  Distributed ledger technologies have gained significant attention and
adoption in recent years. Despite various security features distributed ledger
technology provides, they are vulnerable to different and new malicious
attacks, such as selfish mining and Sybil attacks. While such vulnerabilities
have been investigated, detecting and discovering appropriate countermeasures
still need to be reported. Cybersecurity knowledge is limited and fragmented in
this domain, while distributed ledger technology usage grows daily. Thus,
research focusing on overcoming potential attacks on distributed ledgers is
required. This study aims to raise awareness of the cybersecurity of
distributed ledger technology by designing a security risk assessment method
for distributed ledger technology applications. We have developed a database
with possible security threats and known attacks on distributed ledger
technologies to accompany the method, including sets of countermeasures. We
employed a semi-systematic literature review combined with method engineering
to develop a method that organizations can use to assess their cybersecurity
risk for distributed ledger applications. The method has subsequently been
evaluated in three case studies, which show that the method helps to
effectively conduct security risk assessments for distributed ledger
applications in these organizations.
