Cisco Security Advisory
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CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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A vulnerability in the Fibre Channel over Ethernet (FCoE) N-port Virtualization (NPV) protocol implementation in Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition.
The vulnerability is due to an incorrect processing of FCoE packets when the fcoe-npv feature is uninstalled. An attacker could exploit this vulnerability by sending a stream of FCoE frames from an adjacent host to an affected device. An exploit could allow the attacker to cause packet amplification to occur, resulting in the saturation of interfaces and a DoS condition.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is part of the March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication, which includes 25 Cisco Security Advisories that describe 26 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190306-nxos-npv-dos
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Vulnerable Products
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software:
- Nexus 9000 Series Switches in standalone NX-OS mode
Only the following Nexus 9000 Series PIDs are vulnerable:
- N9K-C92160YC-X
- N9K-C9272Q
- N9K-C9236C
- N9K-C93180YC-EX
- N9K-X9732C-EX
- N9K-C93180LC-EX
- N9K-C93180YC-FX
- N9K-X9736C-FX
To view the PIDs of the system, use the show inventory CLI command:
9K-A# show inventory
NAME: "Chassis", DESCR: "Nexus9000 C93128TX Chassis"
PID: N9K-C93128TX , VID: V02 , SN: SAL1822TF13
NAME: "Slot 1", DESCR: "1/10G-T Ethernet Module"
PID: N9K-C93128TX , VID: V02 , SN: SAL1822TF13
NAME: "Slot 2", DESCR: "40G Ethernet Expansion Module"
PID: N9K-M12PQ , VID: V01 , SN: SAL1910AMHDNote: For this vulnerability to occur, all of the following conditions must be met:
- The affected devices are configured as vPC peer switches.
- The fcoe-npv feature must be uninstalled.
See Details for more information.
For information about which Cisco NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.
Determining the Cisco NX-OS Software Release
Administrators can check the release of Cisco NX-OS Software that is running on a device by using the show version command in the device CLI. The following example shows the output of this command on a device that is running Cisco NX-OS Software Release 7.0(3)I5(1):
nxos-switch# show version Cisco Nexus Operating System (NX-OS) Software TAC support: http://www.cisco.com/tac Copyright (C) 2002-2016, Cisco and/or its affiliates. All rights reserved. The copyrights to certain works contained in this software are owned by other third parties and used and distributed under their own licenses, such as open source. This software is provided "as is," and unless otherwise stated, there is no warranty, express or implied, including but not limited to warranties of merchantability and fitness for a particular purpose. Certain components of this software are licensed under the GNU General Public License (GPL) version 2.0 or GNU General Public License (GPL) version 3.0 or the GNU Lesser General Public License (LGPL) Version 2.1 or Lesser General Public License (LGPL) Version 2.0. A copy of each such license is available at http://www.opensource.org/licenses/gpl-2.0.php and http://opensource.org/licenses/gpl-3.0.html and http://www.opensource.org/licenses/lgpl-2.1.php and http://www.gnu.org/licenses/old-licenses/library.txt. Software BIOS: version 07.57 NXOS: version 7.0(3)I5(1) [build 7.0(3)I5(0.9)] BIOS compile time: 06/29/2016 NXOS image file is: bootflash:///nxos.7.0.3.I5.0.9.bin NXOS compile time: 8/1/2016 23:00:00 [08/02/2016 00:30:32] . . .
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
- Firepower 4100 Series Next-Generation Firewall
- Firepower 9300 Security Appliance
- MDS 9000 Series Multilayer Switches
- Nexus 1000V Switch for Microsoft Hyper-V
- Nexus 1000V Switch for VMware vSphere
- Nexus 2000 Series Fabric Extenders
- Nexus 3000 Series Switches
- Nexus 3500 Platform Switches
- Nexus 3600 Platform Switches
- Nexus 5500 Platform Switches
- Nexus 5600 Platform Switches
- Nexus 6000 Series Switches
- Nexus 7000 Series Switches
- Nexus 7700 Series Switches
- Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
- Nexus 9500 R-Series Line Cards and Fabric Modules
- UCS 6200 Series Fabric Interconnects
- UCS 6300 Series Fabric Interconnects
- UCS 6400 Series Fabric Interconnects
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The affected devices are vulnerable when configured as outlined in the Vulnerable Products section. The following commands will help identify these conditions:
To verify the status of a vPC configuration, use the show vpc brief CLI command:
9K-A# show vpc brief
Legend:
(*) - local vPC is down, forwarding via vPC peer-link
vPC domain id : 10
Peer status : peer adjacency formed ok
vPC keep-alive status : peer is alive
Configuration consistency status : success
Per-vlan consistency status : success
Type-2 inconsistency reason : Consistency Check Not Performed
vPC role : primary
Number of vPCs configured : 1
Peer Gateway : Enabled
Dual-active excluded VLANs : -
Graceful Consistency Check : Enabled
Auto-recovery status : Disabled
Delay-restore status : Timer is off.(timeout = 30s)
Delay-restore SVI status : Timer is off.(timeout = 10s)
vPC Peer-link status
---------------------------------------------------------------------
id Port Status Active vlans
-- ---- ------ --------------------------------------------------
1 Po1 up 1
vPC status
----------------------------------------------------------------------
id Port Status Consistency Reason Active vlans
-- ---- ------ ----------- ------ ------------
10 Po10 up success success 1To verify the status of the fcoe-npv feature, use the show feature-set CLI command:
9K-A# show feature-set
Feature Set Name ID State -------------------- -------- -------- fex 3 uninstalled mpls 4 uninstalled
fabric 7 uninstalled
fcoe-npv 8 uninstalled
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If the devices are configured as outlined in the Vulnerable Products section, a possible indicator of compromise would be a relativity low Rx input rate, except for the vPC peer link, coupled with a high Tx rate for all enabled interfaces on the vPC pair of affected Nexus 9000 Series Switches.
