Summary

• A vulnerability in the write-erase feature of Cisco FXOS Software and Cisco NX-OS Software could allow an authenticated, local attacker to configure an unauthorized administrator account for an affected device.

  The vulnerability exists because the affected software does not properly delete sensitive files when certain CLI commands are used to clear the device configuration and reload a device. An attacker could exploit this vulnerability by logging into an affected device as an administrative user and configuring an unauthorized account for the device. The account would not require a password for authentication and would be accessible only via a Secure Shell (SSH) connection to the device. A successful exploit could allow the attacker to configure an unauthorized account that has administrative privileges, does not require a password for authentication, and does not appear in the running configuration or the audit logs for the affected 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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180620-nxosadmin

  This advisory is part of the June 2018 Cisco FXOS and NX-OS Software Security Advisory Collection, which includes 24 Cisco Security Advisories that describe 24 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: June 2018 Cisco FXOS and NX-OS Software Security Advisory Collection.

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco FXOS Software or Cisco NX-OS Software:

  • Firepower 4100 Series Next-Generation Firewalls
  • Firepower 9300 Security Appliance
  • Nexus 1000V Series Switches
  • Nexus 1100 Series Cloud Services Platforms
  • Nexus 2000 Series Fabric Extenders
  • Nexus 3500 Platform Switches
  • Nexus 4000 Series Switches
  • Nexus 5500 Platform Switches
  • Nexus 5600 Platform Switches
  • Nexus 6000 Series Switches
  • UCS 6100 Series Fabric Interconnects
  • UCS 6200 Series Fabric Interconnects
  • UCS 6300 Series Fabric Interconnects

  For information about which Cisco FXOS and NX-OS Software releases are vulnerable, see the Fixed Software section of this advisory.

  Determining the Cisco FXOS Software Release

  Administrators can check 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 on 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 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 7.3(2)D1(1):

  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) 2002-2017, 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 7.3(2)D1(1)
    system:    version 7.3(2)D1(1)
  .
  .
  .
  
  

  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 Firewalls
  • MDS 9000 Series Multilayer Switches
  • Nexus 3000 Series Switches
  • Nexus 3600 Platform Switches
  • Nexus 7000 Series Switches
  • Nexus 7700 Series Switches
  • Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) mode
  • Nexus 9000 Series Switches in standalone NX-OS mode
  • Nexus 9500 R-Series Line Cards and Fabric Modules

  Cisco has not investigated whether this vulnerability affects Cisco Nexus 5010 Switches and Cisco Nexus 5020 Switches because those products have reached end-of-life status. For more information, refer to the End-of-Sale and End-of-Life Announcement for the Cisco Nexus 5010 and Nexus 5020 Switches.

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

  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, consider that this advisory is part of a collection. For a complete list of the advisories in the collection and links to them, see Cisco Event Response: June 2018 Cisco FXOS and NX-OS Software Security Advisory Collection.

  In the following tables, the left column lists releases of Cisco FXOS or 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 collection of advisories and which release includes fixes for those vulnerabilities.

  Firepower 4100 Series Next-Generation Firewalls: CSCve35753

  Cisco FXOS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  1.1	2.0.1.159	2.0.1.159 or 2.3.1.58
  2.0	2.0.1.159	2.0.1.159 or 2.3.1.58
  2.1.1	2.1.1.86	2.1.1.86 or 2.3.1.58
  2.2	2.2.2.17	2.2.2.17 or 2.3.1.58
  2.2.2	2.2.2.17	2.2.2.17 or 2.3.1.58
  2.3	Not vulnerable	Not vulnerable

  Firepower 9300 Security Appliance: CSCve35753

  Cisco FXOS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  1.1	2.0.1.159	2.0.1.159 or 2.3.1.58
  2.0	2.0.1.159	2.0.1.159 or 2.3.1.58
  2.1.1	2.1.1.86	2.1.1.86 or 2.3.1.58
  2.2	2.2.2.17	2.2.2.17 or 2.3.1.58
  2.2.2	2.2.2.17	2.2.2.17 or 2.3.1.58
  2.3	Not vulnerable	Not vulnerable

  Nexus 1000V Series Switches and Nexus 1100 Series Cloud Services Platforms: CSCvd34845

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  Prior to 5.2	5.2(1)SV3(3.1)	5.2(1)SV3(3.15)
  5.2	5.2(1)SV3(3.1)	5.2(1)SV3(3.15)

  Nexus 3500 Platform Switches: CSCvd34857

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  6.0(2)	6.0(2)A8(7)	7.0(3)I7(4)
  7.0(3)	7.0(3)I7(2)	7.0(3)I7(4)

  Nexus 4000 Series Switches: CSCvd34879

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  4.1	4.1(2)E1(1r)	4.1(2)E1(1s)

  Nexus 2000 Series Fabric Extenders and Nexus 5500, 5600, and 6000 Series Switches: CSCvd13993

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  6.0	7.1(5)N1(1)	7.3(3)N1(1)
  7.0	7.1(5)N1(1)	7.3(3)N1(1)
  7.1	7.1(5)N1(1) or later	7.3(3)N1(1)
  7.2	7.3(2)N1(1)	7.3(3)N1(1)
  7.3	7.3(2)N1(1)	7.3(3)N1(1)

  UCS 6100, 6200, and 6300 Fabric Interconnects: CSCvd34862

  Cisco NX-OS Software Release	First Fixed Release for This Vulnerability	First Fixed Release for All Vulnerabilities Described in the Collection of Advisories
  Prior to 2.2	3.1(3a)1	3.2(2b)
  2.2	3.1(3a)1	3.2(2b)
  2.5	3.1(3a)	3.2(2b)
  3.0	3.1(3a)	3.2(2b)
  3.1	3.1(3a)	3.2(2b)
  3.2	3.2(1d)	3.2(2b)

  
  ¹ Cisco UCS 6100 Series Fabric Interconnects are vulnerable if they are running Cisco NX-OS Software Release 2.2 or prior. However, a fix is not available for Cisco UCS 6100 Series Fabric Interconnects because the product has reached end-of-life status. For more information, refer to the End-of-Sale and End-of-Life Announcement for the Cisco UCS 6100 Series Fabric Interconnects.

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 internal security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180620-nxosadmin

Revision History

• Version	Description	Section	Status	Date
  1.1	Updated Fixed Releases for FXOS platforms.	Fixed Software	Final	2018-July-05
  1.0	Initial public release.	—	Final	2018-June-20

  Show Less

---