The attack surface at this layer are many – mostly through micro-architectural and platform vulnerabilities. Examples of such problems surfaced most recently with leading processors with Meltdown and Spectre vulnerabilities. These were exposed because of aggressive micro-architectural optimizations such as use of out-of-order execution of instructions in processors. Platform architecture includes the memory architecture, the interconnection network in multiprocessor chip, and various protocol interfaces. These also use aggressive micro-architectural optimizations and in the recent past researchers have been finding various security flaws most of which either breach confidentiality of data in memory, or in cache hierarchy, or can even create disruption or data integrity challenges.
The major problems to consider at this layer are:
i. Micro-architectural optimizations which lead to cyber vulnerabilities
ii. Platform architecture designs and optimizations exposing security vulnerabilities.