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 IP fragment-handling implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a memory leak on an affected device. This memory leak could prevent traffic from being processed through the device, resulting in a denial of service (DoS) condition. 

  The vulnerability is due to improper error handling when specific failures occur during IP fragment reassembly. An attacker could exploit this vulnerability by sending crafted, fragmented IP traffic to a targeted device. A successful exploit could allow the attacker to continuously consume memory on the affected device and eventually impact traffic, resulting in a DoS condition. The device could require a manual reboot to recover from the DoS condition.

  Note: This vulnerability applies to both IP Version 4 (IPv4) and IP Version 6 (IPv6) traffic.

  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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-frag-memleak-mCtqdP9n

  This advisory is part of the October 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication, which includes 17 Cisco Security Advisories that describe 17 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: October 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco products if they are running Cisco FTD Software Release 6.6.0.1 or one of the following Cisco ASA Software releases:

  • 9.8.4.22
  • 9.8.4.25
  • 9.12.4.2
  • 9.12.4.3
  • 9.13.1.12
  • 9.14.1.15

  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.

Indicators of Compromise

• A device may have been compromised by this vulnerability if the show blocks command indicates a leak of larger-size memory blocks (2,048 or above). If there is a memory leak, the device could stop passing traffic or performance could degrade. In the following example, the memory blocks of size 9344 have leaked to the point where there are 0 blocks available:

  # show blocks
    SIZE    MAX    LOW    CNT
       0   1450   1448   1450
       4    100     99     99
      80   1000    950    984
     256   4148   3898   4040
    1550   6279   6184   6258
    2048    600    598    600
    2560    164    164    164
    4096    100    100    100
    8192    100    100    100
    9344    60000    0      0
   16384    102    102    102
   65536     16     16     16

  Contact the Cisco Technical Assistance Center (TAC) if additional assistance is required to determine whether a device has been compromised by exploitation of this vulnerability.

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 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 ASA Software

  Cisco ASA Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories
  Earlier than 9.61	Not vulnerable.	Migrate to a fixed release.
  9.61	Not vulnerable.	9.6.4.45
  9.71	Not vulnerable.	Migrate to a fixed release.
  9.8	9.8.4.26 (only 9.8.4.22 and 9.8.4.25 are vulnerable)	9.8.4.29
  9.9	Not vulnerable	9.9.2.80
  9.10	Not vulnerable	9.10.1.44
  9.12	9.12.4.4 (only 9.12.4.2 and 9.12.4.3 are vulnerable)	9.12.4.4
  9.13	9.13.1.13 (only 9.13.1.12 is vulnerable)	9.13.1.13
  9.14	9.14.1.19 (only 9.14.1.15 is vulnerable)	9.14.1.30

  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	First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories
  Earlier than 6.2.21	Not vulnerable.	Migrate to a fixed release.
  6.2.2	Not vulnerable.	Migrate to a fixed release.
  6.2.3	Not vulnerable.	Migrate to a fixed release.
  6.3.0	Not vulnerable.	Migrate to a fixed release.
  6.4.0	Not vulnerable.	Migrate to a fixed release.
  6.5.0	Not vulnerable.	Migrate to a fixed release.
  6.6.0	6.6.1	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 by Santosh Krishnamurthy of Cisco during internal security testing.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-frag-memleak-mCtqdP9n

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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