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AUSCERT External Security Bulletin Redistribution
ESB-2022.1911.2
Cisco Adaptive Security Appliance Software and Firepower Threat Defense
Software Remote Access SSL VPN Denial of Service Vulnerability
11 August 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Adaptive Security Appliance Software
Firepower Threat Defense Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20715
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-dos-tL4uA4AA
Comment: CVSS (Max): 8.6 CVE-2022-20715 (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
Revision History: August 11 2022: Corrected the fixed version information for Cisco FTD Software.
April 29 2022: Initial Release
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco Adaptive Security Appliance Software and Firepower Threat Defense
Software Remote Access SSL VPN Denial of Service Vulnerability
Priority: High
Advisory ID: cisco-sa-asa-dos-tL4uA4AA
First Published: 2022 April 27 16:00 GMT
Last Updated: 2022 August 10 19:07 GMT
Version 1.3: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwa04461
CVE Names: CVE-2022-20715
CWEs: CWE-399
Summary
o A vulnerability in the remote access SSL VPN features of Cisco Adaptive
Security Appliance (ASA) Software and 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 improper validation of errors that are logged
as a result of client connections that are made using remote access VPN. An
attacker could exploit this vulnerability by sending crafted requests to an
affected system. A successful exploit could allow the attacker to cause the
affected 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-asa-dos-tL4uA4AA
This advisory is part of the April 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: April 2022 Cisco
ASA, FMC, and FTD Software Security Advisory Bundled Publication .
Affected Products
o Vulnerable Products
This vulnerability affects Cisco products if they are running a vulnerable
release of Cisco ASA Software or FTD Software and have a vulnerable
AnyConnect or WebVPN configuration.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Cisco ASA Software Configuration
To determine whether the software on a device has a vulnerable feature
configured, use the show-running-config CLI command. In the following
table, the left column lists the Cisco ASA Software features that are
vulnerable. The right column shows the output of the show running-config
CLI command on a device that has the feature enabled. If a device is
running a vulnerable release and has one of these features configured, it
is affected by this vulnerability.
Cisco ASA Software Feature Vulnerable Configuration
webvpn
AnyConnect SSL VPN enable
Clientless SSL VPN webvpn
enable
Determine the Cisco FTD Software Configuration
To determine whether the software on a device has a vulnerable feature
configured, use the show-running-config CLI command. In the following
table, the left column lists the Cisco FTD Software features that are
vulnerable. The right column shows the output of the show running-config
CLI command on a device that has the feature enabled. If a device is
running a vulnerable release and has one of these features configured, it
is affected by this vulnerability.
Cisco FTD Software Feature Vulnerable Configuration
AnyConnect SSL VPN ^1,2 webvpn
enable
1. Remote Access VPN features were introduced in Cisco FTD Software Release
6.2.2.
2. Remote Access VPN features are enabled by choosing Devices > VPN >
Remote Access in Cisco Firepower Management Center (FMC) or by choosing
Device > Remote Access VPN in Cisco Firepower Device Manager (FDM).
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Workarounds
o There are no workarounds that address this vulnerability.
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.
Fixed Releases
In the following table(s), the left column lists Cisco software releases.
The center column indicates whether a release is affected by the
vulnerability described in this advisory and the first release that
includes the fix for this vulnerability. The right column indicates whether
a release is affected by any of the Critical or High SIR vulnerabilities
described in this bundle and which release includes fixes for those
vulnerabilities.
ASA Software
Cisco ASA First Fixed Release First Fixed Release for All
Software for This Vulnerabilities Described in the Bundle
Release Vulnerability of Advisories
9.7 and Not vulnerable. Migrate to a fixed release.
earlier ^1
9.8 Not vulnerable. 9.8.4.44 (June 2022)
9.9 ^1 Not vulnerable. Migrate to a fixed release.
9.10 ^1 Not vulnerable. Migrate to a fixed release.
9.12 Not vulnerable. 9.12.4.38
9.13 ^1 Not vulnerable. Migrate to a fixed release.
9.14 Not vulnerable. 9.14.4
9.15 Not vulnerable. 9.15.1.21
9.16 9.16.2.11 9.16.2.14
9.17 Not vulnerable. 9.17.1.7
1. Cisco ASA Software releases 9.7 and earlier as well as releases 9.9,
9.10, and 9.13 have reached end of software maintenance . Customers are
advised to migrate to a supported release that includes the fix for this
vulnerability.
FTD Software
Cisco First Fixed Release for This Vulnerability First Fixed
FTD Release for All
Software Vulnerabilities
Release Described in the
Bundle of
Advisories
6.2.2
and Not vulnerable. Migrate to a
earlier fixed release.
^1
6.2.3 Not vulnerable. Migrate to a
fixed release.
6.3.0 ^1 Migrate to a fixed release. Migrate to a
fixed release.
6.4.0 6.4.0.13 6.4.0.15 (May
2022)
6.5.0 ^1 Migrate to a fixed release. Migrate to a
fixed release.
6.6.0 6.6.5.2 6.6.5.2
Cisco_FTD_Hotfix_AA-6.7.0.4-2.sh.REL.tar
6.7.0 Cisco_FTD_SSP_FP1K_Hotfix_AA-6.7.0.4-2.sh.REL.tar Migrate to a
Cisco_FTD_SSP_FP2K_Hotfix_AA-6.7.0.4-2.sh.REL.tar fixed release.
Cisco_FTD_SSP_Hotfix_AA-6.7.0.4-2.sh.REL.tar
7.0.0 7.0.2 (May 2022) 7.0.2 (May 2022)
7.1.0 7.1.0 7.1.0.1
1. Cisco FMC and FTD Software releases 6.2.2 and earlier, as well as
releases 6.3.0 and 6.5.0, have reached end of software maintenance .
Customers are advised to migrate to a supported release that includes the
fix for this vulnerability.
For instructions on upgrading your FTD device, see Cisco Firepower
Management Center Upgrade Guide .
The Cisco Product Security Incident Response Team (PSIRT) validates only
the affected and fixed release information that is documented in this
advisory.
Exploitation and Public Announcements
o The Cisco 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 the resolution of a Cisco TAC support
case.
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 Cisco ASA, FMC, and FTD Software Security
Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-dos-tL4uA4AA
Revision History
o +---------+-----------------------------+----------+--------+-------------+
| Version | Description | Section | Status | Date |
+---------+-----------------------------+----------+--------+-------------+
| | Corrected the fixed version | Fixed | | |
| 1.3 | information for Cisco FTD | Software | Final | 2022-AUG-10 |
| | Software. | | | |
+---------+-----------------------------+----------+--------+-------------+
| 1.2 | Corrected CVSS score. | - | Final | 2022-AUG-08 |
+---------+-----------------------------+----------+--------+-------------+
| 1.1 | Updated ASA 9.8 first fixed | Fixed | Final | 2022-JUN-01 |
| | release information. | Software | | |
+---------+-----------------------------+----------+--------+-------------+
| 1.0 | Initial public release. | - | Final | 2022-APR-27 |
+---------+-----------------------------+----------+--------+-------------+
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