To see interface throughput statistics, use the show interface counter table CLI command: (egrep -v "0.0 0.0% 0.0 0.0%", excludes interfaces with zero statistics for Rx and Tx columns)
9K-A# sh int counter table | egrep -v "0.0 0.0% 0.0 0.0%"
Collecting and processing interface statistics ...
------------------------------------------------------------------------
Port Description Intvl Rx Mbps Rx % Tx Mbps Tx %
------------------------------------------------------------------------
Ethernet1/49 vPC_Peer_Link 30/30 36078.7 90.2% 36078.7 90.2%
Ethernet1/50/1 N/A 30/30 2.5 0.0% 9019.6 90.2%
Ethernet1/50/2 N/A 30/30 0.0 0.0% 9019.6 90.2%
port-channel36 N/A 30/30 2.5 0.0% 9019.6 90.2%
port-channel100 vPC_Peer_Link 30/30 36078.7 90.2% 36078.7 90.2%
9K-B# sh int counter table | egrep -v "0.0 0.0% 0.0 0.0%"
Collecting and processing interface statistics ...-------------------------------------------------------------------------
Port Description Intvl Rx Mbps Rx % Tx Mbps Tx %
-------------------------------------------------------------------------
Ethernet1/49 vPC_Peer_Link 30/30 36078.3 90.2% 36078.3 90.2%
Ethernet1/50/1 N/A 30/30 0.0 0.0% 9019.6 90.2%
port-channel36 N/A 30/30 0.0 0.0% 9019.6 90.2%
port-channel100 vPC_Peer_Link 30/30 36078.3 90.2% 36078.3 90.2%Another potential indication would be output discards. To check for output discards, use the show interface counter errors non-zero CLI command:
9K-A# sh int counter errors non-zero
-------------------------------------------------------------------------
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
-------------------------------------------------------------------------
Eth1/49 0 0 0 0 0 426242
Eth1/50/1 0 0 0 0 0 9916163951
Eth1/50/2 0 0 0 0 0 9934560747
Po36 0 0 0 0 0 9916163951
Po100 0 0 0 0 0 426242
9K-B# sh int counter errors non-zero
-------------------------------------------------------------------------
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
-------------------------------------------------------------------------
Eth1/50/1 0 0 0 0 0 9915689573
Po36 0 0 0 0 0 9915689573If there are any questions regarding the output of your device or the information above, please contact Cisco TAC:
https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html
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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.htmlAdditionally, 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.htmlCustomers 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 are advised to upgrade to an appropriate release as indicated in the applicable table in this section. To help ensure a complete upgrade solution, customers should consider that this advisory is part of a bundled publication. The following page provides a complete list of bundle advisories: Cisco Event Response: March 2019 Cisco FXOS and NX-OS Software Security Advisory Bundled Publication.
In the following tables, the left column lists releases of Cisco FXOS Software or Cisco NX-OS Software. The center 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. The right column indicates whether a release is affected by all the vulnerabilities described in this bundle and which release includes fixes for those vulnerabilities.
Although the releases listed in the right column of each table include fixes for the vulnerabilities, the fix related to the Cisco NX-OS Software Image Signature Verification Vulnerability requires a BIOS upgrade as part of the software upgrade. Customers who are upgrading the software for any of the following products are advised to refer to this advisory for further details about the BIOS upgrade and affected product IDs and BIOS versions:
- Nexus 3000 Series Switches
- Nexus 9000 Series Fabric Switches in ACI mode
- Nexus 9000 Series Switches in standalone NX-OS mode
- Nexus 9500 R-Series Line Cards and Fabric Modules
Cisco NX-OS Software Release First Fixed Release for This Vulnerability First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories Prior to 7.0(3)I4
Not vulnerable 7.0(3)I7(6)
7.0(3)I4 Not vulnerable 7.0(3)I7(6)
7.0(3)I5 7.0(3)I7(5) 7.0(3)I7(6)
7.0(3)I6 7.0(3)I7(5) 7.0(3)I7(6) 7.0(3)I7 7.0(3)I7(5) 7.0(3)I7(6)
9.2 9.2(2)
9.2(2)
Additional Resources
For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, administrators can refer to the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.
For help determining the best Cisco NX-OS Software release for Cisco UCS, refer to the Recommended Releases documents in the release notes for the device.Cisco MDS Series Switches
Cisco Nexus 1000V for VMware Switch
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
Cisco Nexus 9000 Series ACI-Mode Switches
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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.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2019-March-06
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