In recent years, threats in wireless ad hoc networks (WANETs) could be further divided into outside and insider threats. It is important to consider that the majority of insider threats come from the users who are fully authorized to use the systems they are accessing. This new situation would greatly inhibit the normal activity for data communications, and cause the WANETs to spend a longer time for delivering the same data volumes. Therefore, a Trust-Based Cooperation Authentication Bit-Map Routing Protocol (TCABRP) against insider threats in WANETs is proposed in this paper. It could reduce the damages away from the insider threats in a WANET. Specifically, the cooperation evaluations are employed that include three factors: cooperative scores, cooperative trust values and authenticated codes. The routing protocol is not only a type of behavioral-based technique but also a kind of efficient cryptographic protocol. The cooperative evaluations route vector could protect the chain of the router vector authentication codes for verifying the delivery process and determining whether it is correct or incorrect. Moreover, the proposed routing protocol in WANET could not only prevent InTs efficiently, but also evaluate the behaviors of the compromised node or a selfish node as well.