Buffer Overflow Lab

Details

Please use C language.

1. define ADMINUID as 0x61646D696E
2. write a structure USER with username in 8 bits buffer and uid
   • variables: username, password(11-bit), uid(5-bit)
3. write a login function using gets to get the user data
   • if there isn’t the username, then create a new user and random the uid.
4. write a menu which design 4 options and 1 of them can show only for admin
   • options:

     1. edit
     2. execute
     3. exit
     7963. flag  (only for admin)

5. write a options function which deal with user’s input.

Source Code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define ADMINUID 0x61646D696E

struct User{
    	char username[100];
    	char password[11];
    	char uid[5];
};

struct User admin = {"admin", "ej03xu3m06", "admin"};
struct User user;
void login();
void menu(char *uid);
void options(int opt);

int main()
{
    	int userOption;
    	
	login();
	scanf("%d", &userOption);
	options(userOption);
	return 0;
}

void login()
{
	printf("Name: ");
	gets(user.username);
	if(strcmp(user.username, admin.username) != 0){
	    	int i;
		for(i = 0;i < 5;i++)
			user.uid[i] = 'a' + (random() % 26); 
	    	printf("User not found. Createing a new user ... \n");
		printf("New Password: ");
		gets(user.password);
		menu(user.uid);	
	}else{
		printf("Password: ");
		gets(user.password);
		if(strcmp(user.password, admin.password) == 0){
		   	 menu(admin.uid);
		}else{
		    	printf("Wrong password.");
			exit(0);
		}
	}
}

void menu(char *uid)
{
	printf("1. edit\n");
	printf("2. execute\n");
	printf("3. exit\n");
	if(strcmp(uid, "admin") == 0){
	    printf("7963. flag\n");
	}
	printf("? ");
}

void options(int opt)
{
	if(opt == 7963){
		printf("FLAG{C0IVGra+ula+i0IV_y0u_jus+_expl0i+_+he_pr0gram_wi+h_buffer_0verfl0vv}");
	}else{
		exit(0);
	}
}