Hello!I'm new here, so, in my course i have to crack a program written by my teacher, he said that its a simple crack, this program have a message like:"This is a free program", i need to find the JNZ Short Command in runtime, but de address of this code is indefined, it changes everytime i open the program, so i need to search and change the JNZ to JMP...
Anyone knows some way to do that?

If you are using Window (or DOS) and the code is for 80x86, you can use DEBUG to see the code running (and step through it one command at a time).

After you see HOW it is written, you can better determine how to modify it by adding on to the beginning and end of the program (and save it as a larger file).