The Rootkit Arsenal: Escape and Evasion in the Dark Corners of the System, 2nd Edition

Chapter 14  Covert Channels

 

In the most general sense, a covert channel is just a way of exchanging information in a manner that makes the act of exchange difficult to perceive. This could entail repackaging the data that’s exchanged. For example, during World War II, spies often transmitted photographs as microdots, which were then embedded as periods in otherwise mundane postal correspondence.

Another way to implement a covert channel is to use an unconventional conduit. For instance, in South Asian countries, it’s possible to move money around outside of official money-transfer lines by use of an informal network of brokers known as a “hawala.” Not only are the requirements to move cash less stringent, but also a hawala operates completely ...