Cisco Security Advisory
Click Icon to Copy Verbose Score
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
-
A vulnerability in the Secure Shell (SSH) subsystem of Cisco Small Business Managed Switches software could allow an authenticated, remote attacker to cause a reload of the affected switch, resulting in a denial of service (DoS) condition.
The vulnerability is due to improper processing of SSH connections. An attacker could exploit this vulnerability by logging in to an affected switch via SSH and sending a malicious SSH message.
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-20170920-sbms
-
Vulnerable Products
This vulnerability affects the following Cisco products when SSH is enabled:
- Cisco Small Business 300 Series Managed Switches
- Cisco Small Business 500 Series Stackable Managed Switches
- Cisco 350 Series Managed Switches
- Cisco 350X Series Stackable Managed Switches
- Cisco 550X Series Stackable Managed Switches
- Cisco ESW2 Series Advanced Switches
- SSH is not enabled on the affected platforms by default. To verify if SSH is enabled, navigate to Security > TCP/UDP Services and look for the Enabled checkbox next to SSH Service.
- This issue is exploitable only with SSH User Authentication by Password enabled under Security > SSH Server > SSH User Authentication. (In 2.x software, this option is visible in Advanced display mode only.)
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
- Cisco Small Business 200 Series Smart Switches
- Cisco Small Business 220 Series Smart Plus Switches
- Cisco 250 Series Smart Switches
-
There are no workarounds that address 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:
http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.htmlAdditionally, 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 upgrade 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:
http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.htmlCustomers 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 Product
First Fixed Release for This Vulnerability
Small Business 300 Series Managed Switches
1.4.8.06
Small Business 500 Series Stackable Managed Switches
ESW2 Series Advanced Switches
350 Series Managed Switches
2.3.0.130
350X Series Stackable Managed Switches
550X Series Stackable Managed Switches
The software can be downloaded from the Software Center on Cisco.com by navigating to Downloads Home > Products > Switches > LAN Switches - Small Business and selecting the respective model.
-
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.
-
This vulnerability was reported to Cisco by external researcher Alessandro Celestra of TLogos.
-
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.
-
Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2017-September-20
-
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.