Summary

• A vulnerability in the FTP inspection engine of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition.

  The vulnerability exists because the affected software fails to release spinlocks when a device is running low on system memory, if the software is configured to apply FTP inspection and an access control rule to transit traffic, and the access control rule is associated with an FTP file policy. An attacker could exploit this vulnerability by sending a high rate of transit traffic through an affected device to cause a low-memory condition on the device. A successful exploit could allow the attacker to cause a software panic on the affected device, which could cause the device to reload and result in a temporary 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-20181003-ftd-inspect-dos

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Firepower Threat Defense (FTD) Software Releases 6.2.3.x prior to Release 6.2.3.4, if FTP inspection is enabled, an access control rule with an associated FTP file policy is also enabled, and the software is running on any of the following Cisco products:

  • 3000 Series Industrial Security Appliances (ISAs)
  • ASA 5500-X Series Next-Generation Firewalls
  • Firepower 2100 Series Security Appliances
  • Firepower 4100 Series Security Appliances
  • Firepower 9300 ASA Security Module
  • Firepower Threat Defense Virtual (FTDv)

  FTP inspection is enabled by default in Cisco FTD Software. For detailed information about the default settings for application inspection policies, refer to the Cisco ASA Series Firewall CLI Configuration Guide.

  Determine the Cisco FTD Software Release

  To determine which Cisco FTD Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and refer to the output of the command. The following example shows the output of the command for a device that is running Cisco FTD Software Release 6.2.0:

  > show version
  
  ---------------------[ ftd ]---------------------
  Model : Cisco ASA5525-X Threat Defense (75) Version 6.2.0 (Build 362)
  UUID : 2849ba3c-ecb8-11e6-98ca-b9fc2975893c
  Rules update version : 2017-03-15-001-vrt
  VDB version : 279
  ----------------------------------------------------

  Determine Whether FTP File Policies Are Associated with a Rule

  To determine whether FTP file policies are associated with access control rules that are enabled for a device, administrators can do either of the following:

  • For devices that are managed by using Cisco Firepower Management Center (FMC), open Cisco FMC, choose Policies > Access Control > Malware & File, and then choose an access control rule. Click the File Policy tab to view detailed information about any file policies that are associated with the rule.
  • For devices that are managed by using Cisco Firepower Device Manager (FDM), open Cisco FDM, choose Policies > Access Control, and then choose an access control rule. Click the File Policy tab to view detailed information about any file policies that are associated with the rule. Note that Cisco FDM supports use of predefined file policies only. Administrators cannot create file policies for access control rules.

  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 Adaptive Security Appliance (ASA) Software.

Workarounds

• There are no workarounds that address this vulnerability. However, administrators can disable FTP inspection. To disable FTP inspection in Cisco FTD Software Releases 6.2 and later, use Cisco FMC to add the following FlexConfig policy:

  policy-map global_policy
   class inspection_default
    no inspect ftp

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

  Customers are advised to upgrade to an appropriate release as indicated in the applicable table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:

  • cisco-sa-20181003-asa-dma-dos: Cisco Adaptive Security Appliance Direct Memory Access Denial of Service Vulnerability
  • cisco-sa-20181003-ftd-inspect-dos: Cisco Firepower Threat Defense Software FTP Inspection Denial of Service Vulnerability

  In the following table(s), the left column lists releases of Cisco software. 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 all the vulnerabilities described in this collection of advisories 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 Collection of Advisories
  6.0	Not vulnerable	Migrate to 6.1.0.7
  6.0.1	Not vulnerable	Migrate to 6.1.0.7
  6.1.0	Not vulnerable	6.1.0.7
  6.2.0	Not vulnerable	6.2.0.7 (future release)
  6.2.1	Not vulnerable	Migrate to 6.2.2.5 (future release)
  6.2.2	Not vulnerable	6.2.2.5 (future release)
  6.2.3	6.2.3.4 6.2.3-851 6.2.3-9912	6.2.3.4 6.2.3-851 6.2.3-9912

  ¹ The software image for Cisco Firepower Threat Defense Virtual (FTDv) for the AWS Cloud.
  ² The software image for Cisco FTDv for the Microsoft Azure Cloud.

  To upgrade to a fixed release of Cisco Firepower System 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 and, after installation is complete, reapply the access control policy. The Snort version that is installed depends on the FMC release.
  • For devices that are managed by using Cisco Adaptive Security Device Manager (ASDM) or Cisco Firepower Device Manager (FDM), use the ASDM or FDM interface to install the upgrade and, 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-20181003-ftd-inspect-dos

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2018-October-03

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