Summary

• A vulnerability in the Border Gateway Protocol (BGP) implementation of Cisco NX-OS System Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the device unexpectedly reloading.
  
  The vulnerability is due to incomplete input validation of the BGP update messages. An attacker could exploit this vulnerability by sending a crafted BGP update message to the targeted device. An exploit could allow the attacker to cause the switch to reload unexpectedly. 
  
  The Cisco implementation of the BGP protocol only accepts incoming BGP traffic from explicitly defined peers. To exploit this vulnerability, an attacker must be able to send the malicious packets over a TCP connection that appears to come from a trusted BGP peer, or inject malformed messages into the victim's BGP network. This would require obtaining information about the BGP peers in the affected system's trusted network.
  
  The vulnerability may be triggered when the router receives a malformed BGP message from a peer on an existing BGP session. At least one BGP neighbor session must be established for a router to be vulnerable.
  
  If all BGP peers to the NX-OS Software are Cisco IOS, IOS-XE, or IOS-XR devices and those devices are not configured for Cisco Multicast VPN (MVPN) interautonomous system support, this vulnerability cannot be remotely exploited.
  
  Cisco has released software updates that address this vulnerability. Workarounds that address this vulnerability are not available.
  
  This advisory is available at the following link:
  
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161005-bgp

Affected Products

• Vulnerable Products

  The following Cisco products are affected by this vulnerability when configured with BGP:

  • Nexus 1000v Series Switches
  • Nexus 2000 Series Fabric Extenders
  • Nexus 3000 Series Switches
  • Nexus 3500 Platform Switches
  • Nexus 5000 Series Switches
  • Nexus 5500 Platform Switches
  • Nexus 5600 Platform Switches
  • Nexus 6000 Series Switches
  • Nexus 7000 Series Switches
  • Nexus 7700 Series Switches
  • Nexus 9000 Series Switches in ACI mode
  • Nexus 9000 Series Switches in NX-OS mode

  The vulnerability affects only NX-OS devices configured with BGP functionality and, in addition, the device needs to have at least one BGP neighbor (peer) configured. The potentially malicious BGP peer needs to be configured on the NX-OS device as a BGP neighbor. This vulnerability applies to BGP traffic destined for the device. The device processes BGP packets on TCP port 179 on either IP version 4 (IPv4) or IP version 6 (IPv6).
  
  To determine whether a Nexus device is configured with the BGP feature and a BGP neighbor, administrators can use the show running-config | include "router bgp" and show running-config | include "neighbor" commands from the NX-OS command-line interface (CLI) and verify that the feature is enabled.
  
  The following example shows the BGP feature enabled with one BGP neighbor on a device running NX-OS Software:
  

  nxos-switch# show running-config | include "router bgp"
  router bgp 64512
  nxos-switch#
  nxos-switch# show running-config | include "neighbor"
  neighbor 209.165.201.1 remote-as 64497
  nxos-switch#
  
  

  Administrators can check the version of NX-OS Software running on their device by utilizing the show version command from the device CLI.  The following example identifies the 6.2(14) release:

  nxos-switch# show version
  Cisco Nexus Operating System (NX-OS) Software
  TAC support: http://www.cisco.com/tac
  Documents:
  http://www.cisco.com/en/US/products/ps9372/tsd_products_support_series_home.
  html
  Copyright (c) 2002-2015, Cisco Systems, Inc. All rights reserved.
  The copyrights to certain works contained in this software are
  owned by other third parties and used and distributed under
  license. Certain components of this software are licensed under
  the GNU General Public License (GPL) version 2.0 or the GNU
  Lesser General Public License (LGPL) Version 2.1. A copy of each
  such license is available at
  http://www.opensource.org/licenses/gpl-2.0.php and
  http://www.opensource.org/licenses/lgpl-2.1.php
  
  Software
    BIOS:      version 2.12.0
    kickstart: version 6.2(14)
    system:    version 6.2(14)
  .
  .
  .

  Products Confirmed Not Vulnerable

  The following Cisco products are not affected by this vulnerability:
  

  • Multilayer Director Switches
  • Nexus 4000 Series Switches
  • Unified Computing System (UCS) 6100 Series Fabric Interconnects
  • Unified Computing System (UCS) 6200 Series Fabric Interconnects

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

Indicators of Compromise

• Exploitation of this vulnerability could cause an affected device to reload and generate an URIB core file. To view the URIB core file, administrators can use the show core command in the NX-OS CLI. Contact the Cisco Technical Assistance Center (TAC) to review the URIB core file and determine whether the device has been compromised by exploitation of this vulnerability.

Workarounds

• Workarounds that address this vulnerability are not available.

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 re-seller 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 consult the Cisco Security Advisories and Responses archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.
  
