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Cisco Security Advisory

Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software FTP Inspection Bypass Vulnerability

Medium
Advisory ID:
cisco-sa-asaftd-ftpbypass-HY3UTxYu
First Published:
2020 October 21 16:00 GMT
Last Updated:
2020 October 23 01:07 GMT
Version 2.0:
Final
Workarounds:
No workarounds available
Cisco Bug IDs:
CSCvt13445
CVE-2020-3564
CWE-284
CVSS Score:
Base 5.8Click Icon to Copy Verbose Score
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
CVE-2020-3564
CWE-284

Summary

  • Update from October 22nd, 2020: Cisco has become aware of a new Cisco Adaptive Security Appliance vulnerability that could affect the fixed releases recommended for code trains 9.13 and 9.14 in the Fixed Software section of this advisory. See the Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability for additional information.

    A vulnerability in the FTP inspection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass FTP inspection.

    The vulnerability is due to ineffective flow tracking of FTP traffic. An attacker could exploit this vulnerability by sending crafted FTP traffic through an affected device. A successful exploit could allow the attacker to bypass FTP inspection and successfully complete FTP connections.

    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-asaftd-ftpbypass-HY3UTxYu

Affected Products

  • Vulnerable Products

    At the time of publication, this vulnerability affected devices if they were running a vulnerable release of Cisco ASA Software or FTD Software and had strict FTP inspection enabled.

    For information about which Cisco software releases were 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.

    Determine Whether FTP Inspection Is Enabled on an ASA

    To determine whether FTP inspection is enabled on an ASA, use the show running-config policy-map command and then the show running-config service-policy command.

    Use the show running-config policy-map command and check whether the inspect ftp strict command is present in at least one policy map. In the following output, the global-policy policy map includes the inspect ftp strict 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 strict 
  inspect h323 h225

    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 strict command is applied globally or to an interface, strict FTP inspection is enabled.

    Determine Whether FTP Inspection Is Enabled on FTD

    Configuring inspect ftp strict on FTD requires the use of FlexConfig. To determine if inspect ftp strict is enabled on an FTD device, Secure Shell (SSH) to the management interface of the device and use the process previously outlined for the ASA.

    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 Firepower Management Center (FMC) Software.

Workarounds

  • There are no workarounds that address this vulnerability.

Fixed Software

  • 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, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

    The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability described in this advisory and which release included the fix for this vulnerability.

    Cisco ASA Software

    Cisco ASA Software Release First Fixed Release for This Vulnerability
    Earlier than 9.61 Migrate to a fixed release.
    9.61 Migrate to a fixed release.
    9.71 Migrate to a fixed release.
    9.8 9.8.4.26
    9.9 9.9.2.80
    9.10 9.10.1.44
    9.12 9.12.4.2
    9.13 9.13.1.13
    9.14 9.14.1.19

    1. Cisco ASA Software releases 9.7 and earlier have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.

    Cisco FTD Software

    Cisco FTD Software Release First Fixed Release for This Vulnerability
    Earlier than 6.2.21 Migrate to a fixed release.
    6.2.2 Migrate to a fixed release.
    6.2.3 Migrate to a fixed release.
    6.3.0 6.3.0.6 (future release)
    6.4.0 6.4.0.10
    6.5.0 6.5.0.5 (future release)
    6.6.0 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.

Exploitation and Public Announcements

  • 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

  • This vulnerability was found during internal security testing.

Cisco Security Vulnerability Policy

  • 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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Revision History

  • Version Description Section Status Date
    2.0 Updated the Summary section to provide information on a new vulnerability affecting fixed release recommendations for code trains 9.13 and 9.14. Summary Final 2020-OCT-22
    1.0 Initial public release. - Final 2020-OCT-21
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Cisco Security Vulnerability Policy

  • 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

Related to This Advisory