Advances in Shellcode
From this article in Phrack, breaksdown the difference between shellcode and exploits, and offers example of different approaches to creating the backdoor.
www.phrack.org: "http://www.eeye.com/html/Research/Advisories/AL20010717.html"
www.phrack.org: "http://www.eeye.com/html/Research/Advisories/AL20010717.html"