Modeling the propagation and defense study of internet malicious information

 Dr. Wen\u27s research includes modelling the propagation dynamics of malicious information, exposing the most influential people and source identification of epidemics in social networks. His research is beneficial to both academia and industry in the field of Internet social networks

Rumor source identification in complex networks

This thesis conducts an in-depth study on rumor spreading process through a complex network, with the objective to identify the source(s) of the rumor. This work is of fundamental importance for a secure network.<br /

Protection against Contagion in Complex Networks

In real-world complex networks, harmful spreads, commonly known as contagions, are common and can potentially lead to catastrophic events if uncontrolled. Some examples include pandemics, network attacks on crucial infrastructure systems, and the propagation of misinformation or radical ideas. Thus, it is critical to study the protective measures that inhibit or eliminate contagion in these networks. This is known as the network protection problem. The network protection problem investigates the most efficient graph manipulations (e.g., node and/or edge removal or addition) to protect a certain set of nodes known as critical nodes. There are two types of critical nodes: (1) predefined, based on their importance to the functionality of the network; (2) unknown, whose importance depends on their location in the network structure. For both of these groups and with no assumption on the contagion dynamics, I address three major shortcomings in the current network protection research: namely, scalability, imprecise evaluation metric, and assumption on global graph knowledge. First, to address the scalability issue, I show that local community information affects contagion paths through characteristic path length. The relationship between the two suggests that, instead of global network manipulations, we can disrupt the contagion paths by manipulating the local community of critical nodes. Next, I study network protection of predefined critical nodes against targeted contagion attacks with access to partial network information only. I propose the CoVerD protection algorithm that is fast and successfully increases the attacker’s effort for reaching the target nodes by 3 to 10 times compared to the next best-performing benchmark. Finally, I study the more sophisticated problem of protecting unknown critical nodes in the context of biological contagions, with partial and no knowledge of network structure. In the presence of partial network information, I show that strategies based on immediate neighborhood information give the best trade-off between performance and cost. In the presence of no network information, I propose a dynamic algorithm, ComMit, that works within a limited budget and enforces bursts of short-term restriction on small communities instead of long-term isolation of unaffected individuals. In comparison to baselines, ComMit reduces the peak of infection by 73% and shortens the duration of infection by 90%, even for persistent spreads

Influence Analysis towards Big Social Data

Large scale social data from online social networks, instant messaging applications, and wearable devices have seen an exponential growth in a number of users and activities recently. The rapid proliferation of social data provides rich information and infinite possibilities for us to understand and analyze the complex inherent mechanism which governs the evolution of the new technology age. Influence, as a natural product of information diffusion (or propagation), which represents the change in an individual’s thoughts, attitudes, and behaviors resulting from interaction with others, is one of the fundamental processes in social worlds. Therefore, influence analysis occupies a very prominent place in social related data analysis, theory, model, and algorithms. In this dissertation, we study the influence analysis under the scenario of big social data. Firstly, we investigate the uncertainty of influence relationship among the social network. A novel sampling scheme is proposed which enables the development of an efficient algorithm to measure uncertainty. Considering the practicality of neighborhood relationship in real social data, a framework is introduced to transform the uncertain networks into deterministic weight networks where the weight on edges can be measured as Jaccard-like index. Secondly, focusing on the dynamic of social data, a practical framework is proposed by only probing partial communities to explore the real changes of a social network data. Our probing framework minimizes the possible difference between the observed topology and the actual network through several representative communities. We also propose an algorithm that takes full advantage of our divide-and-conquer strategy which reduces the computational overhead. Thirdly, if let the number of users who are influenced be the depth of propagation and the area covered by influenced users be the breadth, most of the research results are only focused on the influence depth instead of the influence breadth. Timeliness, acceptance ratio, and breadth are three important factors that significantly affect the result of influence maximization in reality, but they are neglected by researchers in most of time. To fill the gap, a novel algorithm that incorporates time delay for timeliness, opportunistic selection for acceptance ratio, and broad diffusion for influence breadth has been investigated. In our model, the breadth of influence is measured by the number of covered communities, and the tradeoff between depth and breadth of influence could be balanced by a specific parameter. Furthermore, the problem of privacy preserved influence maximization in both physical location network and online social network was addressed. We merge both the sensed location information collected from cyber-physical world and relationship information gathered from online social network into a unified framework with a comprehensive model. Then we propose the resolution for influence maximization problem with an efficient algorithm. At the same time, a privacy-preserving mechanism are proposed to protect the cyber physical location and link information from the application aspect. Last but not least, to address the challenge of large-scale data, we take the lead in designing an efficient influence maximization framework based on two new models which incorporate the dynamism of networks with consideration of time constraint during the influence spreading process in practice. All proposed problems and models of influence analysis have been empirically studied and verified by different, large-scale, real-world social data in this dissertation

Fake News in the era of online intentional misinformation ; a review of existing approaches

