7 Unsecured Services

7.3 Global Discovery Server Security

7.3.1 Overview

The Global Discovery Server (GDS) is a special OPC UA Server that provides Discovery services for a plant or entire system. In addition it can provide certificate management functionality (See OPC 10000-12)
There are multiple methods of accessing a GDS:
- Servers can register with the Discovery Server
- Clients can query the GDS for available Servers
- Clients can pull certificates from the GDS
- Servers can pull certificates from the GDS
- The GDS can push certificates to a Server
- The GDS can access other discovery Servers to build a list of available Servers. Several types of threats need to be discussed with regard to the available access methods:
Threats where a rogue GDS is in a system. Threats against the GDS, including the presence of rogue Clients or Servers Threats against the certificate management functionality provided by a GDS.