  The Open Radio Access Network (O-RAN) is a promising RAN architecture, aimed
at reshaping the RAN industry toward an open, adaptive, and intelligent RAN. In
this paper, we conducted a comprehensive security analysis of Open Radio Access
Networks (O-RAN). Specifically, we review the architectural blueprint designed
by the O-RAN alliance -- A leading force in the cellular ecosystem. Within the
security analysis, we provide a detailed overview of the O-RAN architecture;
present an ontology for evaluating the security of a system, which is currently
at an early development stage; detect the primary risk areas to O-RAN;
enumerate the various threat actors to O-RAN; and model potential threats to
O-RAN. The significance of this work is providing an updated attack surface to
cellular network operators. Based on the attack surface, cellular network
operators can carefully deploy the appropriate countermeasure for increasing
the security of O-RAN.
