Summary

• A vulnerability in the Internet Key Exchange Version 1 (IKEv1) XAUTH code of Cisco ASA Software could allow an authenticated, remote attacker to cause a reload of an affected system.
  
  The vulnerability is due to insufficient validation of the IKEv1 XAUTH parameters passed during an IKEv1 negotiation. An attacker could exploit this vulnerability by sending crafted parameters.
  
  Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability only affects systems configured in routed firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 or IPv6 traffic. A valid IKEv1 Phase 1 needs to be established to exploit this vulnerability, which means that an attacker would need to have knowledge of a pre-shared key or have a valid certificate for phase 1 authentication.
  
  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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170419-asa-xauth

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco ASA Software running on the following products:
  

  • Cisco ASA 1000V Cloud Firewall
  • Cisco ASA 5500 Series Adaptive Security Appliances
  • Cisco ASA 5500-X Series Next-Generation Firewalls
  • Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers
  • Cisco Adaptive Security Virtual Appliance (ASAv)
  • Cisco ASA for Firepower 9300 Series
  • Cisco ISA 3000 Industrial Security Appliance

  Refer to the “Fixed Software” section of this security advisory for more information about affected releases.
  
  Cisco ASA Software is affected by this vulnerability if the system is configured to terminate remote access IKEv1 VPN connections using IPsec client and XAUTH is used for user authentication.
  
  Cisco ASA Software is not affected by this vulnerability if the system is configured to terminate the following VPN connections:
  

  • Clientless SSL
  • AnyConnect SSL
  • Internet Key Exchange Version 2 (IKEv2) AnyConnect
  • LAN-to-LAN VPN
  • Layer 2 Tunneling Protocol (L2TP)-IPsec VPN

  To determine whether a Cisco ASA Software appliance is configured to terminate IKEv1 remote access VPN connections, a dynamic crypto map must be configured for at least one interface. Administrators should use the show running-config crypto map | include interface|dynamic command and verify that the output includes a dynamic crypto map. The following example shows a crypto map named outside_map configured on the outside interface:
  

  ciscoasa# show running-config crypto map | include interface|dynamic
  
  crypto map outside_map 65535 ipsec-isakmp dynamic mydynamic
  crypto map outside_map interface outside

  By default, remote access VPN using IPsec VPN clients use XAUTH for user authentication. Administrators can verify whether the VPN client is using XAUTH by using the show running-config all tunnel-group <tg_name> ipsec-attributes | include xauth command and verifying that ikev1 user-authentication xauth is present. The following example shows a Cisco ASA Software appliance with a tunnel-group named RAVPN and with XAUTH configured:
  

  ciscoasa# show  running-config all tunnel-group RAVPN ipsec-attributes | include xauth
  
  [...]
  ikev1 user-authentication xauth

  Note: Remote access VPN using an IPsec client is not configured by default; however, when configured, the XAUTH feature will be enabled.
  
  Determining the Running Software Release
  
  To determine whether a vulnerable release of Cisco ASA Software is running on an appliance, administrators can use the show version command. The following example shows the results of the show version command on an appliance running Cisco ASA Software Release 9.2(1):
  

  ciscoasa# show version | include Version
  
  Cisco Adaptive Security Appliance Software Version 9.2(1) 
  Device Manager Version 7.4(1)

  Customers who use Cisco Adaptive Security Device Manager (ASDM) to manage devices can locate the software release in the table that appears in the login window or the upper-left corner of the Cisco ASDM window.

  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

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:
  http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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:
  http://www.cisco.com/en/US/support/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 major releases of Cisco ASA Software. The right column indicates whether a major release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability.

  Cisco ASA Software Major Release	First Fixed Release
  Prior to 9.01	Affected, migrate to 9.1(7.7) or later
  9.01	Affected, migrate to 9.1(7.7) or later
  9.1	9.1(7.7) or later
  9.2	9.2(4.11) or later
  9.31	Affected, migrate to 9.4(4) or later
  9.4	9.4(4) or later
  9.5	9.5(3) or later
  9.6	9.6(1.5) or later
  9.7	Not affected
  9.8	Not affected

  
  ¹ Cisco ASA Software releases prior to 9.1 and Cisco ASA Software Release 9.3 have reached end-of-software maintenance. Customers should migrate to a supported release.
  
  Note: It is possible that certain fixed software releases for this vulnerability are affected by a bug described in Cisco Field Notice FN-64291 where a security appliance may fail to pass traffic after 213 days of uptime. Customers should review this notice before determining a course of action for addressing the vulnerability described in this advisory. The issue described in the Cisco Field Notice is not a security vulnerability.

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 support cases.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170419-asa-xauth

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2017-April-19

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