A system is used for detection of advanced persistent and non-persistent threats in a computerized environment. The system is connected to a plurality of user devices coupled to an enterprise's network. The system receives via an interface an electronic notification of at least one event in the operating system of the computer. The system then analyzes the at least one event. The system then generates a causality chain for the at least one event respective of the analysis. The causality chain comprises all the threads that attributed to the at least one event in a chronological order. The system then identifies a main thread that started the causality chain that led to the at least one event. Then, the system determines whether the main thread is associated with malicious software. Upon determination that the main thread is associated with malicious software, the causality chain is marked as infected.