Research paper on covert channels

As part of our MSc study on System and Network Engineering at the University of 
Amsterdam, NL, Marc Smeets and I have done research on covert channels. 

Abstract:

"Covert channels have been topic of discussion within both academic and 
non-academic communities for more than two decades. Traditionally, research on 
this topic focussed on storage and timing channels within singular systems. As 
more systems became interconnected in the last decade, the scope expanded to 
network-based covert channels. Numerous designs and implementations of such 
covert channels have been suggested, altogether leaving the world with valuable 
pieces of knowledge scattered around the Internet. By aggregating the 
essentials and representing them in a structured format, we attempt to provide 
clarity on the current state of research. In addition, a (non-exhaustive) 
overview of contemporary trends in network-based covert channels is given, 
explaining common channels within IP, TCP, ICMP, HTTP and DNS. Lastly, several 
implementations were evaluated to gain insight in their efficiency and 
performance, and the influences to which they're prone. We conclude that they p
 ose a security issue that needs proper attention when defining and enforcing 
security policies, and expect more sophisticated covert channels to appear in 
the future."

The paper is available at the following URL:

http://www.os3.nl/~mrkoot/courses/RP1/researchreport_2006-02-15_final2.pdf

Feedback is more than welcome!

(I posted to bugtraq since the secpapers list appears rather dormant)