A vulnerability in the FTP inspection engine of Cisco Adaptive Security (ASA) Software and 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 insufficient validation of FTP data. An attacker could exploit this vulnerability by sending malicious FTP traffic through an affected device. A successful exploit could allow the attacker to cause a DoS condition on 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-20191002-asa-dos This advisory is part of the October 2019 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication, which includes 10 Cisco Security Advisories that describe 18 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: October 2019 Cisco ASA, FMC, and FTD Software Security Advisory Bundled Publication.
A vulnerability in the FTP inspection engine of Cisco Adaptive Security (ASA) Software and 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 insufficient validation of FTP data. An attacker could exploit this vulnerability by sending malicious FTP traffic through an affected device. A successful exploit could allow the attacker to cause a DoS condition on 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-20191002-asa-dos
This vulnerability affects Cisco products if they are running a vulnerable release of Cisco ASA Software or Cisco FTD Software that is configured to perform FTP inspection.
FTP inspection is enabled by default in Cisco FTD Software. For detailed information about the default settings for application inspection policies, see the Cisco ASA Series Firewall CLI Configuration Guide.
To determine whether FTP inspection is enabled on an ASA, administrators can use the show running-config policy-map command and then the show running-config service-policy command.
First use the show running-config policy-map command, and check whether the inspect ftp command is present in at least one policy map. In the following output, the global-policy policy map includes the inspect ftp command:
asa# show running-config policy-map ! policy-map global_policy class inspection_default inspect ip-options inspect netbios inspect rtsp inspect sunrpc inspect tftp inspect xdmcp inspect dns preset_dns_map inspect ftp inspect h423 h425
Next use the show running-config service-policy command, and check whether the policy map is applied, either globally or to a single interface. The following output shows the global-policy policy map applied globally:
asa# show running-config service-policy service-policy global_policy global
If the policy map that contains the inspect ftp command is applied globally or to an interface, FTP inspection is enabled.
To determine whether FTP inspection is enabled on FTD, administrators can do one of the following:
For information about which Cisco ASA Software and FTD Software releases are vulnerable, see the Fixed Software section of this advisory.
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 FMC Software.
There are no workarounds that address this vulnerability.
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.
Cisco ASA Software
| Cisco ASA Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| Earlier than 9.41 |
Migrate to a fixed release. | Migrate to a fixed release. |
| 9.41 | Migrate to a fixed release. | Migrate to a fixed release. |
| 9.51 | Migrate to a fixed release. | Migrate to a fixed release. |
| 9.6 | 9.6.4.34 | 9.6.4.34 |
| 9.71 | Migrate to a fixed release. | Migrate to a fixed release. |
| 9.8 | 9.8.4.10 | 9.8.4.10 |
| 9.9 | 9.9.2.56 | Migrate to a fixed release. |
| 9.10 | 9.10.1.30 | 9.10.1.30 |
| 9.12 | 9.12.2.52 | 9.12.2.5 |
| 9.13 | Not vulnerable. | Not vulnerable. |
1. Cisco ASA Software releases 9.5 and earlier, as well as Release 9.7, have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.
2. This vulnerability was first addressed in release 9.12.2.4. Release 9.12.2.4 was deferred and removed from CCO. Customers running release 9.12.2.4 are not affected by this vulnerability. Customers running on a Firepower 2100 Series Appliance should consider upgrading to a non-deferred release.
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 | Migrate to a fixed release. | Migrate to a fixed release. |
| 6.1.0 | Migrate to a fixed release. | Migrate to a fixed release. |
| 6.2.0 | Migrate to a fixed release. | Migrate to a fixed release. |
| 6.2.1 | Migrate to a fixed release. | Migrate to a fixed release. |
| 6.2.2 | Migrate to a fixed release. | Migrate to a fixed release. |
| 6.2.3 | 6.2.3.15 | Migrate to a fixed release. |
| 6.3.0 | 6.3.0.5 (late October 2019) |
6.4.0.4 |
| 6.4.0 | 6.4.0.4 | 6.4.0.4 |
| 6.5.0 | Not vulnerable. |
Not vulnerable. |
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 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 |
|---|---|---|---|---|
| 1.2 | Updated ASA Fixed Release table. | Fixed Software | Final | 2019-November-14 |
| 1.1 | Updated FTD Fixed Release table. | Fixed Software | Final | 2019-October-18 |
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