Cisco Security Advisory
Cisco Adaptive Security Appliance and Firepower Threat Defense Software AnyConnect Access Control List Bypass Vulnerabilities
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
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Multiple vulnerabilities in the AnyConnect firewall for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass a configured access control list (ACL) and allow traffic that should have been denied to flow through an affected device.
These vulnerabilities are due to a logic error in populating group ACLs when an AnyConnect client establishes a new session toward an affected device. An attacker could exploit these vulnerabilities by establishing an AnyConnect connection to the affected device. A successful exploit could allow the attacker to bypass configured ACL rules.
Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-acl-bypass-VvnLNKqfThis 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.
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Vulnerable Products
At the time of publication, these vulnerabilities affected Cisco devices if they were running a vulnerable release of Cisco ASA or FTD Software and had the Forward Reference and AnyConnect Firewall Rule features enabled.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine the Device Configuration
To determine whether the Forward Reference and AnyConnect Firewall Rule features are enabled on a device, use the show running-config CLI command.
For devices that are running a release earlier than Cisco ASA Software Release 9.18.1 or Cisco FTD Software Release 7.2.0, examine the output for forward-reference enable and anyconnect firewall-rule client-interface. If both commands are present, the device is affected by these vulnerabilities.
For devices running Cisco ASA Software Release 9.18.1 or later or Cisco FTD Software Release 7.2.0 or later, Forward Reference is enabled by default and cannot be disabled. Examine the output of the show running-config CLI command for anyconnect firewall-rule client-interface. If the command is present, determine if an object group is configured for the command as the destination network, the destination port, or both:
- With an object group as destination network, only the resulting ACL pushed to the client will include a permit rule to any destination network (0.0.0.0/0).
- With an object group as destination port, only the resulting ACL pushed to the client will include a permit rule to any destination port (1-65535).
- With an object group as both destination network and destination port, the resulting ACL pushed to the client will include a permit rule to any destination network (0.0.0.0/0) on any destination port (1-65535).
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect Cisco Secure Firewall Management Center (FMC) Software, formerly Firepower Management Center Software.
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There are no workarounds that address these vulnerabilities.
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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:
- Choose which advisories the tool will search-all advisories, only advisories with a Critical or High Security Impact Rating (SIR), or only this advisory.
- Choose the appropriate software.
- Choose the appropriate platform.
- Enter a release number-for example, 9.16.2.11 for Cisco ASA Software or 6.6.7 for Cisco FTD Software.
- 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.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
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These vulnerabilities were found during the resolution of a Cisco TAC support case.
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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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Version Description Section Status Date 1.1 Removed hyphen in the CLI command. Vulnerable Products Final 2024-OCT-24 1.0 Initial public release. - Final 2024-OCT-23
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