Exploiting stack-based buffer overflows

Now that our basics are clear, let's move on to the exploitation of stack-based buffer overflows.

How to do it...

The following steps demonstrate the stack-based buffer overflow:

1. Let's take a look at another simple C program:

        #include<stdio.h> 
        #include<string.h> 
        void main(int argc, char *argv[]) 
        { 
            char buf[120]; 
            strcpy(buf, argv[1]); 
            printf(buf); 
        }  

This program uses a vulnerable method strcyp(). We save the program to a file.

2. We then compile the program with gcc using the fno-stack-protector and execstack:

        gcc -ggdb name.c -o name -fno-stack-protector -z execstack

3. Next, we turn off address space randomization using this:

        echo 0 > /proc/sys/kernel/randomize_va_space

4. Now we open our program in gdb using this command:

        gdb ./name

The following screenshot shows the output of the preceding command:

5. Next, we supply our input using Python using the...