Summary

• Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass the configured file policies on an affected system.

  The vulnerability is due to errors in how the Snort detection engine handles specific HTTP responses. An attacker could exploit this vulnerability by sending crafted HTTP packets that would flow through an affected system. A successful exploit could allow the attacker to bypass the configured file policies and deliver a malicious payload to the protected network.

  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-snort_filepolbypass-m4X5DgOP

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)¹
  • 3000 Series Industrial Security Appliances (ISAs)
  • 4000 Series Integrated Services Routers (ISRs)
  • Cloud Services Router 1000V Series
  • Firepower Threat Defense (FTD) Software
  • Integrated Services Virtual Router (ISRv)¹

  1. This vulnerability affected these products only if they were running a Cisco IOS XE SD-WAN Software image.

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  This vulnerability also affected all open source Snort project releases earlier than Release 2.9.16. For more information, see the Snort website.

  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 MX Security Appliances

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 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.

  Fixed Releases

  Cisco FTD Software

  At the time of publication, Cisco FTD Software releases 6.6.0 and later contained the fix for this vulnerability.¹

  See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

  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:

  • 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 Cisco IOS XE Software

  At the time of publication, Cisco Unified Threat Defense (UTD) Snort Intrusion Protection System (IPS) Engine Software for Cisco IOS XE Software releases 17.2.1r and later contained the fix for the CSCvt10151 portion of this vulnerability.

  At the time of publication, Cisco had not released updates that address the CSCvt28138 portion of this vulnerability for Cisco Unified Threat Defense (UTD) Snort Intrusion Protection System (IPS) Engine Software for Cisco IOS XE Software.

  See the Details section in the bug IDs CSCvt10151 and CSCvt28138 for the most complete and current information.

  Cisco UTD Snort IPS Engine Software for Cisco IOS XE SD-WAN Software

  At the time of publication, Cisco had not released updates that address this vulnerability for Cisco UTD Snort IPS Engine Software for Cisco IOS XE SD-WAN Software.

  See the Details section in the bug IDs CSCvt10151 and CSCvt28138 for the most complete and current information.

  Open Source Snort

  At the time of publication, open source Snort project releases 2.9.16 and later contained the fix for this vulnerability. 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-snort_filepolbypass-m4X5DgOP

Revision History

• Version	Description	Section	Status	Date
  1.1	Added fixed release information for Cisco UTD Snort IPS Engine for Cisco IOS XE Software.	Fixed Release	Final	2020-MAY-08
  1.0	Initial public release.	—	Final	2020-MAY-06

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