Madeleine van der Bruggen’s research while affiliated with Leiden University and other places

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Publications (7)


Even “lurkers” download: The behavior and illegal activities of members on a child sexual exploitation TOR hidden service
  • Article

November 2022

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72 Reads

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4 Citations

Aggression and Violent Behavior

Madeleine van der Bruggen

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Inge van Balen

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Arthur van Bunningen

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[...]

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Karlene Clapp

Knowledge about online child sexual exploitation (CSE) offenders mostly remains limited to offender populations known by the criminal justice system. Because of its hidden and anonymous nature, knowledge on those offenders active on the Darkweb is especially scarce. For the current study, researchers had access to a unique dataset of member communication on a Darkweb CSE website, as well as members' virtual movements (or clicks) across the side, regardless of being verbally active or not. This offered a unique opportunity to establish behavioral patterns of members who were unaware that they were being observed. This paper summarizes the results of a descriptive analysis of the growth of member count, the frequency with which members were online, and detailed member behavior such as their activity on certain sub-forums and their downloading activity. Main findings include that although only 3.4 % of the members were communicatively active, the vast majority of 93.6 % of members downloaded CSE material. Results indicate that regardless of being verbally active, most members do engage with the site's content, and thus, effectively impact the CSE community. This has important implications for law enforcement practice, which will be discussed.


Analysis of topic popularity within a child sexual exploitation Tor hidden service

November 2022

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87 Reads

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4 Citations

Aggression and Violent Behavior

Knowledge about the online bulletin board communities dedicated to child sexual exploitation (CSE) located on the Darkweb (Tor) has generally been limited to those that investigate and prosecute individuals participating in those sites, as accessing them and viewing the abuse material is a crime. This leaves many of those in the CSE field without a scientifically validated foundation of the behaviors typically demonstrated by members of these CSE online communities. The following research empirically examines topic popularity of one Darkweb CSE Tor hidden service that was seized by a federal law enforcement agency. Analyses reveal that some topics tend to be viewed significantly more often, and descriptors about specific sexual acts and the ages of children portrayed in the thread titles correlate with the frequency of viewing, approving and downloading of that material. Implications of these findings for professionals working in the CSE field will be discussed.


Schematic representation of the effects of restructuring the longitudinal posting data for five hypothetical forum members.
Number of posts and number of unique posting members per month.
Percentual distribution of the total number of monthly posts across topic category.
Distribution of posts (December 2010 to December 2014).
Diversity of the total posting volume by total number of posts.

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Profiling Darkweb Child Sexual Exploitation Material Forum Members Using Longitudinal Posting History Data
  • Article
  • Publisher preview available

August 2022

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339 Reads

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19 Citations

Darkweb fora dedicated to the illegal exchange of child sexual exploitation material (CSEM) continue to thrive. Profiling forum members based on their communication patterns will increase our insights in the dynamics of online CSEM and may aid law enforcement to identify those members who are most influential and pose the highest risk. The current study uses data from a large English language Darkweb CSEM forum that was active between 2010 and 2014, containing over 400,000 posts. Posts were time stamped, categorized based on subforum topic, and linked to individual forum members by nickname. Group-based trajectory modeling was subsequently applied to derive forum member profiles based on members’ posting history. Analyses show that over the course of the observation period, overall activity levels—in terms of total number of posting members and the average number of posts per month per member—fluctuate substantially and that multiple developmental pathways—in terms of monthly patterns in the frequency of posts by individual members—can be distinguished. Theoretical and practical ramifications of these findings are discussed.

