Threat Modeling of a Smart Grid Secondary Substation

Filip Holik,Lars Halvdan Flå,Martin Gilje Jaatun,Sule Yildirim Yayilgan,Jørn Foros

doi:10.3390/electronics11060850

Filip Holik, Lars Halvdan Flå + Show 3 more

Open Access

https://doi.org/10.3390/electronics11060850

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Abstract

A full smart grid implementation requires the digitization of all parts of the smart grid infrastructure, including secondary electrical substations. Unfortunately, this introduces new security threats, which were not apparent before. This article uses a Smart Grid Threat Modeling Template implementing the STRIDE model to create a threat model of a digital secondary substation and its communication with the control center. Threats are classified by priority and need for further investigation. The tool was compared with a CORAS analysis, and was determined to be more time efficient. Denial of service (DoS) threats were classified as the most critical, and they were further evaluated in a precise simulation model created for this purpose. This model combines simulation with emulated communication, and enables verification of threat likelihoods and impacts. The results show that even publicly available tools can be easily used to disrupt grid communication and potentially cause loss of the entire grid’s observability and controllability.

Highlights

The results show that even publicly available tools can be used to disrupt grid communication and potentially cause loss of the entire grid’s observability and controllability
Secondary substations are less secure by nature—they are located in accessible areas, they are not protected by fences, and they are not monitored by a manned crew
The STRIDE model was created for use in threat modeling of software, and it is normally applied at a lower abstraction level than is the case with the Smart Grid Threat Modeling Template (SG-TMT)

Summary

Introduction

Grid digitization started with primary substations, which transform high voltage in to medium voltage and serve a large number of supply points. On the other hand, serving smaller areas results in having a significantly higher number of secondary substations when compared with primary substations This makes their digitization process more demanding. Secondary substations are less secure by nature—they are located in accessible areas (neighborhoods), they are not protected by fences, and they are not monitored by a manned crew. They are, integrated into the grid’s communication network in the same way as primary substations. They are attractive entry points to launch an attack on the entire grid network

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