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AUSCERT External Security Bulletin Redistribution
Cisco Firepower 2100 Series SSL/TLS Inspection Denial of
23 October 2020
AusCERT Security Bulletin Summary
Product: Cisco Firepower 2100 Series
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-3562
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Cisco Firepower 2100 Series SSL/TLS Inspection Denial of Service Vulnerability
Advisory ID: cisco-sa-ftd-ssl-dcrpt-dos-RYEkX4yy
First Published: 2020 October 21 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvs56802
o A vulnerability in the SSL/TLS inspection of Cisco Firepower Threat Defense
(FTD) Software for Cisco Firepower 2100 Series firewalls could allow an
unauthenticated, remote attacker to cause a denial of service (DoS)
condition on an affected device.
The vulnerability is due to improper input validation for certain fields of
specific SSL/TLS messages. An attacker could exploit this vulnerability by
sending a malformed SSL/TLS message through an affected device. A
successful exploit could allow the attacker to cause the affected device to
reload, resulting in a DoS condition. No manual intervention is needed to
recover the device after it has reloaded.
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:
This advisory is part of the October 2020 Cisco ASA, FMC, and FTD Software
Security Advisory Bundled Publication, which includes 17 Cisco Security
Advisories that describe 17 vulnerabilities. For a complete list of the
advisories and links to them, see Cisco Event Response: October 2020 Cisco
ASA, FMC, and FTD Software Security Advisory Bundled Publication .
o Vulnerable Products
This vulnerability affects Cisco Firepower 2100 Series firewalls if they
are running a vulnerable release of Cisco FTD Software and have the SSL/TLS
inspection feature enabled.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
See the Firepower Management Center Configuration Guide for information
about configuring SSL/TLS inspection policies.
To determine whether SSL/TLS inspection is enabled, choose one of the
Option 1: Use the CLI
Use the show ssl-policy-config CLI command to determine whether SSL/TLS
inspection is enabled on a device. The following example shows the output
of the show ssl-policy-config command on a device that does not have an SSL
policy configured and is not vulnerable:
> show ssl-policy-config
SSL policy not yet applied.
Any other output returned by the show ssl-policy-config command indicates
that SSL/TLS inspection is configured and the device is vulnerable.
See the Cisco Firepower Threat Defense Command Reference for further
information about the show ssl-policy-config command.
Option 2: Use the GUI
To verify whether SSL/TLS inspection is enabled on a device, navigate
through the following menus:
For devices managed by Firepower Management Center (FMC) : Policies >
Access Control > SSL
For devices managed by Firepower Device Manager (FDM) : Policies > SSL
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
Adaptive Security Appliance (ASA) Software
Firepower Management Center (FMC) Software
FTD Software that is running on any platform other than the platforms
that are listed in the Vulnerable Products section of this advisory
o There are no workarounds that address this vulnerability.
o 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: https://www.cisco.com/c/en/us/products/
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
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
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
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 vulnerabilities described in this
bundle and which release includes fixes for those vulnerabilities.
Cisco FTD Software
Cisco FTD First Fixed Release First Fixed Release for All
Software for This Vulnerabilities Described in the Bundle
Release Vulnerability of Advisories
Earlier than Not vulnerable. Migrate to a fixed release.
6.2.2 Not vulnerable. Migrate to a fixed release.
6.2.3 Not vulnerable. Migrate to a fixed release.
6.3.0 Migrate to a fixed Migrate to a fixed release.
6.4.0 Migrate to a fixed Migrate to a fixed release.
6.5.0 Migrate to a fixed Migrate to a fixed release.
6.6.0 Not vulnerable. 6.6.1
1. Cisco FMC and FTD Software releases 6.0.1 and earlier, as well as
releases 6.2.0 and 6.2.1, have reached end of software maintenance.
Customers are advised to migrate to a supported release that includes the
fix for this vulnerability.
To upgrade to a fixed release of Cisco FTD Software, do one of the
For devices that are managed by using Cisco Firepower Management Center
(FMC), use the FMC interface to install the upgrade. After installation
is complete, reapply the access control policy.
For devices that are managed by using Cisco Firepower Device Manager
(FDM), use the FDM interface to install the upgrade. After installation
is complete, reapply the access control policy.
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.
o This vulnerability was found by Sanmith Prakash of Cisco during internal
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.
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | - | Final | 2020-OCT-21 |
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