AFL usually requires you to write a "driver" for the program you want to fuzz. The driver does two main things: 1. Take a binary blob of input and pass it to t

AFL usually requires you to write a "driver" for the program you want to fuzz. The driver does two main things: 1. Take a binary blob of input and pass it to the program somehow. 2. Record execution path traces into a shared memory section. You could likely modify the Ruby VM to record path traces, and handle the binary blob in Ruby code.