In this paper we implement and evaluate the most prominent attacks described in literature in a consistent manner to provide a concise comparison on attack types and parameters. Our objective is to thoroughly capture and analyze the impact of a range of attacks on MANET performance. To this end we define performance metrics and explore influence and damage caused by several attack types and parameter sets. Our evaluation results show that the degree of impact of attacks differs significantly depending on attack type and parameters used. The impact of a particular attack increases considerably with an increasing number of attacking nodes in several of the scenarios, whereas other attack impact levels remain almost constant with varying number of attackers. These results imply that an attacker could choose an attack strategy from a number of alternatives with similar overall impact thereby minimizing detection risk. Our performance metrics provide a consistent comparison of various attack types and parameters and thus a deeper insight into the interaction and the impact of attacks in MANETs.