Summary

• A vulnerability in the 802.11r Fast Transition feature set of Cisco IOS Access Points (APs) Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected device.

  The vulnerability is due to a corruption of certain timer mechanisms triggered by specific roaming events. This corruption will eventually cause a timer crash. An attacker could exploit this vulnerability by sending malicious reassociation events multiple times to the same AP in a short period of time, causing a DoS condition on the affected AP.

  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-20181017-ap-ft-dos

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Access Points that are running an affected version of Cisco IOS Access Point Software.

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

  Determining the Cisco Access Point Software Release

  To determine which Cisco Access Point Software release is running on a device, administrators can use the controller's web interface or the CLI.

  To use the controller's web interface, do the following:

  1. Log in to the controller’s web interface
  2. Click the Monitor tab
  3. Click Summary in the left pane
  4. Under Controller Summary, the Software Version field shows the release number of the software that is currently running on the device

  To use the Access Point CLI, log in to the Access Point through a Telnet session. Issue the show version | include IOS command, and then refer to the output of the command. The following example shows the output of a Cisco Access Point that is running Cisco IOS Software Release 15.3(3)JA12.

  AP# show version | include IOS
  
  Cisco IOS Software, C1600 Software (AP1G2-K9W8-M),
  
  Version 15.3(3)JA12, RELEASE SOFTWARE (fc2)
  
  AP#
  
  

  Products Confirmed Not Vulnerable

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

  Cisco Access Points that are running AP-COS Software are not affected by 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 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

  Cisco has released fixed software that addresses this vulnerability.

  To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:

  • cisco-sa-20181017-wlc-gui-privesc: Cisco Wireless LAN Controller Software GUI Privilege Escalation Vulnerability
  • cisco-sa-20181017-ap-ft-dos: Cisco IOS Access Points Software 802.11r Fast Transition Denial of Service Vulnerability
  • cisco-sa-20181017-wlc-capwap-memory-leak: Cisco Wireless LAN Controller Software Control and Provisioning of Wireless Access Points Protocol Information Disclosure Vulnerability
  • cisco-sa-20181017-wlc-capwap-dos: Cisco Wireless LAN Controller Software Control and Provisioning of Wireless Access Points Protocol Denial of Service Vulnerability

  Customers should upgrade to an appropriate release as indicated in the table in this section. In the following table, the first column lists major releases of Cisco Wireless LAN Controller Software, the second column lists the first fixed release of Cisco Wireless LAN Controller Software for the vulnerability described in this advisory, and the third column lists the corresponding Cisco AP IOS Software first fixed release for the vulnerability described in this advisory.

  Cisco WLC Major Software Release	Cisco WLC First Fixed Release for This Vulnerability	Cisco AP IOS First Fixed Release for This Vulnerability
  Prior to 8.0	Vulnerable, migrate to 8.3.140.0 or later	Vulnerable, migrate to 15.3(3)JD13 or later
  8.1	Vulnerable, migrate to 8.3.140.0 or later	Vulnerable, migrate to 15.3(3)JD13 or later
  8.2	Vulnerable, migrate to 8.3.140.0 or later	Vulnerable, migrate to 15.3(3)JD13 or later
  8.3	Vulnerable, migrate to 8.3.140.0 or later	Vulnerable, migrate to 15.3(3)JD13 or later
  8.4	Vulnerable, migrate to 8.5.110.0 or later	Vulnerable, migrate to 15.3(3)JF4 or later
  8.5	Vulnerable, migrate to 8.5.110.0 or later	Vulnerable, migrate to 15.3(3)JF4 or later
  8.6	Not vulnerable	Not vulnerable
  8.7	Not vulnerable	Not vulnerable
  8.8	Not vulnerable	Not vulnerable

  
  

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 Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181017-ap-ft-dos

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2018-October-17

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