Summary

• A vulnerability in the Link Layer Discovery Protocol (LLDP) implementation for Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition when the device unexpectedly reloads.

  The vulnerability is due to improper input validation of certain type, length, value (TLV) fields of the LLDP frame header. An attacker could exploit this vulnerability by sending a crafted LLDP packet to an interface on the targeted device. A successful exploit could allow the attacker to cause the switch to reload unexpectedly.

  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-20181017-fxnx-os-dos

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco FXOS or NX-OS Software and LLDP is enabled on an interface. The LLDP protocol is not enabled by default on all FXOS and NX-OS platforms. Administrators are advised to refer to the device’s documentation for more information.

  Refer to the Fixed Software section of this security advisory for more information about affected releases.

  • Firepower 4100 Series Next-Generation Firewall
  • Firepower 9300 Security Appliance
  • MDS 9000 Series Multilayer Switches
  • Nexus 2000 Series Switches
  • Nexus 3000 Series Switches
  • Nexus 3500 Platform Switches
  • Nexus 5500 Platform Switches
  • Nexus 5600 Platform Switches
  • Nexus 6000 Platform Switches
  • Nexus 7000 Series Switches
  • Nexus 7700 Series Switches
  • Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
  • Unified Computing System (UCS) 6100 Series Fabric Interconnects
  • UCS 6200 Series Fabric Interconnects
  • UCS 6300 Series Fabric Interconnects

  Determining Whether LLDP Is Enabled

  On the Nexus 9000 Series Fabric Switches in ACI mode, the administrator can use the show lldp interface ethernet port/interface command to determine the LLDP status. In the following example, LLDP is enabled if the transmit (tx) and receive (rx) status is Y.

  # show lldp interface ethernet port/interface
  Interface Information:
  Enable (tx/rx/dcbx): Y/Y/N    Port Mac address: 00:fe:c8:09:e2:92

  Determining the Cisco FXOS Software Release

  Administrators can determine the release of Cisco FXOS Software that is running on a device by using the following commands in the device CLI or by navigating to the Overview tab in the Admin portal. The following example shows the output of the show version CLI command for a device that is running Cisco FXOS Software Release 2.2(2.14), as identified in the Package-Vers field of the command output:

  QP4120B1 # scope system
  QP4120B1 /system # show version
  FPRM:
  Running-Vers: 4.2(2.15)
  Package-Vers: 2.2(2.14)
  Activate-Status: Ready

  Determining the Cisco NX-OS Software Release

  Administrators can determine the release of Cisco NX-OS Software running on a device by using the show version command in the device CLI. The following example identifies the 11.2(2) release:

  nxos-n9k-aci# show version
  Cisco Nexus Operating System (NX-OS) Software
  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 N/A
  kickstart: version 11.2(2) [build 11.2(1.184)]
  system:    version 11.2(2) [build 11.2(1.184)]

  Determining the Cisco Application Policy Infrastructure Controller Software Release

  There is a one-to-one mapping between the software for Cisco Application Policy Infrastructure Controller (APIC) and Cisco Nexus 9000 Series Fabric Switches in ACI mode. To determine which Cisco APIC release is running on a device, administrators can remove the leftmost 1 from the Cisco NX-OS Software version number. In the previous example, the Cisco APIC Software release is 1.2(2).

  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 the following Cisco products:

  • Firepower 2100 Series
  • Nexus 1000V Switch for Microsoft Hyper-V
  • Nexus 1000V Switch for VMware vSphere
  • Nexus 3600 Platform Switches
  • Nexus 9000 Series Switches in standalone NX-OS mode
  • Nexus 9500 R-Series Line Cards and Fabric Modules
  • UCS 6400 Series Fabric Interconnects

Indicators of Compromise

• Exploitation of this vulnerability could cause an affected device to reload and generate a core file. Contact the Cisco Technical Assistance Center (TAC) to review the core file and determine whether the device has been compromised by exploitation of this vulnerability.

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

  In the following tables, the left column lists releases of Cisco FXOS or NX-OS Software. The right column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes the fix for this vulnerability.

  Firepower 4100 Series Next-Generation Firewall and Firepower 9300 Security Appliance: CSCvf23367

  Cisco FXOS Software Release	First Fixed Release for This Vulnerability
  Prior to 2.3	2.3.1.58
  2.3	Not vulnerable

  MDS 9000 Series Multilayer Switches: CSCuc98542

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  5.2	6.2(1)
  6.2	6.2(1)
  7.3	Not vulnerable
  8.1	Not vulnerable
  8.2	Not vulnerable

  Nexus 3000 Series Switches: CSCuc98542

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  5.0(3)	6.0(2)U1(2)
  6.0(2)	6.0(2)U1(2)
  7.0(3)	Not vulnerable
  9.2(1)	Not vulnerable

  Nexus 3500 Platform Switches: CSCuc98542

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  5.0(3)	6.0(2)A1(1b)
  6.0(2)	6.0(2)A1(1b)
  7.0(3)	Not vulnerable
  9.2(1)	Not vulnerable

  Nexus 2000, 5500, 5600, and 6000 Series Switches: CSCuc98542

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  5.0	7.0(0)N1(1)
  5.1	7.0(0)N1(1)
  6.0	7.0(0)N1(1)
  7.0	Not vulnerable
  7.1	Not vulnerable
  7.2	Not vulnerable
  7.3	Not vulnerable

  Nexus 7000 and 7700 Series Switches: CSCuc98542

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  5.2	5.2(9)
  6.1	6.1(3)
  6.2	Not vulnerable
  7.2	Not vulnerable
  7.3	Not vulnerable
  8.0	Not vulnerable
  8.1	Not vulnerable
  8.2	Not vulnerable

  Nexus 9000 Series Fabric Switches in ACI Mode: CSCvj94174

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability
  Prior to 13.2/3.2	13.2(2l) / 3.2(2l)
  13.2/3.2	13.2(2l) / 3.2(2l)

  UCS 6100, 6200, and 6300 Series Fabric Interconnects: CSCvj96148

  Cisco NX-OS UCS Software Release	First Fixed Release for This Vulnerability
  Prior to 2.2	2.2(8l)
  2.2	2.2(8l)
  3.1	3.1(3j)
  3.2	3.2(3g)
  4.0	4.0(1a)

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-20181017-fxnx-os-dos

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2018-October-17

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