Frida For Reversing and Dynamic Instrumentation

With a little free time on my hands I thought I would give frida.re another go and dig into it’s capabilities.

A friend a work volunteered  to write a simple binary challenge for me to use frida to solve it.

I will do a proper writeup later, but for now you can find the code here.

Notes of interest:

I was able to hook the xor function but not in time to prevent the main process from firing it off the xor function and causing my tests to be inaccurate. My workaround was to read the section of memory (xor key) that the xor function changed before it was changed, then restore the memory back after the initial xor call. From this point on, I was able to call the xor function freely and reset the memory back again for subsequent calls to bruteforce.

 

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