Διπλωματική εργασία--Πανεπιστήμιο Μακεδονίας, Θεσσαλονίκη, 2019.Fake news is probably one of the most discussed issues of the past years. The term has acquired greater legitimacy after being named the word of the year by Collins Dictionary, following what the dictionary called its “ubiquitous presence” over the year 2017. However, the fake news issue has not been yet deeply researched. Therefore, in this thesis, definitions by the literature about the term “fake news” are gathered and through them, specific characteristics and criteria are extracted in order to verify the exact elements of false news and intentional misinformation in general. This study aims to identify eventually as thoroughly as possible what fake news is and what is not. For that purpose, through qualitative research, the total features of the term are exhibited and analyzed concluding in the classification of characteristics most of the fake news incidents present. Following the proposed feature identification is examined through specific fake news case studies. Finally, after understanding deeper and verifying specific characteristics that appear on the nature of fake news detection and mitigation actions are proposed, demonstrating the need for technological development on the issue and educational evolution on digital skills of the public, accomplishing an inclusive review of a less studied term, such as the fake news. At last conclusions are presented leading to the main remark of the current thesis, namely the need for further quantitative and statistical research as much as deeper theoretical study, to better decipher the issue of fake news and thus resolve it

Image Based Attack and Protection on Secure-Aware Deep Learning

In the era of Deep Learning, users are enjoying remarkably based on image-related services from various providers. However, many security issues also arise along with the ubiquitous usage of image-related deep learning. Nowadays, people rely on image-related deep learning in work and business, thus there are more entries for attackers to wreck the image-related deep learning system. Although many works have been published for defending various attacks, lots of studies have shown that the defense cannot be perfect. In this thesis, one-pixel attack, a kind of extremely concealed attacking method toward deep learning, is analyzed first. Two novel detection methods are proposed for detecting the one-pixel attack. Considering that image tempering mostly happens in image sharing through an unreliable way, next, this dissertation extends the detection against single attack method to a platform for higher level protection. We propose a novel smart contract based image sharing system. The system keeps full track of the shared images and any potential alteration to images will be notified to users. From extensive experiment results, it is observed that the system can effectively detect the changes on the image server even in the circumstance that the attacker erases all the traces from the image-sharing server. Finally, we focus on the attack targeting blockchain-enhanced deep learning. Although blockchain-enhanced federated learning can defend against many attack methods that purely crack the deep learning part, it is still vulnerable to combined attack. A novel attack method that combines attacks on PoS blockchain and attacks on federated learning is proposed. The proposed attack method can bypass the protection from blockchain and poison federated learning. Real experiments are performed to evaluate the proposed methods

Off and Online Journalism and Corruption

This book provides a new theoretical framework of determinants that interact together in five hierarchical levels to restrain or produce corruption. The theory suggests a multilevel analysis that tests hypotheses regarding the relations of journalism and corruption within each level and across levels in international comparative research designs. Corruption as the abuse of power for private gain is built into the journalistic, economic, political, and cultural structures of any society and is affected by its interaction within the international system. The important questions of how differences in corruption across countries can be explained or what makes it more or less in a particular society and how press freedom and social media contribute to the fight against corruption are still unanswered. This book represents a significant contribution on the way to answer these critical questions. It discusses a variety of journalism-corruption experiences that provide a wealth of results and analyses. The cases it examines extend from Cuba to Algeria, India, Saudi Arabia, Sub-Saharan African, Gulf Cooperation Countries, Arab World, and Japan. The primary contribution of this book is both theoretical and empirical. Its details as well as the general theoretical frameworks make it a useful book for scholars, academics, undergraduate and graduate students, journalists, and policy makers

First steps in the study of cyber-psycho-cognitive operations

Dissertação (mestrado)—Universidade de Brasília, Instituto de Relações Internacionais, Programa de Pós-Graduação em Relações Internacionais, 2019.O presente trabalho é uma análise dos mecanismos informáticos e tecno-comunicacionais envolvidos na articulação de mundos da vida orientados estrategicamente para estimular, prever ou minar o desenvolvimento das condições psico-cognitivas adequadas para a construção e sustento da legitimidade racional de uma autoridade ou ação política. A aplicação de instrumentos “arqueológicos” Foucauldianos ao estudo das narrativas políticas que engendraram e surgiram de “Russiagate” permitiu situar a teoria num contexto histórico e validar a premissa da convergência e incorporação de tendências de agendamento comuns e de práticas típicas de operações psicológicas tradicionais. Contudo, os efeitos tanto da disponibilidade comercial das TICs com capacidade de “deep learning”, quanto da estruturação baseada em conhecimento permitida pela ubiquidade e centralidade econômica dessas tecnologias, tornam o conjunto de mecanismos analisados num fenômeno que merece uma conceptualização e marco investigativo únicos. A obra é uma contribuição a esse empreendimento.This is an analysis of the ICT-based mechanisms involved in the articulation of lifeworlds that are strategically oriented to foster, prevent or undermine the development of psycho-cognitive conditions adequate for the construction or sustainability of an authority’s or a political action’s rational legitimacy. While grounding theory to a historical context, the application of Foucauldian “archeological” instruments to the study of the political narratives giving birth and springing from “Russiagate” also served to validate the premised convergence and incorporation of common agenda-setting trends and practices typical of traditional psychological operations. However, the effects of both the commercial availability of deep-learning ICTs and the cognition-based structuration afforded by their ubiquity and economic centrality set this “dispositif” apart, thereby deserving a unique conceptualization and research framework. This study is a contribution to such endeavor