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             AUSCERT External Security Bulletin Redistribution

            Cisco Nexus 3000 and 9000 Series Switches Privilege
                         Escalation Vulnerability
                              27 August 2020


        AusCERT Security Bulletin Summary

Product:           Cisco Nexus 3000 Series Switches
                   Cisco Nexus 9000 Series Switches
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Root Compromise -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-3394  

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

Cisco Nexus 3000 and 9000 Series Switches Privilege Escalation Vulnerability

Priority:        High

Advisory ID:     cisco-sa-n3n9k-priv-escal-3QhXJBC

First Published: 2020 August 26 16:00 GMT

Last Updated:    2020 August 26 20:59 GMT

Version 1.1:     Final

Workarounds:     Yes

Cisco Bug IDs:   CSCvt77885



CVSS Score:


  o A vulnerability in the Enable Secret feature of Cisco Nexus 3000 Series
    Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode
    could allow an authenticated, local attacker to issue the enable command
    and get full administrative privileges. To exploit this vulnerability, the
    attacker would need to have valid credentials for the affected device.

    The vulnerability is due to a logic error in the implementation of the
    enable command. An attacker could exploit this vulnerability by logging in
    to the device and issuing the enable command. A successful exploit could
    allow the attacker to gain full administrative privileges without using the
    enable password.

    Note: The Enable Secret feature is disabled by default.

    Cisco has released software updates that address this vulnerability. There
    are workarounds that address this vulnerability.

    This advisory is available at the following link:

    This advisory is part of the August 2020 Cisco FXOS and NX-OS Software
    Security Advisory Bundled Publication, which includes seven Cisco Security
    Advisories that describe seven vulnerabilities. For a complete list of the
    advisories and links to them, see Cisco Event Response: August 2020 Cisco
    FXOS and NX-OS Software Security Advisory Bundled Publication .

Affected Products

  o Vulnerable Products

    This vulnerability affects the following Cisco products if they are running
    a vulnerable release of Cisco NX-OS Software and have the feature privilege
    command and the enable secret command configured:

       Nexus 3000 Series Switches
       Nexus 9000 Series Switches in standalone NX-OS mode

    For information about which Cisco software releases are vulnerable, see the
    Fixed Software section of this advisory.

    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 1000 Series
       Firepower 2100 Series
       Firepower 4100 Series
       Firepower 9300 Security Appliances
       MDS 9000 Series Multilayer Switches
       Nexus 1000 Virtual Edge for VMware vSphere
       Nexus 1000V Switch for Microsoft Hyper-V
       Nexus 1000V Switch for VMware vSphere
       Nexus 5500 Platform Switches
       Nexus 5600 Platform Switches
       Nexus 6000 Series Switches
       Nexus 7000 Series Switches
       Nexus 9000 Series Fabric Switches in Application Centric Infrastructure
        (ACI) mode
       UCS 6200 Series Fabric Interconnects
       UCS 6300 Series Fabric Interconnects
       UCS 6400 Series Fabric Interconnects


  o The enable secret command was added to Cisco NX-OS Software as a tool for
    migrating configurations from Cisco IOS Software to Cisco NX-OS Software
    only. The command serves no other purpose in Cisco NX-OS Software and
    should otherwise be disabled. The enable secret command will be removed in
    future releases.

    The enable secret command is used in Cisco IOS Software to set a password
    that grants a user privileged administrative access to a Cisco IOS Software
    system. In Cisco NX-OS Software, there is no concept of an enable-secret or
    enable-password setting. Privileges are managed using role-based access
    control (RBAC). The functional equivalent to enabling mode access on a
    Cisco IOS Software device is assignment of an account to the network-admin 
    (global privileged access) or vdc-admin (virtual device context [VDC]
    -specific privileged access) role in Cisco NX-OS Software.

    For additional information, see the Cisco Guide to Securing NX-OS Software
    Devices .

Indicators of Compromise

  o To determine whether this vulnerability has been exploited, use the show
    accounting log | include "enable" command. The following example shows the
    output of this command after a low-privileged user has elevated their
    privilege by using the enable command:

        nxos# show accounting log | include "enable" 
        type=update:id=console0:user=guest:cmd=enable (SUCCESS)
        type=update:id=console0:user=guest:cmd=enable 15 (SUCCESS)


  o There is a workaround that addresses this vulnerability.

    Cisco NX-OS Software uses RBAC to manage user accounts and privileges. For
    guidance, see the Configuring User Accounts and RBAC section of the Cisco
    NX-OS Security Configuration Guide.

    Once RBAC is configured, remove the enable secret command from the

Fixed Software

  o 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:

    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 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

    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

    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

    Cisco NX-OS Software

    To help customers determine their exposure to vulnerabilities in Cisco
    NX-OS Software, Cisco provides the Cisco Software Checker to identify any
    Cisco Security Advisories that impact a specific Cisco NX-OS Software
    release and the earliest release that fixes the vulnerabilities that are
    described in each advisory ("First Fixed"). If applicable, the tool also
    returns the earliest release that fixes all the vulnerabilities described
    in all the advisories identified ("Combined First Fixed").

    Customers can use the Cisco Software Checker to search advisories in the
    following ways:

       Choose the software, platform, and one or more releases
       Upload a .txt file that includes a list of specific releases
       Enter the output of the show version command

    After initiating a search, customers can customize the search to include
    all Cisco Security Advisories or one or more specific advisories.

    Customers can also use the following form to determine whether a release is
    affected by any Cisco Security Advisory by choosing the Cisco NX-OS
    Software and platform and then entering a release-for example, 7.0(3)I7(5) 
    for Cisco Nexus 3000 Series Switches or 14.0(1h) for Cisco NX-OS Software
    in ACI mode:

    [Cisco NX-OS Software            ] [MDS 9000 Series Multilayer Switches]

    [                    ] [Check]

    By default, the Cisco Software Checker includes results only for
    vulnerabilities that have a Critical or High Security Impact Rating (SIR).
    To include results for Medium SIR vulnerabilities, customers can use the
    Cisco Software Checker and check the Medium check box in the drop-down list
    under Impact Rating when customizing a search.

    Additional Resources

    For help determining the best Cisco NX-OS Software release for a Cisco
    Nexus Switch, see the following Recommended Releases documents. If a
    security advisory recommends a later release, Cisco recommends following
    the advisory guidance.

        Cisco MDS Series Switches
        Cisco Nexus 1000V for VMware Switch
        Cisco Nexus 3000 Series Switches
        Cisco Nexus 5500 Platform Switches
        Cisco Nexus 5600 Platform Switches
        Cisco Nexus 6000 Series Switches
        Cisco Nexus 7000 Series Switches
        Cisco Nexus 9000 Series Switches
        Cisco Nexus 9000 Series ACI-Mode Switches

    To determine the best release for Cisco UCS Software, see the Recommended
    Releases documents in the release notes for the device.

Exploitation and Public Announcements

  o 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.


  o This vulnerability was found during the resolution of a Cisco TAC support

Cisco Security Vulnerability Policy

  o 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.

Related to This Advisory

  o Cisco Event Response: August 2020 Cisco FXOS and NX-OS Software Security
    Advisory Bundled Publication


  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/

Revision History

  o +---------+-------------------------+--------------+--------+-------------+
    | Version |       Description       |   Section    | Status |    Date     |
    | 1.1     | Fixed Software Checker  | Fixed        | Final  | 2020-AUG-26 |
    |         | link.                   | Software     |        |             |
    | 1.0     | Initial public release. | -            | Final  | 2020-AUG-26 |

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