One of the attacks that has high impact on the mobile cognitive radio network is the primary user emulation that can disable the entire system for the transmission or reception of information, it's divided in malicious and selfish attack according to the attack main objective. Energy detection is a mechanism for primary user detection or primary user emulation attack on this networks. This work focuses on the detection of energy for the malicious primary user emulation attack. The test environment is developed over software-defined radio in NI-USRP 2922 devices. Experiments estimate the probabilities of detection and false alarm of an attacker and are compared with theoretical models, showing its operation over detection of this specific attack.