A vulnerability in the filesystem permissions of Cisco NX-OS Software could allow an authenticated, local attacker to gain read and write access to a critical configuration file. The vulnerability is due to a failure to impose strict filesystem permissions on the targeted device. An attacker could exploit this vulnerability by accessing and modifying restricted files. A successful exploit could allow an attacker to use the content of this configuration file to bypass authentication and log in as any user of the device. 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-file-access 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 filesystem permissions of Cisco NX-OS Software could allow an authenticated, local attacker to gain read and write access to a critical configuration file.
The vulnerability is due to a failure to impose strict filesystem permissions on the targeted device. An attacker could exploit this vulnerability by accessing and modifying restricted files. A successful exploit could allow an attacker to use the content of this configuration file to bypass authentication and log in as any user of the device.
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-file-access
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 vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco NX-OS Software:
For information about which Cisco NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.
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 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 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:
MDS 9000 Series Multilayer Switches: CSCvi42331
| Cisco NX-OS Software | First Fixed Release for This Vulnerability |
First Fixed Release for All Vulnerabilities Described in the Bundle of Advisories |
|---|---|---|
| 5.2 | 6.2(25) | 6.2(27) |
| 6.2 | 6.2(25) |
6.2(27) |
| 7.3 | 8.1(1b) | 8.3(2) |
| 8.1 | 8.1(1b) | 8.3(2) |
| 8.2 | 8.3(1) | 8.3(2) |
| 8.3 | 8.3(1) |
8.3(2) |
Nexus 3000 Series Switches: CSCvi42317
| 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)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I5 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I6 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I7 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2(1) | Not vulnerable | 9.2(2) |
Nexus 3500 Platform Switches: CSCvi96476
| 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 6.0(2)A8 | 6.0(2)A8(10) | 6.0(2)A8(11) |
| 6.0(2)A8 | 6.0(2)A8(10) | 6.0(2)A8(11) |
| 7.0(3) | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2 | Not vulnerable | 9.2(2) |
Nexus 3600 Platform Switches: CSCvi96486
| 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)F3 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 9.2(1) | Not vulnerable | 9.2(2) |
Nexus 2000, 5500, 5600, and 6000 Series Switches: CSCvi96478
| 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 5.2 | 7.1(5)N1(1b) | 7.1(5)N1(1b) |
| 5.2 |
7.1(5)N1(1b) | 7.1(5)N1(1b) |
| 6.0 |
7.1(5)N1(1b) | 7.1(5)N1(1b) |
| 7.0 | 7.1(5)N1(1b) | 7.1(5)N1(1b) |
| 7.1 | 7.1(5)N1(1b) | 7.1(5)N1(1b) |
| 7.2 | 7.3(3)N1(1) | 7.3(5)N1(1) |
| 7.3 | 7.3(3)N1(1) | 7.3(5)N1(1) |
Nexus 7000 and 7700 Series Switches: CSCvi42331
| 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 6.2 | 6.2(22) | 6.2(22) |
| 6.2 |
6.2(22) | 6.2(22) |
| 7.2 |
7.3(3)D1(1) | 8.2(3) |
| 7.3 | 7.3(3)D1(1) | 8.2(3) |
| 8.0 |
8.1(2) | 8.2(3) |
| 8.1 |
8.1(2) | 8.2(3) |
| 8.2 |
8.2(3) | 8.2(3) |
| 8.3 |
Not vulnerable | 8.3(2) |
Nexus 9000 Series Switches in Standalone NX-OS Mode: CSCvi42317
| 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)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I4 | 7.0(3)I4(9) | 7.0(3)I7(6) |
| 7.0(3)I5 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I6 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 7.0(3)I7 | 7.0(3)I7(4) | 7.0(3)I7(6) |
| 9.2 | Not vulnerable | 9.2(2) |
Nexus 9500 R-Series Line Cards and Fabric Modules: CSCvi96486
| 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(3c)1 | 7.0(3)F3(5) |
| 7.0(3)F2 | 7.0(3)F3(3c)1 | 7.0(3)F3(5) |
| 7.0(3)F3 | 7.0(3)F3(3c)1 | 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 |
|---|---|---|---|---|
| 1.4 | Updated the fixed software table for Nexus 7000 and 7700 for the 8.2 software release. | Fixed Software | Final | 2019-March-19 |
| 1.3 | Updated affected software version. | Final | 2019-March-14 |
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