Software features that are vulnerable. The right column indicates the basic configuration for each feature from the show running-config CLI command. If a device is running a vulnerable release and has one of these features enabled, it is affected by this vulnerability.

  Cisco ASA Feature	Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)	crypto ikev2 enable […] client-services port
  AnyConnect SSL VPN	webvpn enable
  Clientless SSL VPN	webvpn enable

  Determine the Cisco FTD Software Configuration

  To determine whether Cisco FTD Software has a vulnerable feature enabled, use the show running-config CLI command. In the following table, the left column lists the Cisco FTD Software features that are vulnerable. The right column indicates the basic configuration for each feature from the show running-config CLI command. If a device is running a vulnerable release and has one of these features enabled, it is affected by this vulnerability.

  Cisco FTD Feature	Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)1	crypto ikev2 enable […] client-services port
  AnyConnect SSL VPN1	webvpn enable

  1. To enable Remote Access VPN features in Cisco Secure Firewall Management Center (FMC) Software, formerly Firepower Management Center Software, choose Devices > VPN > Remote Access. To enable Remote Access VPN features in Cisco Firepower Device Manager (FDM), choose Remote Access VPN.

  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 FMC Software.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco has released free software updates that address the vulnerability described in this advisory. Customers with service contracts that entitle them to regular software updates should obtain security fixes through their usual update channels.

  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.

  The Cisco Support and Downloads page on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool.

  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.

  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.

  Note: For Cisco 3000 Series Industrial Security Appliances (ISAs) that are running Cisco ASA Software, Cisco ASA Software Release 9.16.4.67 has been deferred and replaced by Release 9.16.4.70.

  For instructions on upgrading a Cisco FTD device, see the appropriate Cisco FMC upgrade guide.

  Additional Resources

  For help determining the best Cisco ASA, FMC, or FTD 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

Exploitation and Public Announcements

• 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

• This vulnerability was found during internal security testing by Jason Crowder of the Cisco Advanced Security Initiatives Group (ASIG).

Cisco Security Vulnerability Policy

• 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.

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Related to This Advisory

• Cisco Event Response: October 2024 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-vpn-cZf8gT

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	–	Final	2024-OCT-23

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