ADVobfuscator demonstates how to use C 11/14 language to generate, at compile time, obfuscated code without using any external tool and without modifying the compiler. The technics presented rely only on C 11/14, as standardized by ISO. It shows also how to introduce some form of randomness to generate polymorphic code and it gives some concrete examples like the encryption of strings literals and the obfuscation of calls using finite state machines.

ADVobfuscator is delivered as a set of source file (source code library). You have to include them into your project and call the appropriate functions or macro. This is not a magic black box or some kind of code pre-processor or post-processor. It has to be integrated manually into your source code.

If you are looking for a more transparent obfuscator, look at Obfuscator-LLVM or strong.codes (commercial version of Obfuscator-LLVM). Note: I have no affiliation with Obfuscator-LLVM and strong.codes. I just know some of those swiss folks.

• Enhance the compatibility with compiler's optimizer (such as GCC with O3). Previously, the code was sometimes overoptimized by the compiler and as a consequence, non-obfuscated strings remains in the binary code. This was more or less due to a bug in ADVobfuscator (I was not using volatile).
• Fix a stupid mistake in algorithm #2 (shift). Sometimes, the encryption key is 0.
• Clearly seperate the library code (under Lib) from the examples (under Examples and DocCode).
• Check the compatibility with C 14. In the future, I will probably drop the support of C 11 and keep only C 14 and C 17 compatibility.

Several enhancement (suppress warnings, fix some errors, enhance portability). In more details:

• Increase the warning level for Visual Studio and GCC
• Remove several (all) compilation warnings
• Replace int by size_t when it is appropriate (sizeof, position)
• Remove unused parameters
• Keys are now of type char (were of type int, it was wrong)
• Replace the non-portable ##__VA_ARGS__ by the portable __VA_ARGS__. As a consequence, new macros (ending with 0) are defined when there are no parameters
• Remove some (stupid) syntax errors (; at the end of some functions). C/C is odd: you have to put a ; when you define a struct, but none when you define a function
• A integral type is computed at compile time to store pointers to functions

ADVobfuscator code has been updated for Visual Studio 2015. ADVobfuscator is now compatible with the RTM release of Visual Studio 2015 (previous versions or CTP releases are not). The whitepaper is not yet updated. The code has also been modified in order to avoid problems with O3 optimization and GCC. GCC with O3 defeats obfuscation (because it optimizes too much) and sometimes generates wrong code (not clear yet if it is a bug in GCC or in ADVobfuscator).

First you have to follow the requirements below. Then, you just have to include ADVobfuscator header files and use macros such as OBFUSCATED to protect your strings or function calls.

Look at the examples in the Examples folder.

• A C 11 or C 14 compatible compiler (i.e. a compiler that is not too old)
• Obfuscated strings: no other prerequisite
• Obfuscated calls and predicates: You have to install the Boost library. See below

You have to install the Boost library in order to use some features of ADVdetector (it is used by FSM). To install Boost:

• Debian / Ubuntu: sudo apt-get install libboost-all-dev
• Mac OS X: brew install boost
• Windows: Download Boost and install it. Then you have to change the Visual Studio project to point to Boost

cd Examples
make

Each example is in its subdirectory.

Open ADVobfuscator.xcworkspace and build each example.

Open ADVobfuscator.sln. Be sure to change the path to Boost library for each project (Properties | C/C | General | Additional Include Directories).

Debug builds are very special: Compiler do not have (and do not most of the time) respect statement such as inline or constexpr. All optimizations are also, by default, disabled. Compilers are doing this for a good reason: let you debug, single step, etc.

As a consequence, ADVobfuscator is not compatible with Debug builds. It works only for Release builds.

ADVobfuscator has been tested with:

• Xcode (LLVM) 8.1.0 under Mac OS X 10.12
• GCC 7.2.0 under Debian 10 (buster - testing)
• Visual Studio 2017 (15.3.3) under Windows 10
• Boost 1.65.0

Other compilers are probably compatible if they are C 11/14 compliant.

These are ideas for the next few months:

• Create version 5 of MetaString: instead of choosing one algorithm, it will combine several. This way, tools such as XOR breakers will not work.
• Switch to C 14 and C 17. It will simplify some parts of the code and C is now well supported by compilers such as GCC and CLANG
• Try to better support Visual Studio 2015, but only if it does not implies a restructuring of the code
• Introduce White Box Cryptography (AES in particular). Still in my mind but I am not very active for the moment
• Is my code compatible with ASLR? In fact, I don't konw and I have to solve this (I need it for another project)
• Apply the techniques used in MetaString4.h into ObfuscatedCall.h
• )ntroduce Unit Testing

Written by Sebastien Andrivet - Copyright © 2010-2017 Sebastien Andrivet.

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