Summary

• A vulnerability in the IPsec driver code of multiple Cisco IOS XE Software platforms and the Cisco ASA 5500-X Series Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to cause the device to reload.

  The vulnerability is due to improper processing of malformed IPsec Authentication Header (AH) or Encapsulating Security Payload (ESP) packets. An attacker could exploit this vulnerability by sending malformed IPsec packets to be processed by an affected device. An exploit could allow the attacker to cause a reload of the 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:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180926-ipsec

  This advisory is part of the September 26, 2018, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 12 Cisco Security Advisories that describe 13 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: September 2018 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Affected Products

• This vulnerability affects multiple platforms running Cisco IOS XE Software and certain Cisco 5500-X Series Adaptive Security Appliances (ASA) running either Cisco ASA Software or Cisco Firepower Threat Defense (FTD) Software. See the following sections for details:

  • Cisco IOS XE Software
  • Cisco ASA Software and Cisco ASA 5500-X Series with Firepower Threat Defense Software

  Vulnerable Products

  Cisco IOS XE Software

  This vulnerability affects Cisco IOS XE Software running on the following products. No other models are affected.

  • Cisco ASR 1000 Series Aggregation Services Routers:
    • ASR 1001-X
    • ASR 1001-HX
    • ASR 1002-X
    • ASR 1002-HX
    • Cisco ASR 1000 Series 100-Gbps Embedded Service Processor (ASR1000-ESP100)
    • Cisco ASR 1000 Series 200-Gbps Embedded Service Processor (ASR1000-ESP200)

  • Cisco 4000 Series Integrated Services Routers:
    • ISR 4431
    • ISR 4451-X

  Cisco IOS XE Software is affected by this vulnerability if the system is configured to terminate IPsec VPN connections. This includes the following:

  • LAN-to-LAN VPN
  • Remote-access VPN, excluding SSL VPN
  • Dynamic Multipoint VPN (DMVPN) 
  • FlexVPN
  • Group Encrypted Transport VPN (GET VPN)
  • IPsec virtual tunnel interfaces (VTIs)
  • Open Shortest Path First Version 3 (OSPFv3) Authentication Support with IPsec

  If a device that is running Cisco IOS XE Software is configured to terminate IPsec VPN connections, either a crypto map must be configured for at least one interface or the device must be configured with IPsec VTIs.

  Administrators should use the show running-config command and verify that the returned output contains a crypto map configured under at least one active interface. The following example shows a crypto map named map-group1 configured on the GigabitEthernet 0/0/0 interface:

  Router# show running-config
  <!-- Output Omitted -->
  interface GigabitEthernet0/0/0
   crypto map map-group1

  Administrators should use the show running-config command and verify that the returned output contains tunnel protection ipsec profile configured under at least one tunnel interface. The following example shows a VTI interface:

  Router# show running-config
  interface tunnel 0
  tunnel mode ipsec ipv4
  tunnel protection ipsec profile PROF1

  Note: IPsec VPN is not configured by default.

  If a device that is running Cisco IOS XE Software is configured to support OSPFv3 Authentication Support with IPsec, the running configuration contains one of the following:

  • ipv6 ospf encryption
  • ipv6 ospf authentication
  • ospfv3 authentication ipsec
  • ospfv3 encryption ipsec
  • area <area-id> authentication ipsec
  • area <area-id> encryption ipsec
  • area <area-id> virtual-link <router-id> authentication ipsec spi
  • area <area-id> virtual-link <router-id> encryption ipsec spi

  The following example shows a device configured for OSPFv3 Authentication Support with IPsec:

  Router# show running-config
  interface GigabitEthernet0/1
  ospfv3 authentication ipsec spi 256 md5 01020304050607080910010203040506 

  Determining the Cisco IOS XE Software Release

  To determine which Cisco IOS XE Software release is running on a device, administrators can log in to the device, use the show version command in the CLI, and then refer to the system banner that appears. If the device is running Cisco IOS XE Software, the system banner displays Cisco IOS Software, Cisco IOS XE Software, or similar text.

