Moxa Issue on Discontinued Product

Tuesday, May 31, 2016 @ 03:05 PM gHale


Since Moxa discontinued the specific product, the company created instructions to reduce exposure to a firmware overwrite vulnerability in its UC 7408-LX-Plus device, according to a report on ICS-CERT.

This vulnerability, reported to ICS-CERT by a third party, is remotely exploitable.

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UC-7408 LX-Plus all versions suffer from the issue.

A firmware overwrite ended up used that is neither recoverable in the field or by the manufacturer, necessitating the replacement of the device.

Moxa is a Taiwan-based company that maintains offices in several countries around the world, including the U.S., UK, India, Germany, France, China, Russia, and Brazil.

The affected product, UC-7408-LX-Plus, is an embedded computer. These computers end up deployed across several sectors, including chemical, commercial facilities, critical manufacturing, emergency services, energy, food and agriculture, government facilities, and water and wastewater systems. Moxa said this product see use globally but concentrated in the U.S., Europe, Chile, Argentina, Peru, Columbia, and Taiwan, with 50 to 60 percent of all sales in the U.S.

The firmware overwrite is neither recoverable in the field or by the manufacturer, necessitating the replacement of the device.

CVE-2016-4500 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 5.8.

No known public exploits specifically target this vulnerability. In addition, crafting a working exploit for this vulnerability would be difficult. Root level access is necessary for this exploit. This decreases the likelihood of a successful exploit.

Moxa recommends the following suggestions to reduce the risk of unauthorized access to UC 7408-LX-Plus:
• Strengthen authentication requirements
1. Change passwords for administrative users periodically
2. Use the stronger password. Ex: mixed with upper and lower case character and number
3. Disable or delete unused profiles from system
4. Provide login authentication at all access portals before accessing this device ex: console, ssh, web
5. Disable unnecessary services
6. Enable system log for monitoring
7. Log unsuccessful login attempts
8. Auto log out from ssh or telnet console after a period of inactivity

• Increase access control
1. Restrict mobile code download and execution
2. Limit the number of concurrent sessions. Ex: SSH is limited to 5
3. Log the access control information with timestamps for audit purpose

• Enhance data integrity
1. Use secure transmission protocol, SSH, VPN, HTTPS, etc., to protect integrity of information

• Enhance data confidentiality
1. Remove the shared data if the shared resource is not used

• Restrict data flow
1. Enable firewall function for deny all accept exception rule