Due to the increasing digitalization in all areas of society, such as IoT, cloud computing or industry 4.0, IT attacks are becoming more frequent, especially through cyber espionage using Advanced Persistent Threats (APT). When new security solutions are developed, they must be tested and evaluated for applicability, performance, efficiency and coverage. Since such complex solutions can’t be used in real environments without testing, they have to be tested and evaluated in simulations. We therefore focus our research on the simulation of IT environments in which almost realistic conditions exist. This includes the realistic simulation of IT users as well as attackers and defenders.