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
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
This vulnerability affects the following Cisco products running the software releases shown in the left column.
| Cisco Software Release | Cisco Switches |
|---|---|
| Prior to 1.4.10.6 |
Small Business 200 Series Smart Switches Small Business 300 Series Managed Switches Small Business 500 Series Managed Switches |
| Prior to 2.5.0.78 |
250 Series Smart Switches 350 Series Managed Switches 350X Series Managed Switches 550X Series Stackable Managed Switches |
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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 |
|---|---|
| 1.4.10.6 |
Small Business 200 Series Smart Switches Small Business 300 Series Managed Switches Small Business 500 Series Managed Switches |
| 2.5.0.78 |
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:
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.
Cisco would like to thank Katie Sexton and Jimi Sebree of Tenable Research for reporting these vulnerabilities.
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 |
|---|---|---|---|---|
| 1.0 | Initial public release. | - | Final | 2019-May-01 |
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