Summary

• A vulnerability in the implementation of Security Assertion Markup Language (SAML) Single Sign-On (SSO) authentication for Cisco AnyConnect Secure Mobility Client for Desktop Platforms, Cisco Adaptive Security Appliance (ASA) Software, and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to establish an authenticated AnyConnect session through an affected device running ASA or FTD Software. The authentication would need to be done by an unsuspecting third party.
  
  The vulnerability exists because there is no mechanism for the ASA or FTD Software to detect that the authentication request originates from the AnyConnect client directly. An attacker could exploit this vulnerability by persuading a user to click a crafted link and authenticating using the company's Identity Provider (IdP). A successful exploit could allow the attacker to hijack a valid authentication token and use that to establish an authenticated AnyConnect session through an affected device running ASA or FTD Software.
  
  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-20180418-asaanyconnect

Affected Products

• Vulnerable Products

  This vulnerability affects the Cisco AnyConnect Secure Mobility Client, and ASA Software and FTD Software configured for SAML 2.0-based SSO for AnyConnect Remote Access VPN that is running on the following Cisco products:
  

  • 3000 Series Industrial Security Appliances (ISA)
  • ASA 5500 Series Adaptive Security Appliances
  • ASA 5500-X Series Next-Generation Firewalls
  • ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers
  • Adaptive Security Virtual Appliance (ASAv)
  • Firepower 2100 Series Security Appliance
  • Firepower 4100 Series Security Appliance
  • Firepower 9300 ASA Security Module
  • FTD Virtual (FTDv)

  ASA Software

  The ASA Software is only vulnerable if running software version 9.7.1 or later.

  Determining the Cisco ASA Software Release

  To determine whether a vulnerable version of Cisco ASA Software is running on a device, administrators can use the show version command in the CLI. The following example shows the output of the command for a device that is running Cisco ASA Software Release 9.7(1)4:
  

  ciscoasa# show version | include Version
  Cisco Adaptive Security Appliance Software Version 9.7(1)4
  Firepower Extensible Operating System Version 2.1(1.66)
  Baseboard Management Controller (revision 0x1) Firmware Version: 2.4

  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.

  FTD Software

  The FTD Software is only vulnerable if running software version 6.2.1 or later.

  Determining the Cisco FTD Software Release

  To determine which Cisco FTD Software release is running on a device, administrators can log in to the device and use the show version command in the CLI. The following example shows the output of the command for a device that is running Cisco FTD Software Release 6.2.2:

  > show version
  
  ------------------[ ftd ]-----------------------
  Model : Cisco Firepower 2130 Threat Defense (77) Version 6.2.2 (Build 81)
  UUID : 0cd3595a-7efa-11e7-aaa1-ee3989c8bf25
  Rules update version : 2017-12-20-001-vrt
  VDB version : 290
  ----------------------------------------------------

  AnyConnect Software

  The AnyConnect Secure Mobility Client Software is only vulnerable if running software version 4.4.00243 or later.

  ASA and FTD Features

  The ASA software and the FTD software are vulnerable only if all of the following features are configured:

  1. SAML 2.0 Identity Provider (IdP)
  2. SAML 2.0 Service Provider (SP)
  3. AnyConnect Remote Access VPN

  Note: SAML 2.0 for AnyConnect features are first supported as of ASA release 9.7.1, FTD release 6.2.1, and AnyConnect Secure Mobility Client release 4.4.00243.

  To determine whether ASA or FTD is configured with a SAML 2.0 IdP, administrators can use the show webvpn saml idp CLI command. The following output shows an ASA configured with a SAML 2.0 IdP:

  ciscoasa# show webvpn saml idp
   saml idp my_domain_idp
    url sign-in https://asa-dev.my.domain.com/idp/endpoint/HttpRedirect
    url sign-out https://asa-dev.my.domain.com/idp/endpoint/HttpRedirect
    trustpoint idp my_domain_trustpoint
    trustpoint sp asa_trustpoint

  To determine whether ASA or FTD is configured as SAML 2.0 SP, administrators can use the show running-config tunnel-group | include remote-access|webvpn-attributes|saml CLI command. The following output shows an ASA configured as SAML 2.0 SP:

  ciscoasa# show running-config tunnel-group | include remote-access|webvpn-attributes|saml
  tunnel-group cloud_idp_onelogin type remote-access
  tunnel-group cloud_idp_onelogin webvpn-attributes
   authentication saml
   saml identity-provider my_domain_idp

  To determine whether ASA or FTD is configured for AnyConnect Remote Access VPN, administrators can use the show running-config CLI command and consult the following table for vulnerable configurations.

