A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco Wireless LAN Controllers could allow an authenticated, remote attacker to cause an affected device to restart, resulting in a denial of service (DoS) condition. The vulnerability is due to a memory leak that occurs on an affected device after the device fails to deallocate a buffer that is used when certain MIBs are polled. An attacker who knows the SNMP Version 2 SNMP Read string or has valid SNMP Version 3 credentials for an affected device could repeatedly poll the affected MIB object IDs (OIDs) and consume available memory on the device. When memory is sufficiently depleted on the device, the device will restart, 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: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171101-wlc1
This vulnerability affects Cisco Wireless LAN Controllers (WLCs) that have SNMP enabled and are running a vulnerable release of Cisco WLC Software.
For information about which Cisco WLC Software releases are vulnerable, see the Fixed Software section of this advisory.
To determine whether SNMP is enabled on a device, administrators can issue the show run-config command in the CLI. If the output of the command indicates that the config snmp <1|2|3> enable command is present in the running configuration, SNMP is enabled on the device.
To determine which release of Cisco WLC Software is running on a device, administrators can use the web interface or the CLI.
To use the web interface, log in to the web interface, click the Monitor tab, and then click Summary in the left pane. The Software Version field shows the release number of the software that is currently running on the device.
To use the CLI, 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 output of the command for a device that is running Cisco WLC Software Release 8.3.102.0:
Vulmon
(wlc)> show sysinfo
Manufacturer's Name.............................. Cisco Systems Inc.
Product Name..................................... Cisco Controller
Product Version.................................. 8.3.102.0
Bootloader Version............................... 1.0.1
Field Recovery Image Version..................... 6.0.182.0
Firmware Version................................. FPGA 1.3, Env 1.6, USB console 1.27
Build Type....................................... DATA + WPS
.
.
.
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:
http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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:
http://www.cisco.com/en/US/support/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.
Customers should upgrade to an appropriate release as indicated in the table in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
In the following table, the left column lists releases of Cisco software. The center column indicates the first recommended release that includes the fix for this vulnerability. The right column indicates the first recommended release that includes fixes for all the vulnerabilities described in this collection of advisories.
| Cisco Wireless LAN Controller Software Release | Recommended Fixed Release for This Vulnerability | Recommended Fixed Release for All the Vulnerabilities Described in the Collection of Advisories |
|---|---|---|
| Prior to 8.0 | 8.0.152.0 | 8.0.152.0 |
| 8.0 | 8.0.152.0 | 8.0.152.0 |
| 8.1 | 8.2.166.0 | 8.2.166.0 |
| 8.2 | 8.2.166.0 | 8.2.166.0 |
| 8.3 | 8.3.133.0 | 8.3.133.0 |
| 8.4 | 8.4.100.0 | 8.4.100.0 |
| 8.5 | 8.5.110.0 (future release) | 8.5.110.0 (future release) |
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.
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 | WLC Releases 8.2 and 8.3 were rebuilt to address customer issues. The recommended releases have been updated. | Fixed Software | Final | 2017-November-02 |
| 1.0 | Initial public release. | - | Final | 2017-November-01 |
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