Abstract-The article deals with the issues of the security of distributed and scalable computer systems based on the risk-based approach. The main existing methods for predicting the consequences of the dangerous actions of the intrusion agents are described. There is shown a generalized structural scheme of job manager in the context of a risk-based approach. Suggested analytical assessments for the security risk level in the distributed computer systems allow performing the critical t ime values forecast for the situation analysis and decisionmaking for the current configuration o f a distributed computer system. These assessments are based on the number of used nodes and data links channels, the number of act ive security and monitoring mechanisms at the current period, as well as on the intensity of the security threats realization and on the activation intensity of the intrusion prevention mechanis ms. The proposed comprehensive analytical risks assessments allow analyzing the dynamics of intrusions processes, the dynamics of the security level recovery and the corresponding dynamics of the risks level in the distributed computer system. Index Terms-Distributed computer systems, Security analysis, Risk-based approach. NOMENCLATURE α -the average intensity of the security threats for the distributed computer systems resources x1 and x2; β -the average intensity of the security mechanis ms from the group x3 and x4 activation; R 0 -the initial security risk; R(t) -security risks in the distributed computer systems, changing at time t;x 1 -the number of nodes in the distributed computer system;x 2 -the number of data link channels;x 3 -the number of the active security mechanisms; x 4 -the number of the security monitoring tools in the distributed computer systems;x 1max -the maximu m nodes number in a distributed computer system; x 2max -the maximu m number of data link channels; x 3max -the maximu m nu mber of the active security mechanisms;x 4max -the maximu m nu mber o f the security monitoring tools in the distributed computer systems.