Summary

• A vulnerability in the wireless controller manager of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a restart of the switch and result in a denial of service (DoS) condition.
  
  The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by submitting a crafted association request. An exploit could allow the attacker to cause the switch to restart.
  
  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-20170927-ios-xe

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Catalyst 3650 and 3850 switches running IOS XE Software versions 16.1 through 16.3.3, and acting as wireless LAN controllers (WLC). For information about which Cisco IOS XE Software releases are vulnerable, see the Fixed Software section of this advisory.
  
  To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS XE Software or similar text.
  
  The following example shows the output of the show version command on a device that is running Cisco IOS XE Software Release 3.16.1aS:
  
  

  Router> show version
  
      Cisco IOS XE Software, Version 03.16.01a.S - Extended Support Release
      Cisco IOS Software, ASR1000 Software (PPC_LINUX_IOSD-ADVENTERPRISEK9-M), Version 15.5(3)S1a, RELEASE SOFTWARE (fc1)
      Technical Support: http://www.cisco.com/techsupport
      Copyright (c) 1986-2015 by Cisco Systems, Inc.
      Compiled Wed 04-Nov-15 17:40 by mcpre
      .
      .
      .

  For information about the naming and numbering conventions for Cisco IOS XE Software releases, see White Paper: Cisco IOS and NX-OS Software Reference Guide.

  To determine if the device is acting as a WLC, administrators can log in to the device and use the show wireless interface summary command in the CLI, and then refer to the command output that appears. If the device is acting as a WLC, the output will display configured interfaces.
  
  The following example shows the output of the show wireless interface summary command on a device with one wireless interface configured:
  
  

  3850-4# show wireless interface summary 
  Wireless Interface Summary
  
  Interface Name Interface Type VLAN ID IP Address      IP Netmask     MAC Address
  --------------------------------------------------------------------------------
  Vlan151        Management     151     192.168.151.14  255.255.255.0  d0c7.8956.b24d

  
  

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by this vulnerability.
  
  Cisco has confirmed that this vulnerability does not affect Cisco IOS Software, Cisco IOS XR Software, or Cisco NX-OS 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:
  http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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 upgrade 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:
  http://www.cisco.com/en/US/support/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 should upgrade to Cisco IOS XE Software version 16.3.5.
  
  The software updates can be downloaded from the Software Center on Cisco.com.

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 the resolution of a support case.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-ios-xe

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2017-September-27

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