  Feature	Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)	crypto ikev2 enable <interface_name> client-services port <port #> webvpn  anyconnect enable
  AnyConnect IKEv2 Remote Access (without client services)	crypto ikev2 enable <interface_name> webvpn  anyconnect enable
  AnyConnect SSL VPN	webvpn  enable <interface_name>

  Products Confirmed Not Vulnerable

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

Details

• The vulnerability described in this advisory originates from the dilemma that the head-end device that has the SAML 2.0-based SSO for AnyConnect feature enabled has no way to verify that the authentication request came from the same machine that is running the AnyConnect Secure Mobility Client.
  
  The fix for this vulnerability involves changes in both the head-end device's ASA software and the client-side's AnyConnect Secure Mobility Client. This includes embedded browser functionality in the AnyConnect Secure Mobility Client. For a complete fix, both the head-end device and the AnyConnect Secure Mobility Client must be upgraded.
  
  As the fix for this vulnerability requires protocol adjustments, the ASA has no automatic backward compatibility between the behavior of a solution running software versions prior to the fix and the default behavior of solutions running software versions that do include the fix.
  
  For a transition period, both the AnyConnect Secure Mobility Client and ASA Software will support both methods. The AnyConnect Secure Mobility Client will automatically detect the correct behavior when talking to a head-end device. On the ASA side, the previous behavior will be disabled by default. The previous behavior can be enabled manually per Connection Profile ("tunnel-group") using the newly introduced saml external-browser command under webvpn-attributes.
  
  When upgrading an ASA that has the SAML 2.0-based SSO for AnyConnect feature enabled, the new behavior will be enforced after the upgrade. Customers who cannot upgrade their AnyConnect clients at the same time will need to re-enable the previous behavior manually by adding the saml external-browser command after the ASA upgrade has completed. Cisco recommends removing the saml external-browser command after all AnyConnect clients have been migrated.

  Please refer to the Important Notes section in the Release Notes for the Cisco ASA Series, 9.9(x), the About SSO and SAML 2.0 section in the Cisco ASA Series VPN CLI Configuration Guide, 9.9, the AnyConnect 4.6.00362 New Features section in the Release Notes for Cisco AnyConnect Secure Mobility Client, Release 4.6, and the VPN Authentication Using SAML section in the Cisco AnyConnect Secure Mobility Client Administrator Guide, Release 4.6 for further information on the changed behavior.

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

  Customers should upgrade to an appropriate release as indicated in the table(s) in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
  

  • cisco-sa-20180418-asa1: Cisco Adaptive Security Appliance SSL Certificate Bypass Vulnerability
  • cisco-sa-20180418-asa2: Cisco Adaptive Security Appliance Flow Creation Denial of Service Vulnerability
  • cisco-sa-20180418-asa3: Cisco Adaptive Security Appliance TLS Denial of Service Vulnerability
  • cisco-sa-20180418-asaanyconnect: Cisco ASA Software, FTD Software, and AnyConnect Secure Mobility Client SAML Authentication Session Fixation Vulnerability
  • cisco-sa-20180418-asa_inspect: Cisco Adaptive Security Appliance Application Layer Protocol Inspection Denial of Service Vulnerability

  In the following table(s), the left column lists major releases of Cisco software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in this collection of advisories and the current recommended release for those vulnerabilities.

  Note: For a complete fix, both the ASA or FTD Software on the head-end device and the AnyConnect Secure Mobility Client must be upgraded.

  ASA Software

  Cisco ASA Major Release	First Fixed Release for This Vulnerability	Recommended Fixed Release for All the Vulnerabilities Described in this Collection of Advisories
  Prior to 9.11	Not vulnerable2	9.1.7.20
  9.1	Not vulnerable2	9.1.7.20
  9.2	Not vulnerable2	9.2.4.27
  9.31	Not vulnerable2	9.4.4.14
  9.4	Not vulnerable2	9.4.4.14
  9.51	Not vulnerable2	9.6.4.6
  9.6	Not vulnerable2	9.6.4.6
  9.7	9.7.1.24	9.7.1.24
  9.8	9.8.2.28	9.8.2.28
  9.9	9.9.2.1	9.9.2.1

  
  ¹ Cisco ASA Software releases prior to 9.1 and ASA releases 9.3 and 9.5 have reached End of Software Maintenance. Customers should migrate to a supported release.
  ² SAML 2.0 for AnyConnect features are first supported as of software release 9.7.1.

