A vulnerability in the Image Signature Verification feature of Cisco NX-OS Software could allow an authenticated, local attacker with administrator-level credentials to install a malicious software image on an affected device. The vulnerability is due to improper verification of digital signatures for software images. An attacker could exploit this vulnerability by loading an unsigned software image on an affected device. A successful exploit could allow the attacker to boot a malicious software image. Note: The fix for this vulnerability requires a BIOS upgrade as part of the software upgrade. For additional information, see the Details section of this advisory. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190306-nxos-sig-verif 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.
A vulnerability in the Image Signature Verification feature of Cisco NX-OS Software could allow an authenticated, local attacker with administrator-level credentials to install a malicious software image on an affected device.
The vulnerability is due to improper verification of digital signatures for software images. An attacker could exploit this vulnerability by loading an unsigned software image on an affected device. A successful exploit could allow the attacker to boot a malicious software image.
Note: The fix for this vulnerability requires a BIOS upgrade as part of the software upgrade. For additional information, see the Details section of this advisory.
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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190306-nxos-sig-verif
This vulnerability affects the Cisco products that are listed in the following subsection when the product meets all the following conditions:
To help customers identify device characteristics that could indicate a vulnerable device, this advisory provides details about determining the device’s PID, the running BIOS version, and the running Cisco NX-OS Software release.
The tables in this section provide details about the affected PIDs of the Cisco products that are affected by the vulnerability described in this advisory. PIDS that are not shown in these tables are not known to be affected by this vulnerability. BIOS versions prior to the first fixed version are affected by this vulnerability.
Nexus 3000 Series Switches
| Nexus 3000 PID | First Fixed BIOS Version |
|---|---|
| N3K-C31128PQ-10GE | 7.63 |
| N3K-C3132C-Z N3K-C3164Q-40GE N3K-C3232C N3K-C3264Q |
8.34 |
Nexus 9000 Series Fabric Switches in ACI Mode and Nexus 9000 Series Switches in Standalone NX-OS Mode
| Nexus 9000 PID | First Fixed BIOS Version |
|---|---|
| N9K-C92160YC-X N9K-C92304QC N9K-C9232C N9K-C9236C N9K-C9272Q N9K-C93108TC-EX N9K-C93120TX N9K-C93128TX N9K-C93180YC-EX N9K-C9332PQ N9K-C9372PX N9K-C9372PX-E N9K-C9372TX N9K-C9372TX-E N9K-C9396PX N9K-C9396TX |
7.63 |
| N9K-SUP-A
N9K-SUP-B |
8.34 |
Nexus 9500 R-Series Line Cards and Fabric Modules
| Nexus 9500 PID | First Fixed BIOS Version |
|---|---|
| N9K-SUP-B | 8.34 |
For information about which Cisco NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.
Administrators can check the product ID of a device by using the show inventory command in the device CLI. The following example shows the output of the command for a device that has the PID N3K-C3232C:
Vulmon
switch# show inventory
NAME: "Chassis", DESCR: "Nexus3000 C3232C Chassis"
PID: N3K-C3232C , VID: V02 , SN: FOC20291JA0
NAME: "Slot 1", DESCR: "32x40/100G QSFP28 2x10G SFP+ Ethernet Module"
PID: N3K-C3232C , VID: V02 , SN: FOC20291JA0
NAME: "Power Supply 1", DESCR: "Nexus3000 C3232C Chassis Power Supply"
PID: NXA-PAC-650W-PI , VID: V01 , SN: LIT20362Z6G
Administrators can check the Cisco NX-OS BIOS version that is running on a device by using the show version command in the device CLI. The following example shows the output of the command for a device that is running Cisco NX-OS BIOS version 8.32:
N9K-A# show version Cisco Nexus Operating System (NX-OS) Software. . . Software BIOS: version 08.32
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] . . .
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:
Cisco Nexus 3000 Series NX-OS Software Upgrade and Downgrade Guide, Release 9.x
Cisco Nexus 9000 Series NX-OS Software Upgrade and Downgrade Guide, Release 9.x
Note: Customers who are running a vulnerable PID with a fixed software release may not have upgraded the BIOS when the software was installed. Customers are advised to confirm that the BIOS is running a fixed BIOS version (first fixed or later).
The Determining the Cisco NX-OS BIOS Version section of this advisory provides information about checking the installed BIOS version.Trust Center Downloads provides methods to determine the authenticity of Cisco software image files.
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 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.
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 this advisory requires a BIOS upgrade as part of the software upgrade. Customers who are upgrading the software for any of the products listed in this section are advised to review this entire advisory for further details about the BIOS upgrade and affected product IDs and BIOS versions.
Nexus 3000 Series Switches: CSCvj14135
| 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 | 7.0(3)I7(5) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I7(5) | 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(1) | Not vulnerable | 9.2(2) |
Nexus 9000 Series Fabric Switches in ACI Mode: CSCvk70903
| 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 13.1 |
13.2(1l) | 14.0(3d) |
| 13.1 |
13.2(1l) | 14.0(3d) |
| 13.2 | Not vulnerable |
14.0(3d) |
| 14.0 | Not vulnerable | 14.0(3d) |
Nexus 9000 Series Switches in Standalone NX-OS Mode: CSCvj14135
| 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 | 7.0(3)I7(5) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I7(5) | 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 | Not vulnerable | 9.2(2) |
Nexus 9500 R-Series Line Cards and Fabric Modules: CSCvk70905
| Cisco NX-OS Software Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| 7.0(3)F1 | 7.0(3)F3(5) | 7.0(3)F3(5) |
| 7.0(3)F2 | 7.0(3)F3(5) | 7.0(3)F3(5) |
| 7.0(3)F3 | 7.0(3)F3(5) |
7.0(3)F3(5) |
| 9.2 | Not vulnerable | 9.2(2) |
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
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.
This vulnerability was found during internal security testing.
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.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.2 | Updated Vulnerable Products section to include PID - N3K-C3232C. | Vulnerable Products | Final | 2019-April-15 |
| 1.1 | Updated the fixed software table for Nexus 9000 (in standalone NX-OS mode) for software releases prior to 7.0(3)I4. | Fixed Software | Final | 2019-March-19 |
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