This crackme is from crackmes.de (actually down). It has been created by thetrh51. The used language is C/C++ and it should run on Unix/Linux.

If we take a look at main function with objdump, we see a compraison instruction, which makes a jump to <main+0x43> if it’s equals or to <main+0x5c> if it’s not.

To figure it out:

main+0x43: movl $0x80488cb,0x4(%esp) where 0x80488cb is the string “YOURE IN!!”

main+0x5c: jmp 80487d2 <main+0x66> where <main+0x66> is the leave instruction.

So, we should satisfy the following comparison:

Where the immediate value is 0x4d2, or 1234 in decimal. Let’s try:

And done ✅