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Infeasibility of Modeling Polymorphic Shellcode

This is a very interesting paper from some smart people at Columbia University. Here is my layman's summary for the terminally lazy:

Intro (paraphrase):
We are going to model the feasibility of modeling polymorphic shellcode to see if we can rely on antivirus heuristics and behavioral detection techniques.

Body (paraphrase):
Examine a ton of models & do some math that makes my head hurt.

"Our empirical results demonstrate the difficulty of modeling polymorphic behavior. We briefly summarized the achievements of the shellcoder community in making their code polymorphic and examined ways to improve some of these techniques. We presented analytical methods that can help assess the capabilities of polymorphic engines and applied them to some state-of-the-art engines. We explained why signature–based modeling works in some cases and confirmed that the viability of such approaches matches the intuitive belief that polymorphism will eventually defeat these methodologies. The strategy of modeling malicious behavior leads to an unending arms race with an attacker. Alternatively, whitelisting normal content or behavior patterns (perhaps in randomized ways in order to defend against blending attacks) might ultimately be safer than blacklisting arbitrary and highly varied malicious behavior or content."

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While sitting in SANS SEC511 I listened to @sethmisenar lament the difficulty in using existing tools to detect DGA (Dynamically Generation Algorithm) hostnames used by malware. There are lots of AI based tools out there that do this but some are rather complex. I thought I could quickly write a tool that would work. In about 30 minutes I threw together some old code I had lying around from a SQL Inction tool I worked on and I had a working proof of concept. was born and it worked pretty well. A year later @securitymapper had me wrap it in a web interface so he could query it from a SIM and then the tool took off. It turns out to be a pretty effective technique and gained some popularity and wide use! This is a rewrite of the tool that incorporates some lessons learned and performance enhancments.
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