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AUSCERT External Security Bulletin Redistribution
ESB-2022.1613
Cisco IOS XE Wireless Controller Software for the Catalyst
9000 Family SNMP Trap Denial of Service Vulnerability
14 April 2022
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Wireless Controller Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20684
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-c9800-snmp-trap-dos-mjent3Ey
Comment: CVSS (Max): 7.4 CVE-2022-20684 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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Cisco IOS XE Wireless Controller Software for the Catalyst 9000 Family SNMP
Trap Denial of Service Vulnerability
Priority: High
Advisory ID: cisco-sa-c9800-snmp-trap-dos-mjent3Ey
First Published: 2022 April 13 16:00 GMT
Version 1.0: Final
Workarounds: Yes
Cisco Bug IDs: CSCvs71784
CVE Names: CVE-2022-20684
CWEs: CWE-190
Summary
o A vulnerability in Simple Network Management Protocol (SNMP) trap
generation for wireless clients of Cisco IOS XE Wireless Controller
Software for the Catalyst 9000 Family could allow an unauthenticated,
adjacent attacker to cause an affected device to unexpectedly reload,
resulting in a denial of service (DoS) condition on the device.
This vulnerability is due to a lack of input validation of the information
used to generate an SNMP trap related to a wireless client connection
event. An attacker could exploit this vulnerability by sending an 802.1x
packet with crafted parameters during the wireless authentication setup
phase of a connection. A successful exploit could allow the attacker to
cause the device to reload, resulting in a DoS condition.
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-c9800-snmp-trap-dos-mjent3Ey
This advisory is part of the April 2022 release of the Cisco IOS and IOS XE
Software Security Advisory Bundled Publication. For a complete list of the
advisories and links to them, see Cisco Event Response: April 2022
Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
Publication.
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco devices if they are running
a vulnerable release of Cisco IOS XE Wireless Controller Software for the
Catalyst 9000 Family and are configured to send SNMP traps for wireless
client exclusion events (disabled by default):
Catalyst 9800 Embedded Wireless Controllers for Catalyst 9300, 9400,
and 9500 Series Switches
Catalyst 9800 Series Wireless Controllers
Catalyst 9800-CL Wireless Controllers for Cloud
Embedded Wireless Controllers on Catalyst Access Points
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
To determine whether any SNMP trapflags for client exclusion events are
enabled on a device, log in to the device and run the show running-config |
include trapflags client excluded command on the CLI to check for the
presence of the trapflags client excluded command in the global
configuration. If any output is returned, then the device is considered
vulnerable.
The following example shows the output of the show running-config | include
trapflags client excluded command for a device that has SNMP client event
trapflags configured:
Router# show running-config | include trapflags client excluded
trapflags client excluded
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:
IOS Software
IOS XR Software
Meraki products
NX-OS Software
Wireless LAN Controller (WLC) AireOS Software
Workarounds
o Customers who do not require SNMP traps for wireless-excluded clients can
disable them from the CLI with the global configuration command, as shown
in the following example:
WLC(config)#no trapflags client excluded
While this workaround has been deployed and was 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
o 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.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
following ways:
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
Exploitation and Public Announcements
o 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
o This vulnerability was found during internal security testing.
Cisco Security Vulnerability Policy
o 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.
Related to This Advisory
o Cisco Event Response: April 2022 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-c9800-snmp-trap-dos-mjent3Ey
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-APR-13 |
+----------+---------------------------+----------+--------+--------------+
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