The stack is a memory space in which any data can be stored. The stack can be accessed using the stack pointer register (for 32-bit address space, the ESP register is used). Let's consider the example of the following code snippet:
push 0 push 21646c72h push 6f57206fh push 6c6c6548h mov eax, esp push 74h push 6B636150h mov edx, esp push 0 push eax push edx push 0 mov eax, <user32.MessageBoxA> call eax
This will eventually display the following message box:
How did that happen when no visible text strings were referenced? Before calling for the MessageBoxA function, the stack would look like this:
These push instructions assembled the null terminated message text at the stack.
push 0 push 21646c72h push 6f57206fh push 6c6c6548h
While the other string was assembled with these push instructions:
push 74h push 6B636150h
In effect, the stack dump would look like this.
Every after string assembly, the value of register ESP is stored in EAX and then EDX. That is, EAX points...