The number and increasing complexity of attacks against MANETs have grown significantly in recent years. While many security proposals have been developed. However, these proposals suffer from the problems of tests and evaluations. Among these solutions, the Intrusion Detection Systems (IDS) that can act as defense mechanisms. However, this last poses serious problems for its evaluators that need classify the attacks to select case test. In this paper, we make a thorough analysis of existing attack classifications in order to determine whether they could be helpful in selecting attack test cases. Based on our analysis, we construct a new scheme to classify attacks relying on those attributes that appear to be the best classification criteria. We also apply the Classification Tree Method (CTM) to select test-case to attack. Finally, we use the Classification Tree Editor (CTE) tool to generate and select test-case.