|2016-09-20||OPC||Moxa Active OPC Server ||Zhou Yu||N/A||2016-5793||N/A||N/A||N/A|
# Moxa Active OPC Server Unquoted Service Path Escalation Vulnerability
Independent researcher Zhou Yu has identified an unquoted service path escalation vulnerability in Moxa’s Active OPC Server application. Moxa has produced a new version to mitigate this vulnerability. Zhou Yu has tested the new version to validate that it resolves the vulnerability.
### AFFECTED PRODUCTS
Moxa reports that the vulnerability affects the following product:
Active OPC Server versions older than Version 2.4.19
Successful exploitation of this vulnerability could potentially allow an authorized but nonprivileged local user to execute arbitrary code with elevated privileges on the system.
Impact to individual organizations depends on many factors that are unique to each organization. NCCIC/ICS-CERT recommends that organizations evaluate the impact of this vulnerability based on their operational environment, architecture, and product implementation.
Moxa is a Taiwan-based company that maintains offices in several countries around the world, including the US, UK, India, Germany, France, China, Russia, and Brazil.
The affected product, Active OPC Server, is a software package that operates as an OPC driver for an HMI or SCADA system. According to Moxa, Active OPC Server is deployed across several sectors including Commercial Facilities, Critical Manufacturing, Energy, Transportation Systems, and others. Moxa estimates that this product is used primarily in the United States and Europe with a small percentage in Asia.
### VULNERABILITY CHARACTERIZATION
# VULNERABILITY OVERVIEW
UNQUOTED SERVICE PATH
This vulnerability allows an authorized individual with access to a file system to possibly escalate privileges by inserting arbitrary code into the unquoted service path.
CVE-2016-5793 has been assigned to this vulnerability. A CVSS v3 base score of 8.8 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).
### VULNERABILITY DETAILS
This vulnerability is not exploitable remotely and cannot be exploited without local authorized user credentials.
# EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
An attacker with a low skill would be able to exploit this vulnerability.
Moxa recommends replacing existing Active OPC Server installations with the new software MX-AOPC UA server. Active OPC Server is nearing end of life by the end of 2016, and no further updates will be issued.
For existing Active OPC installations, Moxa suggests upgrading to Active OPC Server Version 2.4.19.
If more information about patching is needed, Moxa recommends contacting the Moxa Technical Support team or by visiting the Moxa technical support web page at: