Georgios Zachos

Mr. Georgios Zachos

Faculty of Engineering and Science, University of Greenwich, Chatham Maritime ME4 4TB, UK
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orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 March 2022 in Sensors
Verified
Journal Article
Open access
PDF file
FPFilippos Pelekoudas-Oikonomou
Filippos Pelekoudas-Oikonomou
GZGeorgios Zachos
Georgios Zachos
Maria PapaioannouMaria Papaioannou
Maria Papaioannou
MRMarcus de Ree
Marcus de Ree
José RibeiroJosé Ribeiro
José Ribeiro
JRJonathan Rodriguez
Jonathan Rodriguez
Despite the significant benefits that the rise of Internet of Medical Things (IoMT) can bring into citizens’ quality of life by enabling IoMT-based healthcare monitoring systems, there is an urgent need for novel security mechanisms to address the pressing security challenges of IoMT edge networks in an effective and efficient manner before they gain the trust of all involved stakeholders and reach their full potential in the market of next generation IoMT-based healthcare monitoring systems. In this context, blockchain technology has been foreseen by the industry and research community as a disruptive technology that can be integrated into novel security solutions for IoMT edge networks, as it can play a significant role in securing IoMT devices and resisting unauthorized access during data transmission (i.e., tamper-proof transmission of medical data). However, despite the fact that several blockchain-based security mechanisms have already been proposed in the literature for different types of IoT edge networks, there is a lack of blockchain-based security mechanisms for IoMT edge networks, and thus more effort is required to be put on the design and development of security mechanisms relying on blockchain technology for such networks. Towards this direction, the first step is the comprehensive understanding of the following two types of blockchain-based security mechanisms: (a) the very few existing ones specifically designed for IoMT edge networks, and (b) those designed for other types of IoT networks but could be possibly adopted in IoMT edge networks due to similar capabilities and technical characteristics. Therefore, in this paper, we review the state-of-the-art of the above two types of blockchain-based security mechanisms in order to provide a foundation for organizing research efforts towards the design and development of reliable blockchain-based countermeasures, addressing the pressing security challenges of IoMT edge networks in an effective and efficient manner.

20 October 2021 in Electronics
Verified
Journal Article
Open access
PDF file
GZGeorgios Zachos
Georgios Zachos
IEIsmael Essop
Ismael Essop
Georgios MantasGeorgios Mantas
Georgios Mantas
KPKyriakos Porfyrakis
Kyriakos Porfyrakis
José RibeiroJosé Ribeiro
José Ribeiro
JRJonathan Rodriguez
Jonathan Rodriguez
Over the past few years, the healthcare sector is being transformed due to the rise of the Internet of Things (IoT) and the introduction of the Internet of Medical Things (IoMT) technology, whose purpose is the improvement of the patient’s quality of life. Nevertheless, the heterogenous and resource-constrained characteristics of IoMT networks make them vulnerable to a wide range of threats. Thus, novel security mechanisms, such as accurate and efficient anomaly-based intrusion detection systems (AIDSs), considering the inherent limitations of the IoMT networks, need to be developed before IoMT networks reach their full potential in the market. Towards this direction, in this paper, we propose an efficient and effective anomaly-based intrusion detection system (AIDS) for IoMT networks. The proposed AIDS aims to leverage host-based and network-based techniques to reliably collect log files from the IoMT devices and the gateway, as well as traffic from the IoMT edge network, while taking into consideration the computational cost. The proposed AIDS is to rely on machine learning (ML) techniques, considering the computation overhead, in order to detect abnormalities in the collected data and thus identify malicious incidents in the IoMT network. A set of six popular ML algorithms was tested and evaluated for anomaly detection in the proposed AIDS, and the evaluation results showed which of them are the most suitable.

23 February 2021 in Sensors
Verified
Journal Article
Open access
PDF file
IEIsmael Essop
Ismael Essop
José RibeiroJosé Ribeiro
José Ribeiro
Maria PapaioannouMaria Papaioannou
Maria Papaioannou
GZGeorgios Zachos
Georgios Zachos
Georgios MantasGeorgios Mantas
Georgios Mantas
JRJonathan Rodriguez
Jonathan Rodriguez
Over the past few years, we have witnessed the emergence of Internet of Things (IoT) and Industrial IoT networks that bring significant benefits to citizens, society, and industry. However, their heterogeneous and resource-constrained nature makes them vulnerable to a wide range of threats. Therefore, there is an urgent need for novel security mechanisms such as accurate and efficient anomaly-based intrusion detection systems (AIDSs) to be developed before these networks reach their full potential. Nevertheless, there is a lack of up-to-date, representative, and well-structured IoT/IIoT-specific datasets which are publicly available and constitute benchmark datasets for training and evaluating machine learning models used in AIDSs for IoT/IIoT networks. Contribution to filling this research gap is the main target of our recent research work and thus, we focus on the generation of new labelled IoT/IIoT-specific datasets by utilising the Cooja simulator. To the best of our knowledge, this is the first time that the Cooja simulator is used, in a systematic way, to generate comprehensive IoT/IIoT datasets. In this paper, we present the approach that we followed to generate an initial set of benign and malicious IoT/IIoT datasets. The generated IIoT-specific information was captured from the Contiki plugin “powertrace” and the Cooja tool “Radio messages”.

