  Edge-enabled Vehicular Ad Hoc Network (VANET) introduces real-time services
and storage, computation, and communication facilities to the vehicles through
Roadside Units (RSUs). Nevertheless, RSUs are often easy targets for security
assaults due to their placement in an open, unprotected environment and
resource-constrained nature. The malicious RSUs compromised by security attacks
impose threats to human safety by impeding the operations of VANETs. Hence, an
effective malevolent RSU detection mechanism is crucial for VANETs. Existing
trust-based detection mechanisms assign trust scores to RSUs based on their
interactions with moving vehicles where precise detection of rogue RSUs depends
on the accuracy of trust scores. However, brief interaction of RSUs with the
running vehicles permits inadequate time to estimate trust accurately. Besides,
current works use only vehicle speed and density in beacon messages to assess
trust without considering the sensor-detected data in the same messages.
Nonetheless, sensor data is useful for traffic management, and neglecting them
creates inaccuracy in trust estimation. In this paper, we address these
limitations and propose a trust-based scheme to detect malicious RSUs that uses
stable and frequent RSU-to-RSU (R2R) interaction to precisely analyze the
behavior of an RSU. We also offer a mechanism to detect alteration of
sensor-detected data in beacon content and incorporate this scheme in the trust
calculation of RSUs. The experimental results show that the proposed solution
effectively detects approximately 92% malicious RSUs, even in the presence of
hostile vehicles. Moreover, integrating the proposed solution with the VANET
routing protocols improves routing efficiency.