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Figure 1. PRISMA flow diagram of the systematic literature search.
Overview of Study Characteristics and Main Findings from Psychological Articles.
Trust and Relationship Development Among Users in Dark Web Child Sexual Exploitation and Abuse Networks: A Literature Review From a Psychological and Criminological Perspective

December 2021

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399 Reads

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19 Citations

Trauma Violence & Abuse

The increased potential and speed of the Internet has changed the nature of sexual crimes against children. It enables individuals with a sexual interest in children to meet, interact, and engage in illegal activities. The literature review presented here aims to provide an overview of the current knowledge and understanding of trust and relationship development among users of online networks that are dedicated to the sexual exploitation and abuse of children. A systematic search using six databases was conducted to identify relevant literature from a psychological and a criminological perspective. Twenty-one studies met the inclusion criteria that centered around the key aspects of the literature review’s research question, namely, (i) child sexual exploitation and abuse, (ii) Dark Web platforms, (iii) online forums and networks, and (iv) trust and relationship development. Our findings reveal that the engagement in interpersonal communication and interactions with like-minded others serves various functions, including validation, normalization, and support, as well as access to expert advice, information, and material. Dark Web networks are high-stake and risky environments, where users have to manage a continuous flow of threats, with information about others and their trustworthiness being limited. The establishment and maintenance of trust is of social and technical relevance, and users have to navigate a number of demands and commitments. Findings are discussed in relation to theoretical and practical implications, as well as directions for future research.


Overview of the analyzed case files
Child Sexual Exploitation Communities on the Darkweb: How Organized Are They?

May 2021

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2,081 Reads

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8 Citations

Because of the growing incidence and increasing technical sophistication of Darkweb child sexual exploitation (CSE), some have begun to label it as organized crime. By itself however, this label adds little to our understanding of the phenomenon. To gain a more detailed insight into the workings of Darkweb CSE, we apply the conceptual framework suggested by Von Lampe (Organized crime: Analyzing illegal activities, criminal structures and extra-legal governance. Sage, Thousand Oaks, CA, 2016a) and instead ask: how organized is CSE on the Darkweb? Six police investigation case files were systematically analyzed using methods akin to the Dutch Organized Crime Monitor, complemented with interviews with police officers and public prosecutors. While the barter of CSE material in itself is a deviant exchange, it is embedded in the social network provided by the forum environment. Darkweb CSE requires organization to the extent that running a forum involves a set of interlocking tasks, a certain level of technical sophistication, and continued effort to protect the forum from (outside) threats. We conclude that both the CSE crime and the criminals perpetrating it show clear signs of organization. CSE Darkweb fora constitute both associational and entrepreneurial structures that serve the social and criminal needs of their members. In the trust-based hierarchy of these networks, key players are able to exert some internal governance. Monetary profit, violence, and the desire to monopolize the market however, are largely absent. Detailed insight in the dynamics of Darkweb CSE interactions will contribute more to reducing the harm caused by these crimes than the mere application of a label.


A Crime Script Analysis of Child Sexual Exploitation Material Fora on the Darkweb

December 2020

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212 Reads

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27 Citations

Sexual Abuse A Journal of Research and Treatment

This study's aim is to contribute to the knowledge on the steps involved in child sexual exploitation material (CSEM) crimes committed in Darkweb CSEM communities. Due to the anonymous and illegal nature of these communities, academic research is scarce. This study provides a crime script analysis of member communication data from four CSEM Darkweb fora obtained by law enforcement. For cross-validation, suspect interviews from a relevant case file were analyzed. A step-by-step description of the crime process, starting with the preparations necessary to access Darkweb CSEM fora and ending with the postactivity behaviors of exiting the crime scene and preventing detection, is given, focusing on the casts, activities, probs, and personal and contextual requirements at each stage. The findings highlight the scope of the CSEM problem, as well as the influence the Darkweb has on the way the crime is committed. Suitable targets for law enforcement intervention are discussed.


Characterizing Key Players in Child Exploitation Networks on the Dark Net: Volume 2 Proceedings The 7th International Conference on Complex Networks and Their Applications COMPLEX NETWORKS 2018

January 2019

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51 Reads

Studies in Computational Intelligence

This paper studies online child exploitation networks in which users communicate about illegal child pornography material. Law enforcement agencies are extremely interested in better understanding these networks and their key players. We utilize unique real-world network data sets collected from two different online discussion forums on the dark net. Our study of the network structure underlying these forums results in three contributions. First, we propose an approach to identify key players using various centrality measures, allowing us to automatically rank users. Experiments show that our method closely resembles a network-agnostic ranking of users created by domain experts. Second, network metrics are able to characterize a large portion of the users, allowing us to distinguish between regular users, managers and technical moderators. Finally, analyzing the structural properties and distributions of these networks in both the one-mode and two-mode perspective reveals various interesting network-driven insights, such as anti-lurker and anti-law enforcement policies and new user application guidelines. In addition, we found that active users form an elite that participate in more specialized discussions.

