Reversing Skype Binary – Silver Needle in the Skype [pdf] (2006)
secdev.org
secdev.org
The most remarkable thing is their idea of what they call "Twin processes debugging", which is: debug one process, but use the other one to count checksums which are checked randomly in runtime.
https://archive.org/details/Fabrice_Desclaux_and_Kostya_Kort...
Slides and other files from that presentation can be found here: http://2006.recon.cx/en/f/