There has been a lot of effort in the research on routing in mobile ad hoc networks in the last years. Promising applications of MANETs, e.g. in the automotive domain, are the drive for the design of inter-vehicle networks. So far, several projects in this field have chosen geographic routing approaches because of their outstanding performance and the possibility to support location-based applications like traffic warning functions. Having reached a reasonable functional level, a next step will be a deeper study of safety and security issues.
With this paper, we dive into that area by assuming defective or malicious nodes that disseminate wrong position data. First, we have a look at the local problems that may arise from falsified position data, then we show the global effects on the routing performance by simulating malicious nodes. Simulation results show that the overall ratio of successfully delivered messages decreases, depending on the number of maliciously acting nodes, even up to approximately 30%. We conclude from this result that future work should take these threats into account in order to design more robust routing protocols.