Critical Cisco Wireless LAN Controller Management Interface Authentication Bypass Vulnerability

Summary

• A vulnerability in the authentication functionality of Cisco Wireless
  LAN Controller (WLC) Software could allow an unauthenticated, remote
  attacker to bypass authentication controls and log in to the device
  through the management interface

  This vulnerability is due to the improper implementation of the
  password validation algorithm. An attacker could exploit this
  vulnerability by logging in to an affected device with crafted
  credentials. A successful exploit could allow the attacker to bypass
  authentication and log in to the device as an administrator. The
  attacker could obtain privileges that are the same level as an
  administrative user but it depends on the crafted credentials.

  Note: This vulnerability exists because of a
  non-default device configuration that must be present for it to be
  exploitable. For details about the vulnerable configuration, see the Vulnerable Products section of this advisory.

  Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wlc-auth-bypass-JRNhV4fF

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are
  running Cisco WLC Software Release 8.10.151.0 or Release 8.10.162.0 and
  have macfilter radius compatibility configured as Other:

  • 3504 Wireless Controller
  • 5520 Wireless Controller
  • 8540 Wireless Controller
  • Mobility Express
  • Virtual Wireless Controller (vWLC)

  Note: The vulnerable releases noted above are available in the Software Center
  on Cisco.com. In addition, specific customers have been given the
  following vulnerable escalation builds that are not in the Software
  Center:

  • 8.10.151.4 to 8.10.151.10
  • 8.10.162.1 to 8.10.162.14

  Determine the Configuration

  To determine whether the Cisco WLC configuration is vulnerable, issue the show macfilter summary CLI command. If RADIUS compatibility mode is other, as shown in the following example, the device is considered vulnerable:

  wlc > show macfilter summary 
  
  MAC Filter RADIUS Compatibility mode............. Other
  MAC Filter Delimiter............................. Single-Hyphen
  MAC Filter Entries............................... 0
  
  

  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 for Catalyst 9300, 9400, and 9500 Series Switches
  • Catalyst 9800 Series Wireless Controllers
  • Catalyst 9800 Wireless Controller for Cloud
  • Embedded Wireless Controller on Catalyst Access Points
  • Wireless LAN Controller (WLC) AireOS products not listed in the Vulnerable Products section

Workarounds

• There are workarounds that addresses this vulnerability. Choose one of the following based on the environment:

  Option 1: No Macfilters in the Environment

  Customers who do not use macfilters can reset the macfilter radius compatibility mode to the default value using the following CLI command:

  wlc > config macfilter radius-compat cisco

  Option 2: Macfilters in the Environment

  Customers who use macfilters and who are able to change the radius
  server configuration to match other possible compatibility modes can
  modify the macfilter compatibility to either cisco or free using one of the following CLI commands:

  wlc > config macfilter radius-compat cisco
  wlc > config macfilter radius-compat free

  For more information about the different macfilter compatibility modes, see Cisco Wireless Controller Command Reference.

  While these workarounds have been deployed and were proven successful
  in a test environment, customers should determine the applicability and
  effectiveness in their own environment and under their own use
  conditions. Customers should be aware that any workaround or mitigation
  that is implemented may negatively impact the functionality or
  performance of their network based on intrinsic customer deployment
  scenarios and limitations. Customers should not deploy any workarounds
  or mitigations before first evaluating the applicability to their own
  environment and any impact to such environment.

Fixed Software

• Cisco has released free software updates
  that address the vulnerability described in this advisory. Customers
  with service contracts that entitle them to regular software updates
  should obtain security fixes through their usual update channels.

  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.

  The Cisco Support and Downloads page
  on Cisco.com provides information about licensing and downloads. This
  page can also display customer device support coverage for customers who
  use the My Devices tool.

  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 right 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. Customers are advised to
  upgrade to an appropriate fixed software release as indicated in this section.

  Cisco Wireless LAN Controller Release	First Fixed Release
  8.9 and earlier	Not vulnerable
  8.10.142.0 and earlier	Not vulnerable
  8.10.151.0 and later	8.10.171.0

  To download the software from the Software Center on Cisco.com, do the following:

  1. Click Browse all.
  2. Choose Wireless > Wireless LAN Controller > Standalone Controllers.
  3. Choose a specific product from the right pane of the product selector.
  4. Choose a hardware platform from the left pane of the software page.

  The Cisco Product Security Incident Response Team (PSIRT) validates
  only the affected and fixed release information that is documented in
  this advisory.

Exploitation and Public Announcements

• The Cisco PSIRT is not aware of any public announcements or malicious
  use of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank a security researcher with Bispok for reporting this vulnerability.