A vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory handling error when GRE over IPv6 traffic is processed. An attacker could exploit this vulnerability by sending crafted GRE over IPv6 packets with either IPv4 or IPv6 payload through an affected device. A successful exploit could allow the attacker to cause the device to crash, 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-ftd-dos-2-sS2h7aWe This advisory is part of the May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication, which includes 12 Cisco Security Advisories that describe 12 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.
A vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
The vulnerability is due to a memory handling error when GRE over IPv6 traffic is processed. An attacker could exploit this vulnerability by sending crafted GRE over IPv6 packets with either IPv4 or IPv6 payload through an affected device. A successful exploit could allow the attacker to cause the device to crash, 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-ftd-dos-2-sS2h7aWe
This advisory is part of the May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication, which includes 12 Cisco Security Advisories that describe 12 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: May 2020 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.
This vulnerability affects Cisco FTD Software releases 6.3.0 and 6.4.0.
Note: GRE tunnel decapsulation in the LINA engine was introduced in Cisco FTD Software Release 6.3.0. This feature is enabled by default and cannot be disabled.
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 Cisco Adaptive Security Appliance (ASA) Software or Cisco Firepower Management Center (FMC) Software.
There are no workarounds that address this vulnerability.
However, as a mitigation, customers can choose to bypass decapsulation for GRE-tunneled flows. To bypass decapsulation, do the following from the FMC GUI:
Note: This configuration will bypass the detection engine for GRE-tunneled traffic.
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/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.
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 providers.
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.
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 Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Earlier than 6.1.01 | Not applicable. | Migrate to a fixed release. |
| 6.1.0 | Not applicable. | Migrate to a fixed release. |
| 6.2.0 | Not applicable. | Migrate to a fixed release. |
| 6.2.1 | Not applicable. | Migrate to a fixed release. |
| 6.2.2 | Not applicable. | Migrate to a fixed release. |
| 6.2.3 | Not applicable. | 6.2.3.16 (June 2020) Cisco_FTD_Hotfix_DT-6.2.3.16-3.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_DT-6.2.3.16-3.sh.REL.tar Cisco_FTD_SSP_Hotfix_DT-6.2.3.16-3.sh.REL.tar |
| 6.3.0 | 6.3.0.5 | 6.3.0.6 (future release) Cisco_FTD_Hotfix_AO-6.3.0.6-2.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_ AO-6.3.0.6-2.sh.REL.tar Cisco_FTD_SSP_Hotfix_ AO-6.3.0.6-2.sh.REL.tar |
| 6.4.0 | 6.4.0.6 | 6.4.0.9 |
| 6.5.0 | Not vulnerable. | 6.5.0.5 (future release) Cisco_FTD_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_FP1K_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_FP2K_Hotfix_H-6.5.0.5-2.sh.REL.tar and later Cisco_FTD_SSP_Hotfix_H-6.5.0.5-2.sh.REL.tar and later |
| 6.6.0 | Not vulnerable. | 6.6.0 |
1. Cisco FMC and FTD Software releases 6.0.1 and earlier 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, customers can do one of the following:
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.
This vulnerability was found by Sanmith Prakash of Cisco during internal security testing.
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 |
|---|---|---|---|---|
| 1.1 | Updated Hot Fixes for releases 6.4.0 and 6.5.0. | Fixed Releases | Final | 2020-MAY-15 |
| 1.0 | Initial public release. | - | Final | 2020-MAY-06 |
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