Cloud computing has transformed a large portion of the IT industry through its ability to
provision infrastructure resources – computing, networking, storage, and software - as
services. Software-Defined Networking (SDN) has transformed the physical underlying network
infrastructure into programmable and virtualized networks. Network Functions Virtualization
(NFV) has transformed physical telecommunication infrastructures and network functions into
virtualised network functions and services. Cloud, SDN and NFV technologies and their
associated software-defined infrastructures all rely on the virtualization technology to provision
their virtual resources and offer them as services to users. These new technologies and
infrastructures invariably bring with them traditional vulnerabilities and introduce new
technology-specific security risks. In this paper, we discuss extensively cloud-, SDN-, and NFVspecific
security challenges as well as approaches for addressing integrated infrastructural
issues where cloud, SDN, and NFV all play their integral parts.