Shadow Digital Economy (SDE) is a sector of economic relations covering all types of production and economic activities that, in their focus, content, nature and form, contradict the requirements of the law and are being carried out contrary to state regulation of the economy and bypassing control over it. The paper provides an interaction model between the main segments of the shadow digital economy and an analysis of statistical information characterizing these segments. The paper provides an analysis of the category "Shadow Digital Technologies" (SDT), their components such as information systems, users’ activity or inactivity, basic processes and rules, as well as the formation of new challenges and threats to the security of the individual, society and the state. Particular attention is paid to the transition elements: from shadow digital technologies to a shadow digital economy - the economic component has always been the final goal of criminal activity. The authors note that SDT and SDE are socio-economic phenomena, they are a set of developed, but underground markets for information and software products and services, have an ultra-high intellectual potential, a large amount of material and financial resources, and huge economic opportunities. By their structure, these markets are heterogeneous both, in terms of volumes and prospects for causing damage to the individual, society and the state. The paper concludes that the application of new digital technologies in the economy brings new challenges and risks. It can be stated that digital services control level decreases while opportunities for the implementation of a wide range of illegal actions for information leakage increases. Completely new threats appear, and these threats are related to the explosive growth of the importance of social networks in the life of society and the introduction of new technologies, such as artificial intelligence, virtual/augmented reality, the Internet of Things (IoT) and the influence on the operation of equipment (for example, household appliances, cardiostimulators, etc.). At the end of the article, we formulated the main risks related to implementation and adoption of cryptocurrencies by financial institutions. The review of the threats confronting concepts would allow states to stimulate the introduction and development of new financial technologies in a controlled manner by once side, as well as mitigating potential risks, by the other side.