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AUSCERT External Security Bulletin Redistribution
ESB-2022.5768
Cisco Firepower Threat Defense Software Generic Routing
Encapsulation Denial of Service Vulnerability
10 November 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Firepower Threat Defense Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20946
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-gre-dos-hmedHQPM
Comment: CVSS (Max): 8.6 CVE-2022-20946 (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 Firepower Threat Defense Software Generic Routing Encapsulation Denial of
Service Vulnerability
Priority: High
Advisory ID: cisco-sa-ftd-gre-dos-hmedHQPM
First Published: 2022 November 9 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwb66761
CVE Names: CVE-2022-20946
CWEs: CWE-122
Summary
o A vulnerability in the generic routing encapsulation (GRE) tunnel
decapsulation feature of Cisco Firepower Threat Defense (FTD) Software
could allow an unauthenticated, remote attacker to cause a denial of
service (DoS) condition on an affected device.
This vulnerability is due to a memory handling error that occurs when GRE
traffic is processed. An attacker could exploit this vulnerability by
sending a crafted GRE payload through an affected device. A successful
exploit could allow the attacker to cause the device to 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-ftd-gre-dos-hmedHQPM
This advisory is part of the November 2022 release of the Cisco ASA, FTD,
and FMC Security Advisory Bundled publication. For a complete list of the
advisories and links to them, see Cisco Event Response: November 2022
Semiannual Cisco ASA, FMC, and FTD Software Security Advisory Bundled
Publication .
Affected Products
o Vulnerable Products
This vulnerability affects Cisco FTD Software releases 6.3.0 and later.
Note: GRE tunnel decapsulation in the LINA engine was introduced in Cisco
FTD Software Release 6.3.0. This feature is enabled by default and cannot
be disabled.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
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:
Adaptive Security Appliance (ASA) Software
Firepower Management Center (FMC) Software
Next-Generation Intrusion Prevention System (NGIPS) Software
Workarounds
o There are no workarounds that address this vulnerability.
However, administrators may choose to bypass decapsulation for GRE-tunneled
flows by following these steps from the Cisco FMC GUI:
1. Click Policies and choose Prefilter under Access Control .
2. Click Edit under the Prefilter Policy that is associated with the
access policy assigned to the device.
3. Change the GRE tunnel rule type action to Fastpath .
4. Click Save .
5. Click Deploy .
Note: This configuration will bypass the detection engine for GRE-tunneled
traffic.
While this mitigation 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 ASA, FMC, and FTD Software
To help customers determine their exposure to vulnerabilities in Cisco ASA,
FMC, and FTD Software, Cisco provides the Cisco Software Checker . This
tool identifies any Cisco security advisories that impact a specific
software release and the earliest release that fixes the vulnerabilities
that are described in each advisory ("First Fixed"). If applicable, the
tool also returns the earliest release that fixes all the vulnerabilities
that are described in all the advisories that the Software Checker
identifies ("Combined First Fixed").
To use the tool, go to the Cisco Software Checker page and follow the
instructions. Alternatively, use the following form to search for
vulnerabilities that affect a specific software release. To use the form,
follow these steps:
1. Choose which advisories the tool will search-all advisories, only
advisories with a Critical or High Security Impact Rating (SIR) , or
only this advisory.
2. Choose the appropriate software.
3. Choose the appropriate platform.
4. Enter a release number-for example, 9.16.2.11 for Cisco ASA Software or
6.6.7 for Cisco FTD Software.
5. Click Check .
For instructions on upgrading your FTD device, see Cisco Firepower
Management Center Upgrade Guide .
Additional Resources
For help determining the best Cisco ASA, FTD, or FMC Software release, see
the following Recommended Releases documents. If a security advisory
recommends a later release, Cisco recommends following the advisory
guidance.
Cisco ASA Compatibility
Cisco Secure Firewall ASA Upgrade Guide
Cisco Secure Firewall Threat Defense Compatibility Guide
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 by Satheeshkumar Eswaramoorthy of Cisco 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: November 2022 Semiannual Cisco ASA, FMC, and FTD
Software Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-gre-dos-hmedHQPM
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-NOV-09 |
+----------+---------------------------+----------+--------+--------------+
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