3 March 2025 in IEEE Access
Verified
Journal Article
Open access
GZGeorgios Zachos
Georgios Zachos
Georgios MantasGeorgios Mantas
Georgios Mantas
KPKyriakos Porfyrakis
Kyriakos Porfyrakis
JBJoaquim Manuel Camões Sobral de Bastos
Joaquim Manuel Camões Sobral de Bastos
JRJonathan Rodriguez
Jonathan Rodriguez
The Internet of Things has transformed the healthcare sector through the introduction of the Internet of Medical Things (IoMT) technology. However, IoMT networks remain vulnerable to a wide range of threats due to their resource-constrained characteristics and heterogeneity. Therefore, novel security mechanisms such as accurate and efficient Anomaly-based Intrusion Detection Systems (AIDSs), taking into consideration the inherent limitations of the IoMT networks, are necessary to be developed before IoMT networks reach their full potential in the market. This paper is an extension of our previous works and presents a new and refined design of a hybrid AIDS for IoMT networks. Furthermore, we provide implementation details on Raspberry Pi devices and performance evaluation results that demonstrate the efficacy of our approach. For its detection purposes, the AIDS employs Novelty detection and Outlier detection algorithms as these types of ML algorithms can detect both known and unknown types of attacks. Then, we tuned the hyperparameters of various Novelty Detection and Outlier Detection ML algorithms and evaluated their performance. Afterwards, the best performing ML algorithms (i.e., OCSVM, LOF, G_KDE, PW_KDE, B_GMM, MCD and IsoForest) are selected to be integrated into the AIDS deployed on an IoT/IoMT testbed. In addition, we evaluated the performance of the deployed AIDS during runtime, and the runtime evaluation results indicate: (i) a strong detection performance for some of the integrated ML algorithms, and (ii) a low computational cost (i.e., less than 1 % cpu usage) of the AIDS for all integrated ML algorithms..

1 April 2022 in IEEE Access
Verified
Journal Article
Open access
Maria PapaioannouMaria Papaioannou
Maria Papaioannou
GZGeorgios Zachos
Georgios Zachos
IEIsmael Essop
Ismael Essop
Georgios MantasGeorgios Mantas
Georgios Mantas
JRJonathan Rodriguez
Jonathan Rodriguez
Nowadays the critical sector of transport becomes progressively more dependent on digital technologies to perform essential activities and develop novel efficient transport services and infrastructure to empower economic and social cohesion exploiting the economic strengths of the European Union (EU). However, although the continuously increasing number of visitors, entering the EU through land-border crossing points or seaports, brings immense economic value, novel border control solutions, such as mobile devices for passenger identification for land/sea border control, are essential to precisely identify passengers “on the fly” ensuring their comfort. Nevertheless, these devices are expected to handle highly confidential personal data and thus, it is very likely to become an attractive target to malicious actors. Therefore, to ensure high level of device security without interrupting border control activities, strong secure and usable user authentication mechanisms are required. Towards this direction, we, firstly, discuss risk-based and adaptive authentication for mobile devices as a suitable approach to deal with the security vs. usability challenge and a novel risk-based adaptive user authentication mechanism is proposed to address this challenge. Afterwards, a set of popular Machine Learning (ML) classification algorithms for risk-based authentication was tested and evaluated on the HuMIdb (Human Mobile Interaction database) dataset to identify the most appropriate ones for the proposed mechanism. The evaluation results demonstrated impact of overfitting (i.e., accuracy: 1,0000) and therefore, we considered novelty detection algorithms to overcome this challenge and demonstrate high performance. To the best of our knowledge, this is the first time that novelty detection algorithms have been considered for risk-based adaptive user authentication showing promising results (OneClassSVM 0,9536, LOF 0,9740, KNN_average 0,9998).

17 February 2025 in Sensors
Verified
Journal Article
Open access
PDF file
GZGeorgios Zachos
Georgios Zachos
Georgios MantasGeorgios Mantas
Georgios Mantas
KPKyriakos Porfyrakis
Kyriakos Porfyrakis
JRJonathan Rodriguez
Jonathan Rodriguez
Internet of Medical Things (IoMT) technology has emerged from the introduction of the Internet of Things in the healthcare sector. However, the resource-constrained characteristics and heterogeneity of IoMT networks make these networks susceptible to various types of threats. Thus, it is necessary to develop novel security solutions (e.g., efficient and accurate Anomaly-based Intrusion Detection Systems), considering the inherent limitations of IoMT networks, before these networks reach their full potential in the market. In this paper, we propose an AIDS specifically designed for resource-constrained devices within IoMT networks. The proposed lightweight AIDS leverages novelty detection and outlier detection algorithms instead of conventional classification algorithms to achieve (a) enhanced detection performance against both known and unknown attack patterns and (b) minimal computational costs.