  The software is available for download from the Software Center on Cisco.com by navigating to Products > Security > Firewalls > Adaptive Security Appliances (ASA) > ASA 5500-X Series Firewalls, where there is a list of ASA hardware platforms. The majority of these software releases are listed under Interim.

  FTD Software

  Cisco FTD Major Release	First Fixed Release for This Vulnerability	Recommended Fixed Release for All the Vulnerabilities Described in this Collection of Advisories
  6.0	Not vulnerable1	Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform) Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300)
  6.0.1	Not vulnerable1	Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform) Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300)
  6.1.0	Not vulnerable1	Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform) Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300)
  6.2.0	Not vulnerable1	6.2.0.5
  6.2.1	Migrate to 6.2.2 Hotfix	Cisco_FTD_SSP_Hotfix_BD-6.2.2.3-4.sh.REL.tar (41xx and 9300 FTD hardware platforms) Cisco_FTD_SSP_FP2K_Hotfix_BD-6.2.2.3-4.sh.REL.tar (21xx FTD hardware platform) Cisco_FTD_Hotfix_BD-6.2.2.3-4.sh.REL.tar (All other FTD hardware platforms)
  6.2.2	Cisco_FTD_SSP_Hotfix_BD-6.2.2.3-4.sh.REL.tar (41xx and 9300 FTD hardware platforms) Cisco_FTD_SSP_FP2K_Hotfix_BD-6.2.2.3-4.sh.REL.tar (21xx FTD hardware platform) Cisco_FTD_Hotfix_BD-6.2.2.3-4.sh.REL.tar (All other FTD hardware platforms)	Cisco_FTD_SSP_Hotfix_BD-6.2.2.3-4.sh.REL.tar (41xx and 9300 FTD hardware platforms) Cisco_FTD_SSP_FP2K_Hotfix_BD-6.2.2.3-4.sh.REL.tar (21xx FTD hardware platform) Cisco_FTD_Hotfix_BD-6.2.2.3-4.sh.REL.tar (All other FTD hardware platforms)
  6.2.3	Cisco_FTD_SSP_Hotfix_A-6.2.3.1-10.sh.REL.tar (41xx and 9300 FTD hardware platforms) Cisco_FTD_SSP_FP2K_Hotfix_A-6.2.3.1-10.sh.REL.tar (21xx FTD hardware platform) Cisco_FTD_Hotfix_A-6.2.3.1-10.sh.REL.tar (All other FTD hardware platforms)	Cisco_FTD_SSP_Hotfix_A-6.2.3.1-10.sh.REL.tar (41xx and 9300 FTD hardware platforms) Cisco_FTD_SSP_FP2K_Hotfix_A-6.2.3.1-10.sh.REL.tar (21xx FTD hardware platform) Cisco_FTD_Hotfix_A-6.2.3.1-10.sh.REL.tar (All other FTD hardware platforms)

  
  ¹ Remote Access VPN features are first supported as of software release 6.2.1.

  The software is available for download from the Software Center on Cisco.com by navigating to Products > Security > Firewalls> Next-Generation Firewalls (NGFW), where there is a list of possible FTD hardware platforms.

  AnyConnect Secure Mobility Client

  Cisco AnyConnect Secure Mobility Client Major Release	First Fixed Release for This Vulnerability	Recommended Fixed Release for All the Vulnerabilities Described in this Collection of Advisories
  Prior to 4.41	Not vulnerable	Not applicable2
  4.4	Affected; migrate to 4.6	Not applicable2
  4.5	Affected; migrate to 4.6	Not applicable2
  4.6	Not vulnerable	Not applicable2

  
  ¹ SAML 2.0 SSO features are first supported as of software release 4.4.00243.
  ² This is the only vulnerability of this collection of advisories that affects the Cisco AnyConnect Secure Mobility Client.
  
  The software is available for download from the Software Center on Cisco.com by navigating to Products > Security > VPN and Endpoint Security Clients > Cisco VPN Clients > AnyConnect Secure Mobility Client > AnyConnect Secure Mobility Client v4.x.

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-20180418-asaanyconnect

Revision History

• Version	Description	Section	Status	Date
  1.2	Updated advisory metadata to reflect affected versions documented in Fixed Software section.	—	Final	2018-October-05
  1.1	Added references to ASA and AnyConnect documentation; re-iterated the need to upgrade both ASA/FTD software and the AnyConnect client for a complete fix.	Details, Fixed Releases	Final	2018-April-19
  1.0	Initial public release.	—	Final	2018-April-18

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