Summary

• A vulnerability in the interaction of SIP and Snort 3 for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 3 detection engine to restart.

  This vulnerability is due to a lack of error-checking when SIP bidirectional flows are being inspected by Snort 3. An attacker could exploit this vulnerability by sending a stream of crafted SIP traffic through an interface on the targeted device. A successful exploit could allow the attacker to trigger a restart of the Snort 3 process, resulting in a denial of service (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-ftdsnort3sip-dos-A4cHeArC

  This advisory is part of the November 2022 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 2022 Semiannual Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  At the time of publication, this vulnerability affected Cisco FTD Software if it was running Release 7.2.0 or 7.2.0.1 and had the Snort 3 detection engine configured with an SIP inspection policy.

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

  Determine Cisco FTD Software 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.

  Determine Cisco FTD Software Configuration Using the FTD Software CLI

  To determine whether Snort 3 is configured on a device that is running Cisco FTD Software, log in to the Cisco FTD Software CLI and use the show snort3 status command. If the command produces the following output, the device is running Snort 3 and is affected by this vulnerability:

  show snort3 status
  Currently running Snort 3

  Determine Cisco FTD Software Configuration for Cisco Firepower Management Center Software-Managed Devices

  To determine whether Snort 3 is configured on a device that is managed by Cisco Firepower Management Center (FMC) Software, complete the following steps:

  1. Log in to the Cisco FMC Software web interface.
  2. From the Devices menu, choose Device Management.
  3. Choose the appropriate Cisco FTD device.
  4. Click the Edit pencil icon.
  5. Choose the Device tab and look in the Inspection Engine area.
  • If Snort 2 is listed, the device is not affected by this vulnerability.
  • If Snort 3 is listed, the device is affected by this vulnerability.

  Determine Cisco FTD Software Configuration for Cisco Firepower Device Manager Software-Managed Devices

  To determine whether Snort 3 is configured on a device that is managed by Cisco Firepower Device Manager (FDM) Software, complete the following steps:

  1. Log in to the Cisco FTD Software web interface.
  2. From the main menu, choose Policies.
  3. Choose the Intrusion tab.
  4. Look for the Inspection Engine version. The version will start with either a 2 for Snort 2 or a 3 for Snort 3.
  • If the device is running a Snort 2 version, it is not affected by this vulnerability.
  • If the device is running a Snort 3 version, it is affected by this vulnerability.

  Determine Cisco FTD Software Configuration for Cisco Defense Orchestrator-Managed Devices

  To determine whether Snort 3 is configured on a device that is managed by Cisco Defense Orchestrator, complete the following steps:

  1. Log in to the Cisco Defense Orchestrator web interface.
  2. From the Inventory menu, choose the appropriate Cisco FTD device.
  3. In the Device Details area, look for Snort Version. The version will start with either a 2 for Snort 2 or a 3 for Snort 3.
  • If the device is running a Snort 2 version, it is not affected by this vulnerability.
  • If the device is running a Snort 3 version, it is affected by this vulnerability.

  Determine Cisco FTD Software SIP Configuration

  To determine whether SIP inspection is configured on Cisco FTD Software, run the show service-policy | include sip command in the CLI. The device is considered vulnerable if Snort 3 is configured as described above and if the output includes Inspect: sip, as shown in the following example:

  device# show service-policy | include sip
  Inspect: sip , packet 2, lock fail 0, drop 0, reset-drop 0, 5-min-pkt-rate 0 pkts/sec, v6-fail-close 0 sctp-drop-override 0 

  Note: SIP inspection is enabled by default on Cisco FTD Software. For detailed information about the default settings for application inspection policies, see the Cisco ASA Series Firewall CLI Configuration Guide.

  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 the following products:

  • Cisco Adaptive Security Appliance (ASA) Software
  • Cisco Firepower Management Center (FMC) Software
  • Open Source Snort 2
  • Open Source Snort 3

Details

• The following Cisco FTD Software Snort 3 configuration parameters govern how traffic is handled if the Snort 3 process restarts, which could change how SIP traffic is handled during an exploit of this vulnerability.

  • Snort Fail Open
  • snort preserve-connection

  For additional information, see the Firepower Management Center Configuration Guide.

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.

  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

  
  

  For instructions on upgrading your FTD device, see Cisco Firepower Management Center Upgrade Guide.

  
  

  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

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 the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftdsnort3sip-dos-A4cHeArC

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2022-NOV-09

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