Can I get source code back again in .exe program?

[omer123]

Hi.
If I make an .exe program, can I decompile it again to get source code?
Is there a possible way to do that? If No, then, even the one who created that programming language, weather, it's in C++, Jave or whatever it's, can't get the source code again from an exe program?

[helios]

Even if we ignore obvious things like variable names, comments, and whitespace style, getting the exact source code for C and C++ programs is completely impossible. Twenty years ago it was somewhat possible, but modern compilers use such aggressive optimizations that an optimized program bears little resemblance to the source from which it was generated. There exist decompilers for C++, but they're only usable to get a general idea of what a single function is doing. Really, they're only a step above looking at the disassembly.

Java programs are an entirely different matter. Decompiling bytecode is comparatively trivial. If the program was built with debugging symbols, you may even be able to see get back variable and function names.

[omer123]

So, how a hacker can hack a program, if he/she can't get the source code of that exe program?
I know there are DICTIONARY and BRUTE FORCE attacks, but I mean except of these ways.
Even the one who created that programming language, can't get the source code of a program that someone else has created?

By the way, I don't mean how to hack a program and what we need. I just want to know a general overview of assembly.
Thanks.

[helios]

So, how a hacker can hack a program, if he/she can't get the source code of that exe program?

A successful reverse engineer must be able to read disassembly, understand what it's supposed to do, and write new code that behaves equivalently. This is different from decompilation because no attempt is made to reconstruct the original code. Being able to obtain functionally equivalent code is sufficient.

I know there are DICTIONARY and BRUTE FORCE attacks, but I mean except of these ways.

Dictionary and brute force attacks are methods to crack password systems. It has nothing to do with RCE.

Even the one who created that programming language, can't get the source code of a program that someone else has created?

Of course not. Just like the person who invented and encryption algorithm can't recover your data if you lose the key. Some operations are just irreversible.

[omer123]

Interesting. Thanks helios so much.