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AUSCERT External Security Bulletin Redistribution
ESB-2022.5771
Cisco Firepower Threat Defense Software SSL Decryption
Policy Bleichenbacher Attack 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-2022-20940
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-tls-bb-rCgtmY2
Comment: CVSS (Max): 5.3 CVE-2022-20940 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
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:U/C:L/I:N/A:N
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Cisco Firepower Threat Defense Software SSL Decryption Policy Bleichenbacher
Attack Vulnerability
Priority: Medium
Advisory ID: cisco-sa-ftd-tls-bb-rCgtmY2
First Published: 2022 November 9 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwa41936
CVE Names: CVE-2022-20940
CWEs: CWE-203
Summary
o A vulnerability in the TLS handler of Cisco Firepower Threat Defense (FTD)
Software could allow an unauthenticated, remote attacker to gain access to
sensitive information.
This vulnerability is due to improper implementation of countermeasures
against a Bleichenbacher attack on a device that uses SSL decryption
policies. An attacker could exploit this vulnerability by sending crafted
TLS messages to an affected device, which would act as an oracle and allow
the attacker to carry out a chosen-ciphertext attack. A successful exploit
could allow the attacker to perform cryptanalytic operations that may allow
decryption of previously captured TLS sessions to the affected device.
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-tls-bb-rCgtmY2
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
At the time of publication, this vulnerability affected Cisco devices if
they were running a vulnerable release of Cisco FTD Software and had at
least one active SSL decryption policy with the behavior in response to
decryption errors set to Block with reset .
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the SSL Decryption Policy Configuration
In the Cisco Firepower Management Center (FMC) GUI, choose Policies > SSL .
For each configured SSL policy, do the following:
1. Click Edit .
2. Choose the Undecryptable Actions tab.
3. Review the setting for Decryption Errors .
If Decryption Errors is set to Block with reset for an SSL policy, devices
that have that policy applied are affected by this vulnerability.
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
FMC Software
Next-Generation Intrusion Prevention System (NGIPS) Software
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o 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.
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 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: 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-tls-bb-rCgtmY2
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-NOV-09 |
+----------+---------------------------+----------+--------+--------------+
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