Despite of their energy efficiency, most of WSN’s cluster-based routing protocols are vulnerable to security threats. Selective forwarding and black hole attacks are ranked among the most devastating attacks which they target this class of routing protocols. In this paper, a new centralized intrusion detection system is proposed to detect selective forwarding and black hole attacks in cluster-based wireless sensors networks. The main idea is the use of a centralized detection approach, where the base station decides on potential intrusions based on control packets sent from the cluster heads. The proposed intrusion detection technique is simple and energy efficient, it is thus suitable for sensor nodes with resource constrained. The simulation results confirm the expected performance of the proposed IDS in terms of security and energy efficiency.