Platooning employs a set of technologies to manage how a group of vehicles operates, including radar, GPS and Inter-Vehicular Communication (IVC). It uses broadcasted information such as acceleration, position and velocity to operate vehicle members of the platoon. Cooperation among vehicles allows platoons to reduce fuel consumption and risks associated with driver mistakes. In spite of these benefits, the use of IVC to control vehicles exposes a relevant attack surface that can be exploited by malicious actors. In this paper we study the impact of vulnerabilities associated with the Sybil attack (through falsification of multiple identities) and message falsification in vehicular platooning. Simulation results show that this attack may impact the longitudinal control and compromise the entire platoon control.