Summary

• A vulnerability in the Secure Sockets Layer (SSL)/Transport Layer Security (TLS) handler of Cisco Firepower Threat Defense (FTD) Software when running on the Cisco Firepower 1000 Series platform could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device.

  The vulnerability is due to a communication error between internal functions. An attacker could exploit this vulnerability by sending a crafted SSL/TLS message to an affected device. A successful exploit could allow the attacker to cause a buffer underrun, which leads to a crash. The crash causes the affected device to reload.

  Cisco has released software updates that address the vulnerability described in this advisory. 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-tls-dos-4v5nmWtZ

  This advisory is part of the May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication, which includes 12 Cisco Security Advisories that describe 12 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Firepower 1000 Series appliances if they are running a vulnerable release of Cisco FTD Software and have a feature enabled that causes the device to process SSL/TLS messages. These features include, but are not limited to, the following:

  • AnyConnect SSL VPN
  • Clientless SSL VPN

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

  Determine Whether a Device Could Process SSL or TLS Messages

  To verify whether a device that is running Cisco FTD Software could process SSL or TLS packets, use the show asp table socket | include SSL|DTLS command and verify that it returns output. When this command returns any output, the device is vulnerable. When this command returns empty output, the device is not affected by the vulnerability described in this advisory. The following example shows the output of the show asp table socket | include SSL|DTLS command from a device that is vulnerable:

  ftd# show asp table socket | include SSL|DTLS
  SSL       0005aa68  LISTEN     x.x.x.x:443      0.0.0.0:*   
  SSL       002d9e38  LISTEN     x.x.x.x:8443     0.0.0.0:*
  DTLS      0018f7a8  LISTEN     10.0.0.250:443   0.0.0.0:*  

  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 Cisco products:

  • Adaptive Security Appliance (ASA) Software
  • Firepower Management Center (FMC) Software
  • FTD Software running on any platform other than the Cisco Firepower 1000 Series

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 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.

  When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts 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.

  Fixed Releases

  In the following table(s), the left column lists Cisco software releases. The center column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability. The right column indicates whether a release is affected by any of the vulnerabilities described in this bundle and which release includes fixes for those vulnerabilities.

  Cisco FTD Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories
  Earlier than 6.1.01	Not applicable2	Not applicable2
  6.1.0	Not applicable2	Not applicable2
  6.2.0	Not applicable2	Not applicable2
  6.2.1	Not applicable2	Not applicable2
  6.2.2	Not applicable2	Not applicable2
  6.2.3	Not applicable2	Not applicable2
  6.3.0	Not applicable2	Not applicable2
  6.4.0	6.4.0.9	6.4.0.9
  6.5.0	Not vulnerable	6.5.0.5 (future release) Cisco_FTD_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_FP1K_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_FP2K_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_Hotfix_H-6.5.0.5-2.sh.REL.tar and later
  6.6.0	Not vulnerable	Not vulnerable

  1. Cisco FMC and FTD Software releases 6.0.1 and earlier have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.
  2. Only Cisco FTD Software releases 6.4.0 and later support the Cisco Firepower 1000 Series.

  To upgrade to a fixed release of Cisco FTD Software, customers can do one of the following:

  • For devices that are managed by using Cisco Firepower Management Center (FMC), use the FMC interface to install the upgrade. After installation is complete, reapply the access control policy.
  • For devices that are managed by using Cisco Firepower Device Manager (FDM), use the FDM interface to install the upgrade. After installation is complete, reapply the access control policy.

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 by Ilkin Gasimov of Cisco during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-tls-dos-4v5nmWtZ

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated Hot Fixes for FTD releases 6.4.0 and 6.5.0.	Fixed Releases	Final	2020-MAY-15
  1.0	Initial public release.	-	Final	2020-MAY-06
  1.2	Updated fixed release information for FTD Release 6.4.0.	Fixed Releases	Final	2020-MAY-06

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