Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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A vulnerability in the 802.11 Generic Advertisement Service (GAS) frame processing function of Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS).
The vulnerability is due to incomplete input validation of the 802.11 GAS frames that are processed by an affected device. An attacker could exploit this vulnerability by sending a crafted 802.11 GAS frame over the air to an access point (AP), and that frame would then be relayed to the affected WLC. Also, an attacker with Layer 3 connectivity to the WLC could exploit this vulnerability by sending a malicious 802.11 GAS payload in a Control and Provisioning of Wireless Access Points (CAPWAP) packet to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS.
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-wlc-gas-dos-8FsE3AWHThis advisory is part of the April 2020 Cisco Aironet AP, Mobility Express, and WLC Software Security Advisory Bundled Publication, which includes four Cisco Security Advisories that describe four vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: April 2020 Cisco Aironet AP, Mobility Express and WLC Software Security Advisory Bundled Publication.
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Vulnerable Products
This vulnerability affects Cisco devices if they are running a vulnerable release of Cisco WLC Software and have at least one WLAN with the HotSpot2.0 feature enabled.
Note: The HotSpot2.0 feature is enabled individually on each WLAN.
For more information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine Whether HotSpot2.0 Is Enabled Using the GUI
To determine whether HotSpot2.0 is enabled, do the following from the WLC GUI:
- Choose the WLANs tab.
- For each WLAN on the list, mouse over the blue drop-down arrow and click HotSpot2.0.
- Verify whether the Hotspot2 Enable checkbox is checked.
Determine Whether HotSpot2.0 Is Enabled Using the CLI
To determine whether HotSpot2.0 is enabled, issue the CLI command show wlan wlan_id for each configured WLAN. The following example shows the output of the show wlan wlan_id command for a WLAN that has HotSpot2.0 enabled:
--More-- or (q)uit
802.11u........................................ Enabled
Network Access type............................ Chargeable Public Network
Internet service............................... Enabled
Network Authentication type.................... Not Applicable
HESSID......................................... 00:00:00:00:00:00
IP Address Type Configuration
IPv4 Address type............................ Available
IPv6 Address type............................ Not Known
Hotspot 2.0.................................... EnabledProducts 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 Cisco Catalyst 9800 Series Wireless Controllers.
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There are no workarounds that address this vulnerability.
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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
In the following table, the left column lists Cisco software releases. The center 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. The right column indicates whether a release is affected by all the vulnerabilities described in this bundle of advisories and which release includes fixes for those vulnerabilities.
Cisco WLC Major Software Release First Fixed Release for This Vulnerability Recommended Release for All Vulnerabilities Described in This Bundle of Advisories 8.5 and earlier 8.5.160.0 8.5.161.01 8.6 8.8.130.0 8.8.130.0 8.7 8.8.130.0 8.8.130.0 8.8 8.8.130.0 8.8.130.0 8.9 8.10.112.0 8.10.121.0 8.10 8.10.112.0 8.10.121.0 1. If the deployment is based on a Mobility Express controller, Cisco recommends migrating to Release 8.8.130.0.
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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.
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This vulnerability was found by Mathieu Monney of Cisco during internal security testing.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.1 Updated first fixed release for releases 8.9 and 8.10. Fixed Releases Final 2020-APR-20 1.0 Initial public release. — Final 2020-APR-15
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