  In this study, we attempt to add to the literature of Connected and Automated
Vehicle (CAV) security by incorporating the security vulnerabilities and
countermeasures of the Vehicular Ad hoc Networks (VANETs) and their access
technologies. Compounding VANETs and modern vehicles will allow adversaries to
gain access to the in-vehicle networks and take control of vehicles remotely to
use them as a target or a foothold. Extensive attention has been given to the
security breaches in VANETs and in-vehicle networks in literature but there is
a gap in literature to assess the security vulnerabilities associated with
VANETs access technologies. That is, in this paper we contribute to the CAV
security literature in threefold. First, we synthesize the current literature
in order to investigate security attacks and countermeasures on VANETs as an ad
hoc network. Second, we survey security challenges that emerge from application
of different VANETs access technologies. To augment this discussion, we
investigate security solutions to thwart adversaries to compromise the access
technologies. Third, we provide a detailed comparison of different access
technologies performance, security challenges and propound heterogeneous
technologies to achieve the highest security and best performance in VANETs.
These access technologies extend from DSRC, Satellite Radio, and Bluetooth to
VLC and 5G. The outcome of this study is of critical importance, because of two
main reasons: (1) independent studies on security of VANETs on different strata
need to come together and to be covered from a whole end-to-end system
perspective, (2) adversaries taking control of the VANETs entities will
compromise the safety, privacy, and security of the road users and will be
followed by legal exposures, as well as data, time and monetary losses.
