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             AUSCERT External Security Bulletin Redistribution

          Cisco Small Business Switches Secure Shell Certificate
                    Authentication Bypass Vulnerability
                                3 May 2019


        AusCERT Security Bulletin Summary

Product:           Cisco Small Business Switches
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Administrator Compromise -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-1859  

Original Bulletin: 

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

Cisco Small Business Switches Secure Shell Certificate Authentication Bypass

Priority:        High

Advisory ID:     cisco-sa-20190501-scbv

First Published: 2019 May 1 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds availableCisco Bug IDs:   CSCvo28588CSCvp35704



CVSS Score:


    A vulnerability in the Secure Shell (SSH) authentication process of Cisco
    Small Business Switches software could allow an attacker to bypass
    client-side certificate authentication and revert to password

    The vulnerability exists because OpenSSH mishandles the authentication
    process. An attacker could exploit this vulnerability by attempting to
    connect to the device via SSH. A successful exploit could allow the
    attacker to access the configuration as an administrative user if the
    default credentials are not changed.

    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:

Affected Products

  o Vulnerable Products

    This vulnerability affects the following Cisco products running the
    software releases shown in the left column.

     Cisco Software Release                    Cisco Switches
                              Small Business 200 Series Smart Switches
    Prior to         Small Business 300 Series Managed Switches
                              Small Business 500 Series Managed Switches
                              250 Series Smart Switches
    Prior to         350 Series Managed Switches
                              350X Series Managed Switches
                              550X Series Stackable Managed Switches

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.


  o There are no workarounds available; however, if client-side certificate
    authentication is enabled, disable it and use strong password
    authentication. Client-side certificate authentication is disabled by

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 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

    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:

    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

    Fixed Releases

    Cisco fixed this vulnerability in the following software releases.

     Cisco Software Release                    Cisco Switches
                              Small Business 200 Series Smart Switches                  Small Business 300 Series Managed Switches
                              Small Business 500 Series Managed Switches
                              250 Series Smart Switches                  350 Series Managed Switches
                              350X Series Managed Switches
                              550X Series Stackable Managed Switches

    Customers can download the Cisco Small Business Switches Software from the
    Software Center on Cisco.com by doing the following:

     1. Click Browse all .
     2. Choose Switches > LAN Switches - Small Business.
     3. Choose one of the following:
           200 Series Smart Switches
           250 Series Smart Switches
           350X Series Stackable Managed Switches
           300 Series Managed Switches
           500 Series Stackable Managed Switches
           550X Series Stackable Managed Switches
     4. Choose the model number.
     5. Choose the firmware or the MIB software type.
     6. Access releases by using the left pane of the Policy Suite for Mobile 

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 Cisco would like to thank Katie Sexton and Jimi Sebree of Tenable Research
    for reporting these vulnerabilities.

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.


  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-scbv

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    | 1.0      | Initial public release.   | -        | Final  | 2019-May-01  |

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