Summary

• Multiple vulnerabilities in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to execute arbitrary commands with root privileges.

  For more information about these vulnerabilities, see the Details section of this advisory.

  Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-cmdinject-FmzsLN8

  This advisory is part of the October 2021 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: October 2021 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  These vulnerabilities affect Cisco FTD Software.

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

  Determine the Affected FTD Software Configuration

  In the following table, the left column indicates the Cisco FTD Software configuration and the right column indicates the associated Cisco CVE IDs that are described in the Details section of this advisory.

  Cisco FTD Configuration	Associated CVE IDs
  Multi-instance1,2	CVE-2021-34755 and CVE-2021-34756
  Default	CVE-2021-34752

  1. The multi-instance configuration is supported as of Cisco FTD Software Release 6.3.0, so earlier releases are not affected by these multi-instance vulnerabilities. 

  2. The only Cisco FTD Software platforms that support multi-instance operation are:

  • Firepower 4100 Series Security Appliances
  • Firepower 9300 Series Security Appliances

  Determine the Device Configuration

  Note: This section applies only to CVE-2021-34755 and CVE-2021-34756, which require multi-instance configuration.

  To determine whether a device is providing multi-instance services, log in to the Cisco FXOS CLI and use the show app-instance command within the ssa scope. If the Deploy Type field has a value of Container, application instances are present and the device is affected by this vulnerability. The following example shows the command output for an affected device:

  firepower# scope ssa
  firepower /ssa # show app-instance
  

  App Name	Identifier	Slot ID	Admin State	Oper State	Running Version	Startup Version	Deploy Type	Turbo Mode	Profile Name	Cluster State	Cluster Role
  -----	-------	------	------	-----	-------	-------	------	-----	-----	-------	-------
  ftd	ftd1	1	Enabled	Online	6.2.3.14	6.2.3.14	Native	No		Not Applicable	None
  ftd	ftd2-1	2	Enabled	Online	6.4.0.4	6.4.0.4	Container	No	mid	Not Applicable	None

   

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products section of this advisory are known to be affected by this these vulnerabilities.

  Cisco has confirmed that these vulnerabilities do not affect Cisco Adaptive Security Appliance (ASA) Software or Cisco Firepower Management Center (FMC) Software.

Details

• The vulnerabilities are not dependent on one another. Exploitation of one of the vulnerabilities is not required to exploit another vulnerability. In addition, a software release that is affected by one of the vulnerabilities may not be affected by the other vulnerabilities.

  Details about the vulnerabilities are as follows:

  CVE-2021-34755 and CVE-2021-34756: Cisco FTD Software Command Injection Vulnerabilities

  Multiple vulnerabilities in the CLI of Cisco FTD Software could allow an authenticated, local attacker to execute arbitrary commands with root privileges on the underlying operating system of an affected device that is running in multi-instance mode.

  These vulnerabilities are due to insufficient validation of user-supplied command arguments. An attacker could exploit these vulnerabilities by submitting crafted input to the affected command. A successful exploit could allow the attacker to execute commands with root privileges on the underlying operating system.

  Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

  Bug ID(s): CSCvx86283, CSCvy16559
  CVE IDs: CVE-2021-34755 and CVE-2021-34756
  Security Impact Rating (SIR): High
  CVSS Base Score: 7.8
  CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

  CVE-2021-34752: Cisco FTD Software Command Injection Vulnerability

  A vulnerability in the CLI of Cisco FTD Software could allow an authenticated, local attacker with administrative privileges to execute arbitrary commands with root privileges on the underlying operating system of an affected device. 

  This vulnerability is due to insufficient validation of user-supplied command arguments. An attacker could exploit this vulnerability by submitting crafted input to the affected commands. A successful exploit could allow the attacker to execute commands with root privileges on the underlying operating system.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Bug ID(s): CSCvy16573, CSCvy19225
  CVE ID: CVE-2021-34752
  Security Impact Rating (SIR): Medium
  CVSS Base Score: 6.7
  CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Workarounds

• There are no workarounds that address these vulnerabilities.

Fixed Software

• Cisco has released free software updates that address the vulnerabilities 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 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.

  FTD Software

  Cisco FTD Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories
  6.2.2 and earlier1	Migrate to a fixed release.	Migrate to a fixed release.
  6.2.3	Migrate to a fixed release.	Migrate to a fixed release.
  6.3.01	Migrate to a fixed release.	Migrate to a fixed release.
  6.4.0	6.4.0.13 (Nov 2021)	6.4.0.13 (Nov 2021)
  6.5.01	Migrate to a fixed release.	Migrate to a fixed release.
  6.6.0	6.6.5	6.6.5.1 (Nov 2021)
  6.7.0	6.7.0.3 (Jan 2022)	6.7.0.3 (Jan 2022)
  7.0.0	7.0.1	7.0.1

  1. Cisco FMC and FTD Software releases 6.2.2 and earlier, as well as releases 6.3.0 and 6.5.0, have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for these vulnerabilities.

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

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

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

• CVE-2021-34755: This vulnerability was found by Ilkin Gasimov of Cisco during internal security testing.

  CVE-2021-34756 and CVE-2021-34752: These vulnerabilities were found by Brandon Sakai of Cisco during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-cmdinject-FmzsLN8

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2021-OCT-27

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