  Open Radio Access Network (O-RAN), a novel architecture that separates the
traditional radio access network (RAN) into multiple disaggregated components,
leads a revolution in the telecommunication ecosystems. Compared to the
traditional RAN, the proposed O-RAN paradigm is more flexible and more
cost-effective for the operators, vendors, and the public. The key design
considerations of O-RAN include virtualization and intelligent capabilities in
order to meet the new requirements of 5G. However, because of the open nature
and the newly imported techniques in O-RAN architecture, the assessment of the
security in O-RAN architecture during its early development stage is crucial.
This project aims to present an investigation of the current ORAN architecture
from several attack surfaces, including (1) Architectural openness, (2) Cloud
and Virtualization, (3) Network slicing, and (4) Machine Learning. The existing
attack surfaces and corresponding mitigation methods of these attacks are also
surveyed and provided in this report, serving as a guiding principle and
valuable recommendation for the O-RAN implementers and framework designers.
