Summary

• A vulnerability in the Flexible NetFlow Version 9 packet processor of Cisco IOS XE Software for Cisco Catalyst 9800 Series Wireless Controllers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

  The vulnerability is due to improper validation of parameters in a Flexible NetFlow Version 9 record. An attacker could exploit this vulnerability by sending a malformed Flexible NetFlow Version 9 packet to the Control and Provisioning of Wireless Access Points (CAPWAP) data port of an affected device. An exploit could allow the attacker to trigger an infinite loop, resulting in a process crash that would cause a reload of the device.

  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-iosxe-fnfv9-dos-HND6Fc9u

  This advisory is part of the June 3, 2020, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 23 Cisco Security Advisories that describe 25 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: June 2020 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Catalyst 9800 Series Wireless Controllers that are running a vulnerable release of Cisco IOS XE Software and have the Application Visibility and Control (AVC) feature enabled.

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

  Determine Whether AVC Is Configured

  To determine whether the AVC feature is configured, administrators can use one of the following options:

  Option 1: GUI

  Log in to the web-based management interface, navigate to Configuration > Services > Application Visibility, and check for any enabled profiles. If any profile is enabled, the AVC feature is configured.

  Option 2: CLI

  Administrators can also use the show running-config | section flow|wireless profile command on the CLI and look for whether all of the following are configured:

  1. A flow monitor
  2. An active WLAN policy profile invoking such flow monitor

  The following example shows the output of the show running-config | section flow|wireless profile command on a device that has flow monitor fm configured and on which the active WLAN policy profile default-policy-profile invokes flow monitor fm for ingress ("input") traffic:

  ios-xe#show running-config | section flow|wireless profile
  flow monitor fm
   record rec
  .
  .
  .
  wireless profile policy default-policy-profile
  .
  .
  .
   ipv4 flow monitor fm input
  .
  .
  .
   no shutdown

  Note: The device would also be vulnerable if the flow monitor were invoked for egress ("output") traffic only or for both ingress and egress traffic.

  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:

  • Catalyst 9800 Embedded Wireless Controller Software for Cisco Catalyst 9300 or 9500 Series Switches
  • IOS Software
  • IOS XR Software
  • NX-OS Software
  • Wireless LAN Controller (WLC) Software

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.

  Cisco IOS and IOS XE Software

  To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides the Cisco Software Checker to identify any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified (“Combined First Fixed”).

  Customers can use the Cisco Software Checker to search advisories in the following ways:

  • Choose the software and one or more releases
  • Upload a .txt file that includes a list of specific releases
  • Enter the output of the show version command

  After initiating a search, customers can customize the search to include all Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication.

  Customers can also use the following form to determine whether a release is affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE Software release—for example, 15.1(4)M2 or 3.13.8S:

  By default, the Cisco Software Checker includes results only for vulnerabilities that have a Critical or High Security Impact Rating (SIR). To include results for Medium SIR vulnerabilities, customers can use the Cisco Software Checker on Cisco.com and check the Medium check box in the drop-down list under Impact Rating when customizing a search.

  For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the Cisco IOS XE Software release.

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 Mathieu Monney of Cisco during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-fnfv9-dos-HND6Fc9u

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2020-JUN-03

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