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AUSCERT External Security Bulletin Redistribution
ESB-2023.6375
Cisco Firepower Threat Defense Software SMB Protocol Snort 3 Detection
Engine Bypass and Denial of Service Vulnerability
2 November 2023
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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-2023-20270
Original Bulletin:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-smbsnort3-dos-pfOjOYUV
Comment: CVSS (Max): 5.8 CVE-2023-20270 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L)
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:L
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Cisco Firepower Threat Defense Software SMB Protocol Snort 3 Detection Engine
Bypass and Denial of Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-ftd-smbsnort3-dos-pfOjOYUV
First Published: 2023 November 1 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwe19286
CVE Names: CVE-2023-20270
Summary
o A vulnerability in the interaction between the Server Message Block (SMB)
protocol preprocessor and the Snort 3 detection engine for Cisco Firepower
Threat Defense (FTD) Software could allow an unauthenticated, remote
attacker to bypass the configured policies or cause a denial of service
(DoS) condition on an affected device.
This vulnerability is due to improper error-checking when the Snort 3
detection engine is processing SMB traffic. An attacker could exploit this
vulnerability by sending a crafted SMB packet stream through an affected
device. A successful exploit could allow the attacker to cause the Snort
process 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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-smbsnort3-dos-pfOjOYUV
This advisory is part of the November 2023 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 2023
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 Cisco FTD Software Release 7.1.0 or later and if they
were configured with an SMB policy that invokes the Snort 3 detection
engine.
For more information about which Cisco software releases are vulnerable,
see the Fixed Software section of this advisory.
Determine the Snort 3 Configuration
To determine whether Snort 3 is running on Cisco FTD Software, see
Determine the Active Snort Version that Runs on Firepower Threat Defense
(FTD) . Snort 3 must be active for this vulnerability to be exploited.
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
Open Source Snort 2
Open Source Snort 3
Details
o The following Cisco FTD Software Snort 3 configuration parameters govern
how traffic is handled if the Snort 3 process restarts, which could change
how SMB traffic is handled during an exploit of this vulnerability:
Snort Fail Open
snort preserve-connection
For additional information, see the Firepower Management Center
Configuration Guide .
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 .
[2 ] [ ] [Critical,High,Medium]
[Only this advisory ] [Cisco ASA Software]
[Any Platform ]
[ ] [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.
Subscribe to Cisco Security Notifications
o Subscribe
Related to This Advisory
o Cisco Event Response: November 2023 Cisco ASA, FMC, and FTD Software
Security Advisory Bundled Publication
URL
o https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-smbsnort3-dos-pfOjOYUV
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2023-NOV-01 |
+----------+---------------------------+----------+--------+--------------+
Legal Disclaimer
o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT
OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information
or contain factual errors. The information in this document is intended for
end users of Cisco products.
- --------------------------END INCLUDED TEXT--------------------
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