Cisco Security Advisory
Cisco Wireless LAN Controller Software Control and Provisioning of Wireless Access Points Protocol Denial of Service Vulnerability
A vulnerability in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol component of Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper input validation on fields within CAPWAP Discovery Request packets by the affected device. An attacker could exploit this vulnerability by sending malicious CAPWAP Discovery Request packets to the Cisco WLC Software. A successful exploit could allow the attacker to cause the Cisco WLC Software to disconnect associated access points (APs). While the APs disconnect and reconnect, service will be unavailable for a brief period of time, resulting in a DoS condition.
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:
This vulnerability affects Cisco WLC devices that are running a software release prior to the first fixed release.
For information about which Cisco WLC Software releases are vulnerable, see the Fixed Software section of this advisory.
Determining the Cisco WLC Software Release
To determine which Cisco WLC Software release is running on a device, administrators can use the controller’s web interface or the CLI.
To use the web interface, do the following:
- By using a browser, log in to the controller’s web interface
- Click the Monitor tab
- Click Summary in the left pane
- Under Controller Summary, the Software Version field shows the release number of the software that is currently running on the device
To use the CLI, log in to the controller via Telnet, issue the show sysinfo command, and then refer to the value in the Product Version field of the command output. The following example shows the command output for a device that is running Cisco WLC Software Release 188.8.131.52:
(wlc)> show sysinfo Manufacturer's Name.............................. Cisco Systems Inc. Product Name..................................... Cisco Controller Product Version.................................. 184.108.40.206 Bootloader Version............................... 1.0.1
Field Recovery Image Version..................... 220.127.116.11 Firmware Version................................. FPGA 1.3, Env 1.6, USB console 1.27 Build Type....................................... DATA + WPS . . .
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by these vulnerabilities.
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:
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:
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.
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 left column lists major releases of Cisco software, and the center column indicates the first minor release that includes the fix for this vulnerability. The right column indicates which release is recommended to address this vulnerability.
Cisco Wireless LAN Controller Major Software Release First Fixed Release for This Vulnerability Recommended Release for This Vulnerability Prior to 8.0
18.104.22.168 22.214.171.124 8.0 126.96.36.199 188.8.131.52
8.1 184.108.40.206 220.127.116.11
18.104.22.168 8.4 22.214.171.124 126.96.36.199
188.8.131.52 8.8 Not vulnerable
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.
This vulnerability was found during internal security testing.
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.
Version Description Section Status Date 1.1 Corrected fix information for WLC releases prior to 8.0 and Release 8.0. Fixed Software Final 2018-October-22 1.0 Initial public release. - Final 2018-October-17
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