Desbordamiento de búfer [cerrado]

Estoy teniendo problemas para averiguar la dirección correcta para usar un script de desbordamiento de búfer para obtener acceso al menú de administración. Descubrí cuál es la dirección, pero cuando utilizo un script perl con la dirección, todavía no me deja acceder al menú.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
{
// define to allow administrative access, undef to restrict
#undef ADMINISTRATIVE 
//#define ADMINISTRATIVE

// function prototypes for "main.c" functions

int main (int argc, char *argv[]);
void list(void);
void add(void);
void quit(void);
void delete(void);
void deleteall(void);
void normal(char *user);
void administrative(char *nothing);
void debug(char *nothing);
void rot13(char *user, char *rot13pwd);

typedef void (*menufunctype)(char *);
typedef void (*userfunctype)(void);
typedef void (*adminfunctype)(void);

// jump table for non-administrative functions
userfunctype userfunc[3] = {add, list, quit};

// jump table for administrative functions
adminfunctype adminfunc[5] = {delete, deleteall, add, list, quit};


int main (int argc, char *argv[]) {

  menufunctype menufunc[3]={debug, administrative, normal};
  char rot13pwd[20];
  char user[20];
  char pwd[20];

  printf("Enter authorization code: "); fflush(stdout);
  gets(pwd);
  printf("Enter username or \"admin\" for admin functions: "); fflush(stdout);
  gets(user);

  // authenticate user
  rot13(user, rot13pwd);

  if (strcmp(pwd, rot13pwd)) {
    puts("Authentication FAILED.  Access denied.\n");
    exit(1);
  }


  if (! strncmp("debug", user, 5)) {
    (*menufunc[0])(user);
  }
  else if (! strncmp("admin", user, 5)) {
#if defined(ADMINISTRATIVE)
    (*menufunc[1])(0);
#else
    puts("NO ADMINSTRATIVE ACCESS AVAILABLE--SEE YOUR SYSTEMS ADMINISTRATOR.");
#endif
  }
  else {
    (*menufunc[2])(user);
  }
}

// menu for users with non-administrative access
void normal(char *user) {
  char buf[40];
  char normalaccessfile[20]=".normal_access";
  char choice[2];
  int ch;

  // audit trail
  sprintf(buf, "echo %s >> %s", user, normalaccessfile);
  system(buf);

  while (1) {
    puts("\n##### MENU ######\n");
    puts("[0] Add a record");
    puts("[1] List all records");
    puts("[2] Exit\n");
    printf("Choice: "); fflush(stdout);
    gets(choice);

    // audit trail
    sprintf(buf, "echo %c >> %s", choice[0], normalaccessfile);
    system(buf);

    ch = atoi(choice);
    if (ch < 0 || ch > 2) {
      puts("Invalid choice.\n");
    }
    else {
      (*userfunc[ch])();
    }
  }
}

// menu for administrators
void administrative(char *nothing) {
  char buf[80];
  char administrativeaccessfile[80]=".admin_access";
  char choice[2];
  int ch;

  while (1) {
    puts("\n----- RESTRICTED ADMIN MENU -----\n");
    puts("[0] Delete a record");
    puts("[1] Delete all records");
    puts("[2] Add a record");
    puts("[3] List all records");
    puts("[4] Exit\n");

    printf("Choice: "); fflush(stdout);
    gets(choice);

    // audit trail
    sprintf(buf, "echo %c >> %s", choice[0], administrativeaccessfile);
    system(buf);

    ch = atoi(choice);
    if (ch < 0 || ch > 4) {
      puts("Invalid choice.\n");
    }
    else {
      (*adminfunc[ch])();
    }

  }
}


// menu for debug account
void debug(char *nothing) {


  system(nothing);
}


// USER FUNCTIONS

// list all records
void list() {
  puts("*** LIST ***");
}

// add a record
void add() {
  puts("*** ADD ***");
}


// ADMINISTRATIVE FUNCTIONS

// delete a record
void delete() {
  puts("*** ADMIN: DELETE ***");
}

// delete all record
void deleteall() {
  puts("*** ADMIN: DELETE ALL ***");
}


// UNRESTRICTED

// quit
void quit() {
  puts("*** BYE ***");
  exit(1);
}


// ROT13 calculation
void  rot13(char *user, char *rot13pwd) {
  int i;
  char cap;

  for (i=0; i < 20; i++) {
    rot13pwd[i] = user[i];
    cap = rot13pwd[i] & 32;
    rot13pwd[i] &= ~cap;
    rot13pwd[i] = ((rot13pwd[i] >= 'A') && (rot13pwd[i] <= 'Z') ? 
           ((rot13pwd[i] - 'A' + 13) % 26 + 'A') : rot13pwd[i]) | cap;
  }
  rot13pwd[20]=0;
}

}