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AUSCERT External Security Bulletin Redistribution
ESB-2022.1616
Cisco IOS and IOS XE Software Web Services Denial of Service Vulnerability
14 April 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS and IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20697
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-http-dos-svOdkdBS
Comment: CVSS (Max): 8.6 CVE-2022-20697 (CVSS:3.1/AV:N/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:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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Cisco IOS and IOS XE Software Web Services Denial of Service Vulnerability
Priority: High
Advisory ID: cisco-sa-http-dos-svOdkdBS
First Published: 2022 April 13 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvx42406
CVE Names: CVE-2022-20697
CWEs: CWE-691
Summary
o A vulnerability in the web services interface of Cisco IOS Software and
Cisco IOS XE Software could allow an authenticated, remote attacker to
cause a denial of service (DoS) condition.
This vulnerability is due to improper resource management in the HTTP
server code. An attacker could exploit this vulnerability by sending a
large number of HTTP requests to an affected device. 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 no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-http-dos-svOdkdBS
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 Cisco devices if they are running a vulnerable
release of Cisco IOS Software or Cisco IOS XE Software and have the HTTP
feature enabled. All vulnerable releases of Cisco IOS XE Software are
within the 3SE and 3E release trains.
For more information about which Cisco software releases are vulnerable,
see the Fixed Software section of this advisory.
Determine the HTTP Server Configuration
To determine whether the HTTP Server feature is enabled for a device, log
in to the device and use the show running-config | include ip http server|
secure|active command in the CLI to check for the presence of the ip http
server command or the ip http secure-server command in the global
configuration. If either command is present, the HTTP Server feature is
enabled for the device.
The following example shows the output of the show running-config | include
ip http server|secure|active command for a device that has the HTTP Server
feature enabled:
Router# show running-config | include ip http server|secure|active
ip http server
ip http secure-server
Note: The presence of either command or both commands in the device
configuration indicates that the web UI feature is enabled.
If the ip http server command is present and the configuration also
contains ip http active-session-modules none , the vulnerability is not
exploitable over HTTP.
If the ip http secure-server command is present and the configuration also
contains ip http secure-active-session-modules none , the vulnerability is
not exploitable over HTTPS.
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 XR Software
Meraki products
NX-OS Software
Workarounds
o There are no workarounds that address this vulnerability. However, there
are mitigations.
Disabling the HTTP Server feature eliminates the attack vector for this
vulnerability and may be a suitable mitigation until affected devices can
be upgraded. To disable the HTTP Server feature, use the no ip http server
or no ip http secure-server command in global configuration mode. If both
the HTTP server and HTTPS server are in use, both commands are required to
disable the HTTP Server feature.
Disabling HTTP and HTTPS for management functions can also be a suitable
mitigation. Use the ip http active-session-modules none and ip http
secure-active-session-modules none commands.
While these mitigations 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
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-http-dos-svOdkdBS
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-APR-13 |
+----------+---------------------------+----------+--------+--------------+
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