Classic code from 1999+ I am fairly sure this is the first public polymorphic shellcode ever (best IMHO and others http://ids.cs.columbia.edu/sites/default/files/ccs07poly.pdf :) If I ever port this to 64 or implement a few other suggestions (sorry I lost ppc code version contributed) it will be orders of magnitude more difficult to spot, so I hope nobody uses signatures for anything (virus / malware scanners included).