  In all cases, customers should ensure that the devices to upgrade 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 Technical Assistance Center (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
  
  Customers should upgrade to an appropriate release as indicated in the applicable table 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-20161005-bgp: Cisco NX-OS Border Gateway Protocol Denial of Service Vulnerability
  cisco-sa-20161005-dhcp1: Cisco NX-OS Software Crafted DHCPv4 Packet Denial of Service Vulnerability
  cisco-sa-20161005-dhcp2: Cisco NX-OS Software Malformed DHCPv4 Packet Denial of Service Vulnerability
  cisco-sa-20161005-nxaaa: Cisco NX-OS Software-Based Products Authentication, Authorization, and Accounting Bypass Vulnerability
  cisco-sa-20161005-otv: Cisco Nexus 7000 and 7700 Series Switches Overlay Transport Virtualization Buffer Overflow Vulnerability
  
  In the following table, the left column lists major releases of Cisco NX-OS 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 which release includes fixes for those vulnerabilities.
  
  Cisco Nexus 1000 Series Switches : CSCux11417
  
  

  Cisco NX-OS Software Major Release - Nexus 1000 Series Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 4.2	Affected; migrate to 5.2(1)SV3(1.15)	5.2(1)SV3(1.15)
  5.2	5.2(1)SV3(1.15)	5.2(1)SV3(1.15)

  
  Cisco Nexus 3000, 3500, 2000, 5000, 5500, 6000, 7000, 9000 and 9000-ACI Series Switches : CSCuq77105
  
  

  Cisco NX-OS Software Major Release - Nexus 3000 Series Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 6.0	Affected; migrate to 6.0(2)U6(7)	6.0(2)U6(7)
  6.0	6.0(2)U6(7)	6.0(2)U6(7)
  6.1	Affected; migrate to 7.0(3)I2(2e) or 7.0(3)I4(1)	7.0(3)I4(1)
  7.0	7.0(3)I2(2e) or 7.0(3)I4(1)	7.0(3)I4(1)

  
  

  Cisco NX-OS Software Major Release - Nexus 3500 Platform Series Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 6.0	Affected; migrate to 6.0(2)A6(8) or 6.0(2)A8(1)	6.0(2)A8(1)
  6.0	6.0(2)A6(8) or 6.0(2)A8(1)	6.0(2)A8(1)

  
  

  Cisco NX-OS Software Major Release - Nexus 5000 Series Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 5.2	No fix available	5.2(1)N1(9a); Note: There is no fix for the vulnerability described in this advisory
  5.2	No fix available	5.2(1)N1(9a); Note: There is no fix for the vulnerability described in this advisory

  
  

  Cisco NX-OS Software Major Release - Nexus 2000, 5500, 5600 and 6000 Platform Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 5.2	Affected; migrate to 7.1(1)N1(1)	7.1(4)N1(1)
  5.2	Affected; migrate to 7.1(1)N1(1)	7.1(4)N1(1)
  6.0	Affected; migrate to 7.1(1)N1(1)	7.1(4)N1(1)
  7.0	Affected; migrate to 7.1(1)N1(1)	7.1(4)N1(1)
  7.1	7.1(1)N1(1)	7.1(4)N1(1)
  7.2	7.2(0)N1(1)	7.2(2)N1(1)
  7.3	7.3(0)N1(1)	7.3(0)N1(1)

  
  

  Cisco NX-OS Software Major Release - Nexus 7000 and 7700 Series Switches	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  Prior to 5.2	Affected; migrate to 6.2(10)	7.2(2)D1(1)
  5.2	Affected; migrate to 6.2(10)	7.2(2)D1(1)
  6.0	Affected; migrate to 6.2(10)	7.2(2)D1(1)
  6.1	Affected; migrate to 6.2(10)	7.2(2)D1(1)
  6.2	6.2(10)	7.2(2)D1(1)
  7.2	7.2(0)D1(1)	7.2(2)D1(1)
  7.3	7.3(0)D1(1)	7.3(1)D1(1)

  
  

  Cisco NX-OS Software Major Release - Nexus 9000 Series Switch ACI Mode	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  11.0	Affected; migrate to 11.1(1j)	11.1(1j)
  11.1	11.1(1j)	11.1(1j)
  11.2	Not Vulnerable	Not Vulnerable

  
  

  Cisco NX-OS Software Major Release - Nexus 9000 Series Switch NX-OS Mode	First Fixed Release for This Vulnerability	First Fixed Release for This Vulnerability and All Vulnerabilities Described in the Collection of Advisories
  6.1	Affected; migrate to 7.0(3)I2(2e) or 7.0(3)I4(1)	7.0(3)I4(1)
  7.0	7.0(3)I2(2e) or 7.0(3)I4(1)	7.0(3)I4(1)

  
  Release Recommendations
  
  For additional assistance in determining the best NX-OS Software release for a Cisco Nexus Switch, refer to the recommended release document for the switch:
  

  • Cisco Nexus 1000V for VMware Switches
  • Cisco Nexus 3000 Series and 3500 Series Switches
  • Cisco Nexus 5000 Series Switches
  • Cisco Nexus 5500 Platform Switches
  • Cisco Nexus 6000 Series Switches
  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 9000 Series Switches

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 discovered during internal testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161005-bgp

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2016-October-05

  Show Less