Collaborating against ransomware: insights from the Melissa project

Abstract

In response to the increase in scale, complexity, and impact of ransomware attacks, Public-Private Partnerships (PPPs) are widely regarded as a key strategy for addressing this threat. However, not much is known about how such collaborations function in practice, what factors contribute to their success, and which challenges may undermine their sustainability. This article presents an in-depth evaluation of Melissa, a Dutch initiative that brings together public and private actors to combat ransomware through structured information sharing and coordinated action. This study draws on document analysis, semi-structured interviews, a focus group and literature review to examine Melissa’s program theory, effectiveness, and the factors that facilitate or hinder successful collaboration and long-term impact. The findings suggest that Melissa has strengthened trust and reciprocity among stakeholders, enabled systematic information exchange, and contributed to concrete operational successes—including international disruption of ransomware groups—while enhancing societal resilience through accessible knowledge products. Success factors include expertise, intrinsic motivation, social cohesion, and effective leadership, whereas vulnerabilities stem from voluntary participation, legal and ethical constraints, and reliance on a small number of key individuals. As such, this article contributes to a broader understanding of how to design and sustain effective public-private partnerships in cybersecurity governance.