Cisco Adaptive Security Appliance and Firepower Threat Defense Software NSG Access Control List Bypass Vulnerability – Source:sec.cloudapps.cisco.com

Medium

Summary

• A vulnerability in the Network Service Group (NSG) feature of 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 be denied to flow through an affected device.

  This vulnerability is due to a logic error that occurs when NSG ACLs are populated on an affected device. An attacker could exploit this vulnerability by establishing a connection to the affected device. A successful exploit could allow the attacker to bypass configured ACL rules.

  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-asaftd-nsgacl-bypass-77XnEAsL

  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

• At the time of publication, this vulnerability affected Cisco products if they were running a vulnerable release of Cisco ASA Software or FTD Software and had NSG ACL enabled.

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

  Determine the NSG ACL Configuration

  To determine the NSG ACL optimization configuration, use the show access-list | inc object-group-network-service command on the device CLI. The following example shows the output of the command on a device that has the NSG ACL optimization feature enabled and may be affected by this vulnerability:

  # show access-list | inc object-group-network-service
  object-group-network-service

  If the command returns empty output or an output of no object-group-network-service, the NSG ACL feature is disabled and the device is not affected by this vulnerability.

  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 Secure Firewall Management Center (FMC) Software, formerly Firepower Management Center Software.

Details

• Exploitation of this vulnerability could allow an attacker to bypass protections that are provided by an ACL that is applied on an affected device. The overall impact of exploitation depends on the importance of the assets that the ACL was supposed to protect. Customers should evaluate how exploitation of this vulnerability would impact their network and proceed according to their own vulnerability-handling and remediation processes.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• 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.

  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.

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-asaftd-nsgacl-bypass-77XnEAsL

Revision History

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

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