Clouds are tricky things. It’s hard to tell where the foundations of a cloud reside. You could point at the physical infrastructure. Some of the best side-channel attacks target hardware. There is the operating system that runs everything. And there is the middleware, billing, hypervisors, drivers and web front ends. The potential attack surface of a cloud service provider (CSP) or consumption market platform is gigantic.
Article Link: https://blog.fortinet.com/2017/08/07/tornado-warning-commingling-of-public-and-iot-clouds