Some weird dynamic memory stuff, but looks like secure...

cursedheap.c

#include <stdio.h>
#include <stdlib.h>


int main() {
    int* state = (int*) calloc(sizeof(int),1024);
    int* admin_flag = &state[1023];
    *admin_flag = 0;
    free(state);
    char* str = malloc(4096);
    char* line = malloc(128);
    scanf("%127s", line);
    snprintf(str, 4096, line);
    if (*admin_flag==12852) {
        printf("You won!\n");
    }
    free(str);
    return 0;
}