Summary

• Multiple Cisco products are affected by a vulnerability in 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 modified HTTP packets used in chunked responses. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a 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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-bypass-3eCfd24j

Affected Products

• Vulnerable Products

  At the time of publication, this vulnerability affected the following Cisco products if they were running a vulnerable 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 MX Series Security Appliances¹

  1. See Products Confirmed Not Vulnerable section in this advisory for exceptions.

  This vulnerability also affects the open-source Snort project version prior to 2.9.13.1. For more information, see the Snort website.

  For information about which Cisco software releases were vulnerable at the time of publication, 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.

  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 MX64 Security Appliances
  • Meraki MX64W Security Appliances
  • Meraki vMX100 Virtual Appliances
  • Meraki Z1 Appliances
  • Meraki Z3 Series Appliances

Workarounds

• There are no workarounds that address this vulnerability. Please contact TAC for mitigations.

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 FTD Software

  Cisco FTD Software Release	First Fixed Release for This Vulnerability
  6.01	6.3.0.1
  6.0.11	6.3.0.1
  6.1.0	6.3.0.1
  6.2.0	6.3.0.1
  6.2.1	6.3.0.1
  6.2.2	6.3.0.1
  6.2.3	6.3.0.1
  6.3.0	6.3.0.1
  6.4.0	Not vulnerable.
  6.5.0	Not vulnerable.
  6.6.0	Not vulnerable.

  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.

  Cisco UTD Snort IPS Engine Software for IOS XE

  UTD SNORT IPS Engine IOS XE Release	First Fixed Release for This Vulnerability
  16.9	16.9.5
  16.12	16.12.2
  17.1	Not vulnerable.
  17.2	Not vulnerable.

  See the Details section in the bug IDs CSCvq96573 for the most complete and current information.

  Cisco UTD Engine Software for IOS XE SD-WAN

  UTD Engine IOS XE SD-WAN Release	First Fixed Release for This Vulnerability
  16.10	16.10.3b
  16.12	16.12.1d
  17.2	Not vulnerable.

  See the Details section in the bug IDs CSCvq96573 for the most complete and current information.

  Meraki MX Series Security Appliances

  Meraki MX Series Security Appliance Release	First Fixed Release for This Vulnerability
  MX 14	MX 14.53
  MX 15	MX 15.33 (beta)

  Open Source SNORT

  This is fixed in the open-source Snort project version 2.9.13.1 and later. For more information, see the Snort website.

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 by Santosh Krishnamurthy of Cisco during internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-bypass-3eCfd24j

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2020-OCT-21

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