Summary

• A vulnerability in the Extensible Authentication Protocol-Transport Layer Security (EAP-TLS) certificate validation during EAP authentication for the Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the ISE application server to restart unexpectedly, causing a denial of service (DoS) condition on an affected system.
  
  The vulnerability is due to incomplete input validation of the client EAP-TLS certificate. An attacker could exploit this vulnerability by initiating EAP authentication over TLS to the ISE with a crafted EAP-TLS certificate. A successful exploit could allow the attacker to restart the ISE application server, resulting in a DoS condition on the affected system. The ISE application could continue to restart while the client attempts to establish the EAP authentication connection.
  
  If an attacker attempted to import the same EAP-TLS certificate to the ISE trust store, it could trigger a DoS condition on the affected system. This exploit vector would require the attacker to have valid administrator credentials.
  
  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-20180516-iseeap

Affected Products

• Vulnerable Products

  The vulnerability affects the following Cisco ISE products:
  

  • Cisco ISE
  • Cisco ISE Express
  • Cisco ISE Virtual Appliance

  To determine which release of the software is currently running on a device, administrators may use the show version command in the device CLI or navigate to the top-right corner and click Settings (gear icon) > About Identity Service Engine in the Admin portal. The output of the command in the CLI is similar to the following example:
  

  ServiceEngine115/admin# show version 

  Cisco Application Deployment Engine OS Release: 2.3
  ADE-OS Build Version: 2.3.0.187
  ADE-OS System Architecture: x86_64
  
  Copyright (c) 2005-2014 by Cisco Systems, Inc.
  All rights reserved.
  Hostname: ServiceEngine115
  
  Version information of installed applications
  ---------------------------------------------
  
  Cisco Identity Services Engine
  ---------------------------------------------
  Version      : 2.0.0.306
  Build Date   : Thu Oct  8 13:25:23 2015
  Install Date : Tue Nov 17 21:02:22 2015     
  
  Cisco Identity Services Engine Patch 
  ---------------------------------------------
  Version      : 5
  Install Date : Fri Jul 07 01:57:01 2017

  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 Cisco ISE Passive Identity Connector.

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

  Cisco Identity Services Engine Release	First Fixed Release for This Vulnerability
  Prior to 1.4.0	Vulnerable; migrate to 1.4.0.253-Patch12
  1.4.0	1.4.0.253-Patch12
  2.0.0	Vulnerable; migrate to 2.1.0.474-Patch7
  2.0.1	Vulnerable; migrate to 2.1.0.474-Patch7
  2.1.0	2.1.0.474-Patch7
  2.2.0	2.2.0.470-Patch5
  2.3.0	Not vulnerable

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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180516-iseeap

Revision History

• Version	Description	Section	Status	Date
  1.2	Metadata update.	—	Final	2018-September-24
  1.1	Updated the fixed release information for Releases 2.0.0, 2.0.1, and 2.1.0.	Fixed Software	Final	2018-June-07
  1.0	Initial public release.	—	Final	2018-May-16

  Show Less