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Abstract

Published at: Transactions on Emerging Telecommunications Technologies, 35(5). (2024). https://doi.org/10.1002/ett.4986

Recent device-level cyber-attacks have targeted IoT critical applications in power distribution systems integrated with the Internet communications infrastructure. These systems utilize group domain of interpretation (GDOI) as designated by International Electrotechnical Commission (IEC) power utility standards IEC 61850 and IEC 62351. However, GDOI cannot protect against novel threats, such as IoT device-level attacks that can modify device firmware and configuration files to create command and control malicious communication. As a consequence, the attacks can compromise substations with potentially catastrophic consequences. With this in mind, this article proposes a permissioned/private blockchain-based authentication framework that provides a solution to current security threats such as the IoT device-level attacks. Our work improves the GDOI protocol applied in critical IoT applications by achieving decentralized and distributed device authentication. The security of our proposal is demonstrated against known attacks as well as through formal mechanisms via the joint use of the AVISPA and SPAN tools. The proposed approach adds negligible authentication latency, thus ensuring appropriate scalability as the number of nodes increases.

Introduction

Recent advances in Internet of Things (IoT) and 5G technologies have impacted day to day electrical power grids opera-tions. As such, we are in the age of intelligent power distribution, management and consumption. Thus, modern electricalpower systems are considered cyber-physical systems that incorporate sensing, data processing, and real-time monitor-ing with remote access.1 The modern electrical grids have moved from old and closed communication environments tomore open ones in particular with its integration with internet infrastructure.2 With this, new threats have risen due tothe integration of the closed and controlled communications with external communication networks. 3–5There are many security standards used in the electrical grid’s domain as well as traditional cybersecurity solutionssuch as intrusion detection systems and firewalls, which play a crucial role in the security of electrical grids.6 However,recent attacks 7,8,9 against these systems provide insights into how the proposed standards and traditional cybersecu-rity solutions fall short in dealing with the latest threat landscape, particularly the IoT device-level attacks that targetmodifying device firmware to create command and control communication with malicious actors. It is an undeniablefact that IoT has changed the traditional view of grid security. If the smart grid is disrupted or sabotaged, it will have severe consequences on people’s welfare and the stability of the economy. Established security mechanisms fall short inprotecting the intelligent grid against IoT device-level attacks.10Nevertheless, there are adequate guidelines and security solutions in the power distribution arena. In terms of estab-lishing device Security Associations (SA) and secure update and distribution of secret keys, the Group Domain OfInterpretation 11 (GDOI) protocol is recommended by the official power utility standards.12 The main focus of GDOI isto ensure secure communications during distribution and update of security policies. However, if, for any reason, thedevice gets compromised, an attacker can gain access to the Group Security Association (GSA) keys stored in memoryand therefore gain access to all of the group communications.The assumptions in designing old security mechanisms no longer hold in new communication environments, as wenow must consider external and remote security threats. 13 Consequently, a new wave of cyber-attacks, such as deviceidentity theft, the creation of bots, and remote code execution, have emerged. They allow malicious attackers to takecontrol of Intelligent Electronic Devices (IEDs) and compromise the operation of critical applications in power sub-stations.8,9 Compromised IEDs may have different roles in the application context, from collecting and sending statusreports to supporting the execution of system-level commands. Therefore, the impact of such compromises can be, inmany situations, catastrophic. 14The recommended security standards, such as IEC 6185012 and IEC 62351,15 recommend GDOI protocol. Technicallythe focus is more network-oriented and therefore, the aim is to secure communications while assuming that IEDs arenot compromised. However, most recent cyber-attacks can be categorized as device-level attacks, such as identity theft,the introduction of fake nodes, and malware to create bots to compromise IEDs. 16 This means that emerging securitythreats can evade existing protection mechanisms, compromise devices, capture security keys, or establish commandand control communication with bad actors. This work addresses the challenges of compromised devices by providingscalable authentication and corresponding device integrity mechanisms, essential to protect smart grids from device-levelattacks, while maintaining compatibility with current standards used by the industry.Therefore, we improve the smart grid security in twofold: first contribution is scalable distributed device authenti-cation leveraging blockchain and smart contracts for Phase I of the GDOI protocol. Phase 1 in GDOI implements peerauthentication procedure in a centralized fashion. Our approach does not require certificates and is decentralized, thusavoiding the centralized management of certificates by a trusted Certificate Authority (CA). It also eliminates the singlepoint of failure during the peer authentication procedure while allowing scalable authentication of more devices takinginto account authentication delays, throughput and CPU consumption. In our second contribution, we introduce a deviceintegrity check to improve Phase II of the GDOI protocol. The motivation for our second contribution is related to thecurrent GDOI Phase II which does not have mechanisms to protect devices against device-level attacks such as firmwaremodification and alteration of configuration files. Thus, opening the door to IoT device-level attacks.While several researchers have provided improvement of smart grid security through improving GDOI and even intro-ducing new protocols by using blockchain. To the best of our knowledge there is no article discussing the importance ofscalable authentication in smart grid IEDs as well as the use of blockchain technology to achieve this while improvingthe GDOI protocol. In this paper, we not only present state-of-the-art literature on GDOI use in smart grid but also, weidentify and improve the GDOI protocol by scalable authentication in phase I and integrity protection in phase II.The remainder of the article is organized as follows: Section 2 describes the relevant works. In Section 3, the articleprovides background on key concepts such as blockchain and smart contracts, distributed authentication, and the GDOIprotocol. Section 4 presents our system model, attacker model, and proposed solution. In Section 5, the article presents theperformance evaluation of our solution, with a security analysis in Section 6. Finally, Section 6 describes our conclusionsand future research directions.

Conclusions and Future Work

This article addresses some of the security challenges of the widely used GDOI protocol. Our scheme introduces ablockchain device authentication mechanism in GDOI Phase I to achieve peer authentication as described by the GDOIstandard. This is allowed because GDOI is extensible, and new authentication approaches can be added to the pro-tocol. Therefore, the proposed authentication approach is compatible with the standard. We also proposed adding adevice integrity check mechanism that improves the security of GDOI Phase II. The introduced mechanisms aim tocover the gap and achieve the device-level security needed to protect against the recent wave of cyber-attacks thatcan be categorized as device-level attacks that can hijack devices, which result in devices being compromised. Theexperimental results show that the proposed blockchain-based authentication management solution adds negligibleauthentication latency in the GDOI Phase I. Performance results also show a stable throughput and CPU utilizationwhile experimenting with a higher number of nodes. Our results show that blockchain-based security mechanisms pro-vide clear advantages to GDOI, such as device authentication, data privacy, and protection against cyber-attacks, whichoutweighs the negligible effects on system performance. A security assessment was performed against known attacksand through the use of the AVISPA formal methods, thus showing the evidence of the security of our scheme. Finally,the presented approach is not limited to smart grid environments and can be used with general IoT-related applica-tions. In future work, we aim to extend our scalability evaluations and perform experiments in real-world smart gridsubstation. We will also investigate and integrate Physical Unclonable Functions (PUFs) to achieve secure bootstrapand key generation.

Acknowledgement

This work is supported by the European Regional Development Fund (FEDER), through the Regional Operational Pro-gramme of Centre (CENTRO 2020) of the Portugal 2020 framework and FCT, Portugal under the MIT Portugal Program[Project SNOB-5G with Nr. 045929 (CENTRO-01-0247-FEDER-045929)].

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