Summary

• A vulnerability in the Server Message Block Version 2 (SMBv2) and Version 3 (SMBv3) protocol implementation for the Cisco Firepower System Software could allow an unauthenticated, remote attacker to cause the device to run low on system memory, possibly preventing the device from forwarding traffic. It is also possible that a manual reload of the device may be required to clear the condition.

  The vulnerability is due to incorrect SMB header validation. An attacker could exploit this vulnerability by sending a custom SMB file transfer through the targeted device. A successful exploit could cause the device to consume an excessive amount of system memory and prevent the SNORT process from forwarding network traffic. This vulnerability can be exploited using either IPv4 or IPv6 in combination with SMBv2 or SMBv3 network traffic.

  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-20181003-fp-smb-snort

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco Firepower System Software running on any of the following Cisco products:

  • Adaptive Security Appliance (ASA) 5500-X Series with FirePOWER Services
  • Adaptive Security Appliance (ASA) 5500-X Series Next-Generation Firewalls
  • Advanced Malware Protection (AMP) for Networks, 7000 Series Appliances
  • Advanced Malware Protection (AMP) for Networks, 8000 Series Appliances
  • Firepower 2100 Series Security Appliances
  • Firepower 4100 Series Security Appliances
  • FirePOWER 7000 Series Appliances
  • FirePOWER 8000 Series Appliances
  • Firepower 9300 Series Security Appliances
  • FirePOWER Threat Defense for Integrated Services Routers (ISRs)
  • Firepower Threat Defense Virtual
  • Industrial Ethernet 3000 Series Switches
  • Next-Generation Intrusion Prevention System (NGIPSv)
  • Virtual Next-Generation Intrusion Prevention System (NGIPSv)

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

  Determine the Cisco Firepower System Software Release

  To determine which Cisco Firepower System Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and refer to the output of the command. The following example shows the output of the command for a device that is running Cisco Firepower System Software Release 6.2.0:

  > show version
  
  ---------------------[ ftd ]---------------------
  Model : Cisco ASA5525-X Threat Defense (75) Version 6.2.0 (Build 362)
  UUID : 2849ba3c-ecb8-11e6-98ca-b9fc2975893c
  Rules update version : 2017-03-15-001-vrt
  VDB version : 279
  ----------------------------------------------------

  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
  • Meraki MX Security Appliances

Indicators of Compromise

• During an active exploitation of this vulnerability, it is possible that the SNORT process could be in Disk Sleep (or in D state) as observed by the operating system command top:

  top - 2017-03-20 13:34:36 up 16 days, 11:57, 0 users, load average: 1.40, 0.76
  Tasks: 100 total, 1 running, 99 sleeping, 0 stopped, 0 zombie
  Cpu(s): 6.4%us, 3.9%sy, 0.0%ni, 54.8%id, 34.0%wa, 0.0%hi, 0.0%si, 0.9%st
  Mem: 3303936k total, 3181128k used, 122808k free, 16944k buffers
  Swap: 3310920k total, 1346860k used, 1964060k free, 207644k cached
  PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
  21732 sfsnort 1 -19 2148m 1.1g 25m D 17 33.9 309:16.55 snort
  21733 sfsnort 1 -19 2154m 1.1g 26m D 8 34.4 337:19.92 snort

  SNORT instances in the D state are hung and cannot be recovered. These unrecoverable instances could prevent traffic from passing through the device, and could indicate that the vulnerability is being exploited on the device. Please contact the Cisco Technical Assistance Center (TAC) if additional assistance is required to determine whether the device has been compromised by this vulnerability.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• 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 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.

  Fixed Releases
  
  In the following table, the left column lists releases of Cisco software. The right 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.
  
  

  Cisco Firepower System Software	First Fixed Release for This Vulnerability
  6.0	6.1.0.7
  6.0.1	6.1.0.7
  6.1.0	6.1.0.7
  6.2.0	6.2.0.5
  6.2.1	6.2.2.3
  6.2.2	6.2.2.3
  6.2.3	Not vulnerable

  To upgrade to a fixed release of Cisco Firepower System 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 and, after installation is complete, reapply the access control policy. The Snort version that is installed depends on the FMC release.
  • For devices that are managed by using Cisco Adaptive Security Device Manager (ASDM) or Cisco Firepower Device Manager (FDM), use the ASDM or FDM interface to install the upgrade and, 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 the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20181003-fp-smb-snort

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2018-October-03

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