Summary

• A vulnerability in the ingress traffic validation of Cisco IOS XE Software for Cisco Aggregation Services Router (ASR) 900 Route Switch Processor 3 (RSP3) could allow an unauthenticated, adjacent attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition.

  The vulnerability exists because the software insufficiently validates ingress traffic on the ASIC used on the RSP3 platform. An attacker could exploit this vulnerability by sending a malformed OSPF version 2 (OSPFv2) message to an affected device. A successful exploit could allow the attacker to cause a reload of the iosd process, triggering a reload of the affected device and resulting in a DoS condition.

  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-20190327-rsp3-ospf

  This advisory is part of the March 27, 2019, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 17 Cisco Security Advisories that describe 19 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2019 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco ASR 900 RSP3 devices that are running Cisco IOS XE Software and are configured for OSPFv2 routing and OSPF Message Digest 5 (MD5) cryptographic authentication.

  Note: Devices configured for OSPFv2 routing and Hashed Message Authentication Code-Secure Hash Algorithm (HMAC-SHA) cryptographic authentication are not affected by this vulnerability.

  For information about which Cisco IOS XE Software releases are vulnerable, see the Fixed Software section of this advisory.

  Determining Whether OSPFv2 Routing Is Configured

  Administrators can use the show running-config | include router ospf command to determine whether OSPFv2 routing is enabled. The following example shows the output of the command for a device that has the OSPFv2 routing feature enabled:

  rsp3#show running-config | include router ospf
  router ospf 1

  Empty output of this command indicates that the feature is not configured.

  Determining Whether OSPF MD5 Authentication Is Configured

  Administrators can use the show running-config | include authentication message-digest command to determine whether OSPF MD5 authentication is enabled on any interface or globally. The following example shows the output of the command from a device that has OSPF MD5 authentication enabled on one interface:

  rsp3-1#show running-config | include authentication message-digest
   ip ospf authentication message-digest

  The following example shows the output of the command from a device that has OSPF MD5 authentication enabled globally for OSPF area 0:

  rsp3-2#show running-config | include authentication message-digest
   area 0 authentication message-digest

  Empty output of this command indicates that the feature is not enabled on any interface or globally.

  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 16.6.1 and has an installed image name of PPC_LINUX_IOSD-UNIVERSALK9-M:

  rsp3-device# show version
  Cisco IOS XE Software, Version 16.06.01
  Cisco IOS Software [Everest], ASR900 Software (PPC_LINUX_IOSD-UNIVERSALK9-M), Version 16.6.1, RELEASE SOFTWARE (fc2)
  Technical Support: http://www.cisco.com/techsupport
  Copyright (c) 1986-2017 by Cisco Systems, Inc.
  Compiled Sat 22-Jul-17 03:12 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.

  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.

Workarounds

• There are no workarounds that address this vulnerability.

  To mitigate this issue on Cisco IOS Software releases 15.4(1)T and later, administrators can configure OSPFv2 to use HMAC-SHA algorithms for cryptographic authentication instead of MD5 algorithms.

  Information about platform support and Cisco software image support is available through Cisco Feature Navigator. Further information on configuring OSPFv2 for cryptographic authentication using HMAC-SHA is available in the OSPFv2 Cryptographic Authentication chapter of the IP Routing: OSPF Configuration Guide.

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 or 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.

  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.

  Note: Starting with Cisco IOS XE Software Release 16.9.1, any upgrade will require Smart Licensing. Customers who plan to upgrade Cisco IOS XE to Release 16.9.1 or later are advised to consider the Smart Licensing requirement. The following documentation provides additional information: Smart Licensing.

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-20190327-rsp3-ospf

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2019-March-27

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