Covert Channels are the mechanism used to transmit information using not the originally intended for Data Transmission.

​Generally Unauthorized and hidden used to send information that violates Information security policy.

*Covert Storage Channels* - They are a line of communication that can be seen by everyone but not understand by everyone.  Processes are able to communicate through some type of storage on the system. 
* Stagnograhy is a type of Covert Storage Channel. Example - Hiding a picture or a message inside a PDF Document. 

*Covert Timing Channel*  - One precess relays information to another by modulating  the use of system resources. For example, mixing illegitimate traffic with legitimated traffic.

Micro-Architectural Attacks
* Cache Timing Attacks 
* Cache memory sits in between processor and memory. It is used for faster processing.