Summary

• A vulnerability in the WLAN Control Protocol (WCP) implementation for Cisco Aironet Access Point (AP) software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. 

  This vulnerability is due to incorrect error handling when an affected device receives an unexpected 802.11 frame. An attacker could exploit this vulnerability by sending certain 802.11 frames over the wireless network to an interface on an affected AP. A successful exploit could allow the attacker to cause a packet buffer leak. This could eventually result in buffer allocation failures, which would trigger a reload of the affected 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-airo-wpa-pktleak-dos-uSTyGrL

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco Aironet AP software: 

  • 6300 Series Embedded Services APs
  • Aironet 1540 Series
  • Aironet 1560 Series
  • Aironet 1800 APs
  • Aironet 2800 Series APs
  • Aironet 3800 Series APs
  • Aironet 4800 APs
  • Catalyst 9100 APs
  • Catalyst IW6300 Heavy Duty Series APs
  • Integrated APs on 1100 Integrated Services Routers (ISRs)

  Only the 8.10, 17.2, and 17.3 code trains are vulnerable. For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  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 any Cisco Access Point series that is not listed in the Vulnerable Products section of this advisory.

Indicators of Compromise

• Exploitation of this vulnerability causes the WCP daemon process to unexpectedly restart and the AP to reload. This event would be indicated by the following syslog messages:

  systemd[1]: wcpd.service: main process exited, code=dumped, status=6/ABRT
  systemd[1]: Unit wcpd.service entered failed state.
  systemd[1]: wcpd.service failed.

  To view these syslog messages, use the show logging CLI command. If the AP reloaded unexpectedly and these syslog messages are present, contact Cisco Technical Assistance Center (TAC) to determine if this vulnerability was exploited on the device.

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

  The process to upgrade an AP requires administrators to upgrade the wireless controller to which the AP is registered. Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s):

  Access Points Managed by Wireless LAN Controller or Mobility Express
  

  Cisco Wireless LAN Controller Software Release	First Fixed Release
  8.9 and earlier	Not vulnerable.
  8.10	8.10.162.01

  1. The first vulnerable release is Release 8.10.121.0.

  Access Points Managed by Catalyst 9800 Wireless Controller or Embedded Wireless Controller (EWC) on Catalyst Access Points

  Cisco Catalyst 9800 Wireless Controller Software Release	First Fixed Release
  16.12 and earlier	Not vulnerable.
  17.2	Migrate to a fixed release.1
  17.3	IOS XE Access Point Service Pack 17.03.04.CSCvz178682
  17.4 and later	Not vulnerable.

  1. The first vulnerable release is Release 17.2.1.

  2. The first fixed release for this vulnerability is Release 17.3.4. However, in order to fix this vulnerability and CSCvz08781, the recommendation is to upgrade to Release 17.3.4 and install the IOS XE Access Point Service Pack 17.03.04.CSCvz17868.

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-airo-wpa-pktleak-dos-uSTyGrL

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2021-SEP-22

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