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AUSCERT External Security Bulletin Redistribution
ESB-2019.1536
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:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-scbv
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Cisco Small Business Switches Secure Shell Certificate Authentication Bypass
Vulnerability
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
CVE-2019-1859
CWE-285
CVSS Score:
7.2 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Summary
o
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
authentication.
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:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-scbv
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 1.4.10.6 Small Business 300 Series Managed Switches
Small Business 500 Series Managed Switches
250 Series Smart Switches
Prior to 2.5.0.78 350 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.
Workarounds
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
default.
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:
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
Cisco fixed this vulnerability in the following software releases.
Cisco Software Release Cisco Switches
Small Business 200 Series Smart Switches
1.4.10.6 Small Business 300 Series Managed Switches
Small Business 500 Series Managed Switches
250 Series Smart Switches
2.5.0.78 350 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
page.
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.
Source
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.
URL
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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