  The following example shows the output of the command for a device that is running Cisco IOS XE Software Release 16.2.1 and has an installed image name of CAT3K_CAA-UNIVERSALK9-M:

  ios-xe-device# show version
  
  Cisco IOS Software, Catalyst L3 Switch Software (CAT3K_CAA-UNIVERSALK9-M), Version Denali 16.2.1, RELEASE SOFTWARE (fc1)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2016 by Cisco Systems, Inc.
  Compiled Sun 27-Mar-16 21:47 by mcpre
  .
  .
  .

  For information about the naming and numbering conventions for Cisco IOS XE Software releases, see the Cisco IOS and NX-OS Software Reference Guide.

  Cisco ASA Software and Cisco ASA 5500-X Series with Firepower Threat Defense Software

  This vulnerability affects Cisco ASA Software or Cisco FTD Software running on the following products. No other models are affected.

  Cisco ASA 5500-X Series Adaptive Security Appliances:

  • ASA 5506-X Series
  • ASA 5508-X Series
  • ASA 5516-X Series

  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 IPsec VPN connections. This includes the following:

  • LAN-to-LAN IPsec VPN
  • Remote-access VPN using the IPsec VPN client
  • Layer 2 Tunneling Protocol (L2TP)-over-IPsec VPN connections

  Cisco FTD Software is affected by this vulnerability if the system is configured to terminate IPsec VPN connections. This includes the following:

  • Site-to-site IPsec VPN
  • Remote-access VPN using the IPsec VPN client

  Cisco ASA Software or Cisco FTD Software is not affected by this vulnerability if the system is configured to terminate only the following VPN connections:

  • Clientless SSL 
  • AnyConnect SSL

  If an appliance running Cisco ASA Software is configured to terminate IPsec VPN connections, a crypto map must be configured for at least one interface. Administrators should use the show running-config crypto map | include interface command and verify that it returns output. The following example shows a crypto map named outside_map configured on the outside interface:

  ciscoasa# show running-config crypto map | include interface
  crypto map outside_map interface outside

  Note: IPsec VPN is not configured by default.

  To determine whether an appliance that is running Cisco FTD is configured with site-to-site VPN connections or remote-access VPN connections that use the IPsec VPN client, administrators should use the show running-config command. In the following table, the left column lists the vulnerable Cisco FTD features. The right column indicates the vulnerable configuration from the show running-config command.

  Cisco FTD Feature	Vulnerable Configuration
  AnyConnect IKEv2 Remote Access (with client services)1,2	crypto ikev2 enable <interface_name> client-services port <port #> webvpn   anyconnect enable
  AnyConnect IKEv2 Remote Access (without client services)1,2	crypto ikev2 enable <interface_name> webvpn   anyconnect enable
  Site-to-site VPN connections3	crypto map <crypto_map_name> interface <interface_name>

  ¹ Remote-access VPN features are enabled via Devices > VPN > Remote Access in the Cisco FMC or via Device > Remote Access VPN in Cisco Firepower Device Manager (FDM).
  ² Remote-access VPN features are first supported as of Cisco FTD Software Release 6.2.2.
  ³ Site-to-site VPN features are first supported as of Cisco FTD Software Release 6.2.0.

  Determining the Cisco ASA 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)

  Determining the Cisco FTD Software Release

  Administrators can use the show version command in the CLI to determine the Cisco FTD Software release. In this example, the device is running Release 6.2.2:

  > show version
  ---------------------[ ftd ]---------------------
  Model : Cisco ASA5525-X Threat Defense (75) Version 6.2.2 (Build 362)
  UUID : 2849ba3c-ecb8-11e6-98ca-b9fc2975893c
  Rules update version : 2017-03-15-001-vrt
  VDB version : 279
  ----------------------------------------------------

  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

  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 IOS Software, Cisco IOS XR Software, or Cisco NX-OS Software.

Details

• For this vulnerability to be exploited, the IPsec security associations (SAs) must first be established. 

