In the multimedia applications over the mobile ad hoc networks, the goodput and delay performance of UDP packets is very sensitive to the congestion targeted DDoS attacking. In this paper, we analyze this type of attacking in details for the first time to our knowledge. We figure out the principles of the attacking from the analysis of network capacity and classify the attacking into four categories: Pulsing attacking, Round Robin attacking, Self-whisper attacking and Flooding attacking. The defense schemes are also proposed, which includes the detection of RTS/CTS packets, signal interference frequency and retransmission time and response stage with ECN marking mechanism. Through the ns2 simulation, the basic attacking scenario is discussed and the results show that the attacking leads to the great jitter of the goodput and delay in pulsing attacking mode. The delay increasing (up to 110 times in five attacking flows) and goodput decreasing (to 77.42% in 5 attacking flows) is obvious with the addition of attacking flows.