Citations (5)


... Een hoger aantal reacties hing zelfs significant negatief samen met de kans op het plaatsen van een volgend bericht. Een mogelijke reden hiervoor zou kunnen zijn dat met name beeldmateriaal dat zeldzaam of nieuw is, van hoge kwaliteit is en/of afbeeldingen bevat van specifieke typen slachtoffers of specifieke seksuele handelingen, het meest gewild is (Owens et al., 2023). Wanneer leden links naar dit type materiaal delen, lokt dit daarom mogelijk ook de meeste reacties uit. ...

Reference:

Communicatiepatronen van leden van een seksueel kindermisbruikforum op het darknet: Een analyse op basis van digitale artefacten
Analysis of topic popularity within a child sexual exploitation Tor hidden service
  • Citing Article
  • November 2022

Aggression and Violent Behavior

... The body of empirical research on the online behaviors of darknet CSAM forum members using digital forensic artifactssystem and user generated traces created during the use of computing technology that can be recovered from computing devices (Rogers et al., 2021) -is, at present, still scant. Van der Bruggen et al. (2022) analyze data on a darknet CSAM forum that had been active between August 2014 to March 2015. They find that only a small percentage (3.4 ...

Even “lurkers” download: The behavior and illegal activities of members on a child sexual exploitation TOR hidden service
  • Citing Article
  • November 2022

Aggression and Violent Behavior

... QDA Miner is a qualitative research tool that organizes, annotates, codes, and analyzes documents and images (Cicea et al., 2021;Fornari & da Fonseca, 2023;Tani̇-Yildiz & Tam, 2023). QDA Miner helps researchers import documents, such as interview transcripts, books, legal documents, photos, and other visual materials (Frimpong et al., 2021;Kloess & Van der Bruggen, 2023). The intuitive interface enables efficient annotation and coding, helping quickly identify themes and patterns (Frimpong et al., 2021). ...

Trust and Relationship Development Among Users in Dark Web Child Sexual Exploitation and Abuse Networks: A Literature Review From a Psychological and Criminological Perspective

Trauma Violence & Abuse

... Online gedrag laat namelijk digitale sporen na -digitale artefacten -die gedetailleerde informatie geven over de activiteiten van personen op dergelijke darknetforums. Eerder onderzoek op basis van zulke digitale artefacten liet bijvoorbeeld zien dat niet alle leden van kindermisbruikforums even actief bijdragen aan het berichtenverkeer op het forum: veel van de online interactie komt op het conto van een kleine groep actieve leden, die hierdoor centrale posities innemen binnen het netwerk (Fonhof et al., 2019;Van der Bruggen & Blokland, 2022). Digitale artefacten stellen wetenschappers in staat om het online delictgedrag van leden van darknetforums direct te observeren, zonder de vertekeningen die optreden wanneer gebruik wordt gemaakt van politiedossiers of vragenlijsten. ...

Profiling Darkweb Child Sexual Exploitation Material Forum Members Using Longitudinal Posting History Data

... For example, script analysis has mainly been used in the study of predatory crimes such as sexual crimes against women and children, robbery and theft [14][15][16][17][18][19] and in cases of check and credit card fraud [20,21], employee cybercrime [22], migrant smuggling [23], antiquities trafficking [24], wildlife trafficking [25], terrorism offenses [26], and money laundering [27,28]. Various authors have used this approach to study organized crime [29][30][31][32][33][34], as recommended in particular by Cornish and Clarke [35]. ...

A Crime Script Analysis of Child Sexual Exploitation Material Fora on the Darkweb
  • Citing Article
  • December 2020

Sexual Abuse A Journal of Research and Treatment