Sonic.exe is a fan-made horror game based on the Sonic the Hedgehog franchise, and it doesn't have any official soundtrack. Any music associated with the game is typically sourced from other Sonic games, remixes, or fan-made compositions.
If you are referring to a specific song you have heard, please provide more details such as the name of the song or its source. This will help me understand what you are asking and provide an accurate answer.