Summary

• Multiple Cisco products are affected by a vulnerability in Snort access control policies that could allow an unauthenticated, remote attacker to bypass the configured policies on an affected system.

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

  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-ftd-snort3acp-bypass-3bdR2BEh

  This advisory is part of the November 2023 release of the Cisco ASA, FTD, and FMC Security Advisory Bundled publication. For a complete list of the advisories and links to them, see Cisco Event Response: November 2023 Semiannual Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  For information about which products were affected by this vulnerability at the time of publication, see the sections below.

  Open Source Snort 3

  At the time of publication, this vulnerability affected Open Source Snort 3.

  For information about which Snort releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. For more information on Snort, see the Snort website.

  Cisco FirePOWER and Firepower Threat Defense Software

  At the time of publication, this vulnerability affected Cisco Firepower Threat Defense (FTD) and Cisco FirePOWER Services if they were running Snort 3.

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

  Determine the Cisco FTD Software Snort Configuration

  On new installations of Cisco FTD Software releases 7.0.0 and later, Snort 3 is running by default. On devices that were running Cisco FTD Software Release 6.7.0 or earlier and were upgraded to Release 7.0.0 or later, Snort 2 is running by default.

  To determine if Snort 3 is running on Cisco FTD Software, see Determine the Active Snort Version that Runs on Firepower Threat Defense (FTD). Snort 3 must be active for this vulnerability to be exploitable.

  Cisco IOS XE Products

  At the time of publication, this vulnerability affected the following Cisco products if they were running a vulnerable release of Cisco Unified Threat Defense (UTD) Snort Intrusion Prevention System (IPS) Engine for Cisco IOS XE Software or Cisco UTD Engine for Cisco IOS XE SD-WAN Software.

  Note: UTD is not installed on these devices by default. If the UTD file is not installed, the device is not vulnerable.

  • 1000 Series Integrated Services Routers (ISRs)
  • 4000 Series ISRs
  • Catalyst 8000V Edge Software
  • Catalyst 8200 Series Edge Platforms
  • Catalyst 8300 Series Edge Platforms
  • Catalyst 8500L Edge Platforms
  • Cloud Services Routers 1000V
  • Integrated Services Virtual Router (ISRv)

  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 Whether UTD Is Enabled

  To determine whether UTD is enabled on a device, use the show utd engine standard status command. If the output shows a Yes under Running, UTD is enabled. If there is no output, the device is not affected. The following example shows the output on a device that has UTD enabled:

  Router# show utd engine standard status 
  Engine version       : 1.0.19_SV2.9.16.1_XE17.3
  Profile              : Cloud-Low
  System memory        :
               Usage  : 6.00 %
               Status : Green
  Number of engines    : 1

  
  

  Engine        Running    Health     Reason    
  ===========================================
  Engine(#1):   Yes        Green      None
  =======================================================
  
  .
  .
  .

  
  

  Cisco Umbrella Secure Internet Gateway

  This vulnerability affects Cisco Umbrella Secure Internet Gateway (SIG), which is cloud based.

  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 Open Source Snort 2.

  Cisco also has confirmed that this vulnerability does not affect the following Cisco products:

  • Adaptive Security Appliance (ASA) Software
  • Cyber Vision
  • Firepower Management Center (FMC) Software
  • Meraki Appliances

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• At the time of publication, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  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.

  Fixed Releases

  For information about fixed releases, see the sections below.

  Open Source Snort Software

  At the time of publication, the release information in the following table was accurate.

  Snort Release	First Fixed Release
  2.x	Not vulnerable
  3.x	3.1.57.0

  
  

  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.

  Only this advisory All Critical and High advisories All advisories Cisco ASA Software Cisco FMC Software Cisco FTD Software Any Platform 3000 Series Industrial Security Appliances (ISA) ASA 5500-X Series Firewalls ASA Service Module Adaptive Security Virtual Appliance (ASAv) Firepower 1000 Series Firepower 2100 Series Firepower 4100 Series Firepower 9000 Series Secure Firewall 3100 Series

  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 UTD Software

  At the time of publication, the release information in the following table was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  Cisco IOS XE Software Release	First Fixed Release
  Earlier than 17.12	Not vulnerable
  17.12	17.12.2 (Nov 2023)
  17.13	17.13.1 (Dec 2023)

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

  Cisco Umbrella Secure Internet Gateway (SIG)

  Cisco has addressed this vulnerability in Cisco Umbrella SIG, which is cloud based. No user action is required.

  Customers who need additional information are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

Exploitation and Public Announcements

• The Cisco 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 the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort3acp-bypass-3bdR2BEh

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated fixed software information.	Fixed Releases	Final	2024-FEB-06
  1.0	Initial public release.	-	Final	2023-NOV-01

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