Summary

• Update from October 22nd, 2020: Cisco has become aware of a new Cisco Adaptive Security Appliance vulnerability that could affect the fixed releases recommended for code trains 9.13 and 9.14 in the Fixed Software section of this advisory. See the Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability for additional information.

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  A vulnerability in the FTP inspection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass FTP inspection.

  The vulnerability is due to ineffective flow tracking of FTP traffic. An attacker could exploit this vulnerability by sending crafted FTP traffic through an affected device. A successful exploit could allow the attacker to bypass FTP inspection and successfully complete FTP connections.

  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-ftpbypass-HY3UTxYu

Affected Products

• Vulnerable Products

  At the time of publication, this vulnerability affected devices if they were running a vulnerable release of Cisco ASA Software or FTD Software and had strict FTP inspection enabled.

  For information about which Cisco software releases were vulnerable, 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 FTP Inspection Is Enabled on an ASA

  To determine whether FTP inspection is enabled on an ASA, use the show running-config policy-map command and then the show running-config service-policy command.

  Use the show running-config policy-map command and check whether the inspect ftp strict command is present in at least one policy map. In the following output, the global-policy policy map includes the inspect ftp strict command:

  asa# show running-config policy-map 
  !
  policy-map global_policy
   class inspection_default
    inspect ip-options 
    inspect netbios 
    inspect rtsp 
    inspect sunrpc 
    inspect tftp 
    inspect xdmcp 
    inspect dns preset_dns_map 
    inspect ftp strict 
    inspect h323 h225

  Use the show running-config service-policy command and check whether the policy map is applied, either globally or to a single interface. The following output shows the global-policy policy map applied globally:

  asa# show running-config service-policy
  service-policy global_policy global

  If the policy map that contains the inspect ftp strict command is applied globally or to an interface, strict FTP inspection is enabled.

  Determine Whether FTP Inspection Is Enabled on FTD

  Configuring inspect ftp strict on FTD requires the use of FlexConfig. To determine if inspect ftp strict is enabled on an FTD device, Secure Shell (SSH) to the management interface of the device and use the process previously outlined for the ASA.

  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 Cisco Firepower Management Center (FMC) Software.

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.

  Fixed Releases

  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.

  The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability described in this advisory and which release included the fix for this vulnerability.

  Cisco ASA Software

  Cisco ASA Software Release	First Fixed Release for This Vulnerability
  Earlier than 9.61	Migrate to a fixed release.
  9.61	Migrate to a fixed release.
  9.71	Migrate to a fixed release.
  9.8	9.8.4.26
  9.9	9.9.2.80
  9.10	9.10.1.44
  9.12	9.12.4.2
  9.13	9.13.1.13
  9.14	9.14.1.19

  1. Cisco ASA Software releases 9.7 and earlier have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.

  Cisco FTD Software

  Cisco FTD Software Release	First Fixed Release for This Vulnerability
  Earlier than 6.2.21	Migrate to a fixed release.
  6.2.2	Migrate to a fixed release.
  6.2.3	Migrate to a fixed release.
  6.3.0	6.3.0.6 (future release)
  6.4.0	6.4.0.10
  6.5.0	6.5.0.5 (future release)
  6.6.0	6.6.1

  1. Cisco FMC and FTD Software releases 6.0.1 and earlier, as well as releases 6.2.0 and 6.2.1, have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.

  To upgrade to a fixed release of Cisco FTD Software, 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 during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ftpbypass-HY3UTxYu

Revision History

• Version	Description	Section	Status	Date
  2.0	Updated the Summary section to provide information on a new vulnerability affecting fixed release recommendations for code trains 9.13 and 9.14.	Summary	Final	2020-OCT-22
  1.0	Initial public release.	—	Final	2020-OCT-21

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