Cisco Security Advisory
Multiple Cisco Products Snort TCP Fast Open File Policy Bypass Vulnerability
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
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Multiple Cisco products are affected by a vulnerability with TCP Fast Open (TFO) when used in conjunction with the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP.
The vulnerability is due to incorrect detection of the HTTP payload if it is contained at least partially within the TFO connection handshake. An attacker could exploit this vulnerability by sending crafted TFO packets with an HTTP payload through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.
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-snort-tfo-bypass-MmzZrtes
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Vulnerable Products
At the time of publication, this vulnerability affected the following Cisco products if they were running releases earlier than the first fixed release of Cisco software:
- 1000 Series Integrated Services Routers (ISRs)
- 3000 Series Industrial Security Appliances (ISAs)
- 4000 Series Integrated Services Routers (ISRs)
- Cloud Services Router 1000V
- Firepower Threat Defense (FTD) Software
- Integrated Services Virtual Router (ISRv)
- Meraki MX64
- Meraki MX64W
- Meraki MX67
- Meraki MX67C
- Meraki MX67W
- Meraki MX68
- Meraki MX68CW
- Meraki MX68W
- Meraki MX100
- Meraki MX84
- Meraki MX250
- Meraki MX450
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
This vulnerability also affected all open source Snort project releases earlier than Release 2.9.17. For more information, see the Snort website.
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
- Meraki vMX100 Virtual Appliances
- Meraki Z1 Appliances
- Meraki Z3 Series Appliances
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There are no workarounds that address this vulnerability.
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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.
Fixed Releases
At the time of publication, Cisco Firepower Threat Defense (FTD) releases 6.7.0 and later contained the fix for this vulnerability when the Snort 2 option is configured.
At the time of publication, there were no fixes for Cisco FTD for this vulnerability when the Snort 3 option is configured.
At the time of publication, Cisco UTD Snort IPS Engine Software for IOS XE 17.4.11 contained the fix for this vulnerability.
At the time of publication, Cisco had not released software updates that address this vulnerability for Meraki MX Series Security Appliances.
At the time of publication, the open source Snort project release 2.9.17 and later contained the fix for this vulnerability. For more information, see the Snort website.
At the time of publication, there were no fixes for open source Snort project release 3.0. For more information, see the Snort website.
See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
1. Starting in 17.2.1, IOS XE and IOS XE SD-WAN use the same image file.
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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.
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Cisco would like to thank Guillermo Muñoz Mozos of BBVA for reporting this vulnerability.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2021-JAN-13
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