The energy allocation problem of malicious denial-of-service (DoS) attacks for state estimation in cyber-physical systems (CPSs) is investigated in this chapter. An optimal energy allocation strategy for DoS attacks in CPSs under multi-sensor network fusion estimation is proposed. To describe the channel packet loss characteristic, a signal-to-interference-plus-noise ratio (SINR) model is introduced. Compared with the existing DoS attack strategies, the increase of the channel packet loss rate with the increase in energy injected by the attacker is considered. Meanwhile, the behavioral tendency of the attacker concerning the sensors with different parameters is taken into account, leveraging the additional sensing accuracy matrix. Moreover, the quantified relationship between the attacker and the remote estimator error covariance is derived and the optimal energy allocation strategy problem is transformed into a convex optimization problem to be solved. Finally, a simulation example is presented to verify the effectiveness of the proposed mechanism.