Cisco Security Advisory
Cisco Firepower Threat Defense Software SNMP Denial of Service Vulnerability
A vulnerability in the Simple Network Management Protocol (SNMP) input packet processor of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to restart unexpectedly.
The vulnerability is due to a lack of sufficient memory management protections under heavy SNMP polling loads. An attacker could exploit this vulnerability by sending a high rate of SNMP requests to the SNMP daemon through the management interface on an affected device. A successful exploit could allow the attacker to cause the SNMP daemon process to consume a large amount of system memory over time, which could then lead to an unexpected device restart, causing a denial of service (DoS) condition.
This vulnerability affects all versions of SNMP.
Cisco has released software updates that address this vulnerability. There are 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.
This vulnerability affects Cisco products if they are running a vulnerable release of Cisco FTD Software and SNMP is configured on the device management interface.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine Whether SNMP is Configured
Option 1: Use the CLI
On devices that are running Cisco FTD Software, use the show running-config snmp CLI command. It is available from Diagnostic CLI mode only. To enter Diagnostic CLI mode, use the system support diagnostic-cli command in the regular Cisco FTD CLI. If the snmp-server host management address is configured, the device is considered vulnerable, as shown in the following example:
ftd# show running-config snmp
snmp-server host management 192.168.1.5
Option 2: Use the Firepower Management Center GUI
On devices that are running Cisco Firepower Management Center (FMC) Software, choose Devices > Platform Settings > Enable SNMP Servers. If the interface of an SNMP server in the hosts tab is configured for the Cisco FTD management interface, then the device is considered vulnerable.
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 Cisco Adaptive Security Appliance (ASA) Software or Cisco Firepower Management Center (FMC) Software.
There is a workaround that addresses this vulnerability.
Administrators can disable SNMP polling to the management interface of the Cisco FTD device.
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:
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 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 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/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 6.2.21 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 Not vulnerable. Migrate to a fixed release. 6.4.0 Not vulnerable. Migrate to a fixed release. 6.5.0 Not vulnerable. Migrate to a fixed release. 6.6.0 6.6.1 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 following:
- 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.
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 Santosh Krishnamurthy 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 1.0 Initial public release. - Final 2020-OCT-21
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