  An attacker can exploit this vulnerability by using a crafted ESP or AH packet that meets several other conditions, such as matching the IPsec SA SPI and being within the correct sequence window.

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.

  Cisco IOS and IOS XE Software

  To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides a tool, the Cisco IOS Software Checker, that identifies any Cisco Security Advisories that impact a specific software release and the earliest release that fixes the vulnerabilities described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities described in all the advisories identified (“Combined First Fixed”).

  Customers can use this tool to perform the following tasks:

  • Initiate a search by choosing one or more releases from a drop-down list or uploading a file from a local system for the tool to parse
  • Enter the output of the show version command for the tool to parse
  • Create a custom search by including all previously published Cisco Security Advisories, a specific advisory, or all advisories in the most recent bundled publication

  To determine whether a release is affected by any published Cisco Security Advisory, use the Cisco IOS Software Checker on Cisco.com or enter a Cisco IOS Software or Cisco IOS XE Software release—for example, 15.1(4)M2 or 3.13.8S—in the following field:

  By default, the Cisco IOS Software Checker includes results only for vulnerabilities that have a Critical or High Security Impact Rating (SIR). To include results for Medium SIR vulnerabilities, use the Cisco IOS Software Checker on Cisco.com and check the Medium check box in the Impact Rating drop-down list.

  Note: Shortly after the initial publication of this advisory, Cisco determined Cisco IOS XE Software Release 16.8.1 addresses this vulnerability for malformed IPsec Authentication Header (AH) and Encapsulating Security Payload (ESP) packets on Cisco ISR platforms, but only malformed IPsec ESP packets on ASR platforms. Cisco IOS XE Software Release 16.8.1 does not address this vulnerability for malformed IPsec AH packets on ASR platforms. For ASR platforms, Cisco IOS XE Release 16.8.2 is the first fixed release from the Cisco IOS XE Software Release 16.8 train. Because the Cisco IOS Software Checker doesn’t factor platform, it will incorrectly report that Release 16.8.1 is vulnerable.

  For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to the Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, or Cisco IOS XE 3SG Release Notes, depending on the Cisco IOS XE Software release.

  Cisco ASA Software

  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. Customers should upgrade to an appropriate release as indicated in this section.

  Cisco ASA Major Release	First Fixed Release for This Vulnerability
  9.31	Affected; migrate to Release 9.4
  9.4	9.4.4.18
  9.51	Affected; migrate to Release 9.6
  9.6	9.6.4.8
  9.7	Affected; migrate to Release 9.8
  9.8	9.8.2.26
  9.9	9.9.2.2

  ¹ Cisco ASA Software Releases 9.3 and 9.5 have reached end-of-software-maintenance status. Customers should migrate to a supported release.

  Customers can download the software from the Software Center on Cisco.com by clicking Browse all and navigating to Security > Firewalls > Adaptive Security Appliances (ASA) > ASA 5500-X Series Firewalls, where there is a list of ASA hardware platforms.

  Cisco FTD Software

  In the following table, the left column lists major releases of Cisco FTD 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. Customers should upgrade to an appropriate release as indicated in this section.

  Cisco FTD Software Release	First Fixed Release for This Vulnerability
  6.2.0	Affected; migrate to Release 6.2.2.3 or 6.2.3.1 or later.
  6.2.1	Affected; migrate to Release 6.2.2.3 or 6.2.3.1 or later.
  6.2.2	6.2.2.3
  6.2.3	6.2.3.1

  Customers can download the software from the Software Center on Cisco.com by clicking Browse all and navigating to Security > Firewalls > Next-Generation Firewalls (NGFW), where there is a list of Cisco FTD hardware platforms.

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-20180926-ipsec

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated associated data in the Cisco IOS Software Checker to resolve an issue indicating that Cisco IOS XE Release 16.8.1 is not vulnerable. See the Fixed Software Section for details.	Metadata and Fixed Software	Final	2018-September-28
  1.0	Initial public release.	—	Final	2018-September-26

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