Cisco Adaptive Security Appliance CLI Remote Code Execution Vulnerability

Summary

• A vulnerability in the command-line interface (CLI) parser of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, local attacker to create a denial of service (DoS) condition or potentially execute arbitrary code. An attacker could exploit this vulnerability by invoking certain invalid commands in an 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:
  http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160817-asa-cli

Affected Products

• Vulnerable Products

  Cisco Adaptive Security Appliance (ASA) Software Releases earlier than 8.4(3) are vulnerable. An attacker must have local access and be authenticated to exploit this vulnerability.
  
  Affected Cisco ASA Software running on the following products may be affected by this vulnerability:
  

  • Cisco ASA 5500 Series Adaptive Security Appliances
  • Cisco ASA 5500-X Series Next-Generation Firewalls
  • Cisco PIX Firewalls*
  • Cisco Firewall Services Module (FWSM)*

  Refer to the "Fixed Software" section for additional information about fixed releases.
  
  * Note: Cisco Firewall Service Modules and Cisco PIX Firewalls have passed the last day of software support milestone as stated in the published End of Life (EoL) documents. Further investigations into these devices will not be performed, and fixed software will not be made available. Please see the following EoL documents for further information:
  

  • Cisco Firewall Services Module (FWSM)
    http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/catalyst-6500-series-firewall-services-module/eol_c51-699134.html
  • Cisco PIX Firewalls
    http://www.cisco.com/c/en/us/products/security/pix-500-series-security-appliances/eos-eol-notice-listing.html

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by this vulnerability.

Workarounds

• There are no workarounds that address this vulnerability.
  
  An attacker must be authenticated to trigger this vulnerability. Given their role in a customer’s infrastructure, networking devices are a valuable target for threat actors and should be protected as such. Cisco recommends that customers of all networking vendors include in their operational procedures methods for preventing and detecting compromise. Please refer to the Cisco Guide to Harden Cisco ASA Firewall, which contains information to help secure Cisco ASA devices and increase the overall security of the network.

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

  The following table indicates the earliest software releases that include fixes for this vulnerability:

  Cisco ASA Major Release	First Fixed Release
  7.2	Affected, migrate to 8.4(3) or later
  8.0	Affected, migrate to 8.4(3) or later
  8.1	Affected, migrate to 8.4(3) or later
  8.2	Affected, migrate to 8.4(3) or later
  8.3	Affected, migrate to 8.4(3) or later
  8.4	8.4(3)
  8.5	Affected, migrate to 9.0(1) or later
  8.6	Affected, migrate to 9.0(1) or later
  8.7	Affected, migrate to 9.0(1) or later
  9.0	9.0(1)
  9.1	Not affected
  9.2	Not affected
  9.3	Not affected
  9.4	Not affected
  9.5	Not affected
  9.6	Not affected

  Cisco ASA Major Release	7.2
  First Fixed Release	Affected, migrate to 8.4(3) or later
  Cisco ASA Major Release	8.0
  First Fixed Release	Affected, migrate to 8.4(3) or later
  Cisco ASA Major Release	8.1
  First Fixed Release	Affected, migrate to 8.4(3) or later
  Cisco ASA Major Release	8.2
  First Fixed Release	Affected, migrate to 8.4(3) or later
  Cisco ASA Major Release	8.3
  First Fixed Release	Affected, migrate to 8.4(3) or later
  Cisco ASA Major Release	8.4
  First Fixed Release	8.4(3)
  Cisco ASA Major Release	8.5
  First Fixed Release	Affected, migrate to 9.0(1) or later
  Cisco ASA Major Release	8.6
  First Fixed Release	Affected, migrate to 9.0(1) or later
  Cisco ASA Major Release	8.7
  First Fixed Release	Affected, migrate to 9.0(1) or later
  Cisco ASA Major Release	9.0
  First Fixed Release	9.0(1)
  Cisco ASA Major Release	9.1
  First Fixed Release	Not affected
  Cisco ASA Major Release	9.2
  First Fixed Release	Not affected
  Cisco ASA Major Release	9.3
  First Fixed Release	Not affected
  Cisco ASA Major Release	9.4
  First Fixed Release	Not affected
  Cisco ASA Major Release	9.5
  First Fixed Release	Not affected
  Cisco ASA Major Release	9.6
  First Fixed Release	Not affected

  
  

Exploitation and Public Announcements

• On August 15, 2016, Cisco was alerted to information posted online by the Shadow Brokers group, which claimed to possess disclosures from the Equation Group. The posted materials included exploits for firewall products from multiple vendors. The Cisco products mentioned were the PIX and ASA firewalls.

Source

• The exploit of this vulnerability was publicly disclosed by the alleged Shadow Brokers group.

URL

• http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160817-asa-cli

Revision History

• Version	Description	Section	Status	Date
  1.1	Clarified first fixed software version, added table of affected software.	Affected Products, Fixed Software	Final	2016-August-18
  1.0	Initial public release.	-	Final	2016-August-17

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