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Fast and Furious Reverse Engineering

Teddy Rogers

About This File

One of the greatest challenges of modern reverse engineering is taking apart and analyzing software protections. During the last decade a vast number of such shell modifiers have appeared. Software Protection as an industry has come a long way from simple encryption that protects executable and data parts to current highly sophisticated protections that are packed with tricks aiming at slow down in the reversing process. Number of such techniques increases every year. Hence we need to ask ourselves, can we keep up with the tools that we have?

Protections have evolved over the last few years, but so have the reversers tools. Some of those tools are still in use today since they were written to solve a specific problem, or at least a part of it. Yet when it comes to writing unpackers this process hasn't evolved much. We are limited to writing our own code for every scenario in the field.

We have designed TitanEngine in such fashion that writing unpackers would mimic analyst's manual unpacking process. Basic set of libraries, which will later become the framework, had the functionality of the four most common tools used in the unpacking process: debugger, dumper, importer and realigner. With the guided execution and a set of callbacks these separate modules complement themselves in a manner compatible with the way any reverse engineer would use his tools of choice to unpack the file. This creates an execution timeline which parries the protection execution and gathers information from it while guided to the point from where the protection passes control to the original software code. When that point is reached file gets dumped to disk and fixed so it resembles the original to as great of a degree as possible. In this fashion problems of making static unpackers have been solved. Yet static unpacking is still important due to the fact that it will always be the most secure, and in some cases, fastest available method. That is why we will discuss both static and dynamic unpackers.. We will also see into methods of making generic code to support large number of formats without knowing the format specifics.

TitanEngine can be described as Swiss army knife for reversers. With its 250 functions, every reverser tool created to this date has been covered through its fabric. Best yet, TitanEngine can be automated. It is suitable for more than just file unpacking. TitanEngine can be used to make new tools that work with PE files. Support for both x86 and x64 systems make this framework the only framework supporting work with PE32+ files. As such, it can be used to create all known types of unpackers. Engine is open source making it open to modifications that will only ease its integration into existing solutions and would enable creation of new ones suiting different project needs.

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