A Hybrid Access Control Model for CIM-Based SCADA System

Insider attack is one of the most dangerous threats for the security of a critical infrastructure (CI). An insider attack occurs when an authorized operator misuses his/her permissions in order to perform malicious operations in the CI. Providing too many permissions for an operator may backfire when the operator abuses his/her privileges, either intentional or unintentional. Therefore, an access control model is required to provide necessary permissions in order to prevent malicious operations. In this paper, a hybrid access control model (HAC) has been proposed for CI applications which are monitored and controlled by a CIM (IEC-61970-301 common information model)-based supervisory control and data acquisition system. The proposed HAC is an extension of the mandatory and role-based access control models. In the proposed model, the permissions of an operator will be determined according to the predefined types of responsibilities, grid statuses, activation times of roles, security levels, and their periods of validity. A colored Petri-net is employed to simulate and illustrate the effectiveness of the proposed HAC.