Challenges

Challenge 3 Binary Patching

Scenario: You have a program which you need to find the license key to use it, luckily the key is somewhere in the binary.

Binary patching

Find the license key compile on your own machine :


Source:

Code:

#include <string.h>
#include <stdio.h>
int main(int argc, char *argv[]) {
if(argc==2) {
printf("Checking License: %s\n", argv[1]);
if(strcmp(argv[1], "AAAA-Z10N-42-OK")==0) {
printf("Access Granted!\n");
} else {
printf("WRONG!\n");
}
} else {
printf("Usage: <key>\n");
}
return 0;
}

Tools:
nano (text editor)
gcc
Ghidra/Cutter or any debugger

OS-Linux(Ubuntu)

Compile: gcc -o license license.c
(compiles fine to warnings)