A free, open-source software reverse engineering suite that can be used to attempt binary decompilation on a processor level.
The Ecosystem Response
Tools like or Ghidra (with custom MQL4 loaders) can show the assembly-level logic. This requires deep expertise but produces accurate, malware-free output.
If you have an old EA (check the file date; pre-2014 is safe), here’s how to use the classic decompiler: