InlineWhispers

A Proof of Concept for weaponizing SysWhispers for making direct system calls in Cobalt Strike Beacon Object File.

The initial output (functions.txt and syscalls-asm.h) are created as an example for WdToggle.

Additional guidance can be found in this blog post: https://outflank.nl/blog/?p=1592

Raphael Mudge (the creator of Cobalt Strike) created a tutorial video on how to use this tool: https://www.youtube.com/watch?v=mZyMs2PP38w

What is this repository for?

Demonstrate the ability to easily use syscalls using inline assembly in BOFs.

How do I set this up?

• (Optionally) Install SysWhispers
  • git clone https://github.com/jthuraisamy/SysWhispers.git
  • cd SysWhispers
  • pip3 install -r .\requirements.txt
  • py .\syswhispers.py --versions 7,8,10 -o syscalls was used to generate the included syscalls.asm and syscalls.h.
• Clone this repository.
• Update which functions are required in functions.txt to include only necessary functions from syscalls.asm.
• Run the python InlineWhispers.py command to generate the inline assembly (syscalls-asm.h) header file.
• Remove function definitions in Syscalls.h that are not included.
• Include Syscalls.h in your project.

Limitations

• The Syscalls.h header file provided includes many extern function definitions by default. This can lead to compilation without actually having the function included in your object (if not removed).
• Inline assembly is only supported by Mingw-w64. Visual Studio does not support inline assembly.

Credits

• The assembly code used within this tool is based on the assembly output from the SysWhispers tool from @Jackson_T.
• All people credited for SysWhispers