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Structure

FoRREST is structured as a set of Python classes. The primary class, FoRREST, contains basic features for manipulating the object (load a file, call the shell, etc.). The remaining classes are referred to as Plugins, and are divided according to the levels of information representation described below.

Levels of Information Representation

The information found in a binary can be represented in many ways and on many different levels. You start on a low-level with very simplistic information and as you extract data, you start to get higher-level information.

Level 0: Raw Data

  • Filename - The name of the file that you are working with.
  • Extension - The name of the extension for the file you are working with if it's present.
  • Size - The size of the file you are working with.
  • inode - The physical location the file on the file system.
  • Path - The path that leads to the file.
  • Checksums - The digest value obtained by running a hashing algorithm on the raw data.

Level 1: Extracted Data

  • Filetype - The type of file which is denoted by a sequence of bits at the start of a file. This is considered the mime type.
  • Version - The version numbers of the program (if used).
  • Architecture - The architecture that the program was compiled for.
  • Compiler - The compiler that was used to generate the file (if known).
  • Sections - The name and offset addresses that divide the file into meaningful paritions.

Level 2: Interpreted Data

  • Opcodes - The bytes from the .text section that can be decoded into a stream of opcodes. The .text is the binary's actual code.
  • Strings - A list of strings from the .data section and other sections.
  • Imports - A list of functions the program references from a linked object file.
  • Exports - A list of variables and function addresses made available to outside programs.
  • Header Information - Information about how the program is organized.

Level 3: Transformed Data

  • Disassembly - The output from the transformation from a binary file to an assembly file.
  • Mnemonics - The portion of the assembly instruction that is related to the action being preformed.
  • Functions - The list of addresses that are discovered from analyzing the targets of call instructions.
  • Basic Blocks - The directed graph of basic blocks that can be constructed by analyzing the boundaries and control flow of instructions.
  • Data References - The location of data values derived from interpreting memory store and load operations.
  • Jump Targets - The memory address offsets obtained by analyzing the targets of conditional and unconditional control flow change instructions.

Level 4: Inferred Data

  • Control Flow Graph - Control flow graphs (CFGs) are visual representations of basic blocks that include arrows signifying which blocks a given block calls or is called by
  • System Calls - System call traces determine what operating system functions the program attempts to access.
  • Function Traces - Function traces note sequences of functions that are executed, and in what order.
  • Program Slices - Program slices are sub-sequences of code that affect the value of a variable through assignment or some other operation.
  • Intermediate Representation - Intermediate representation (IR) is a form of expanded assembly code, that breaks each processor instruction into multiple steps to explicitly define every action necessary to perform the instruction.
  • Decompilation - Decompiled source code is the final step in the transition from the original string of bytes to a high-level, human-readable programming language. It is, ideally, very similar to the original source code that created the executable.
  • Stack Frames - Stack frames are records of the program stacks built in memory when calling functions within the program, i.e. parameter values, local variables, and return addresses.
  • Packet Captures - Packet captures are sets of data that are collected whenever a program tries to communicate over a network
  • Symbolic Execution - Symbolic execution of programs allows for analysis of potential paths without using concrete input. This is done by automated analysis tools which substitute symbols for the values of variables.
  • Deobfuscation - Obfuscation makes exeuctables very hard to reverse engineer. Developers may obfuscate their code for many reasons, from wanting to protect their intellectual property to disguising a program's true intent because it's malicious. Obfuscation can also happen unintentionally when a compiler optimizes code. Deobfuscation attempts to simplify the code in order to make it clear what the developer's intent was