The goal of the system hacking is to be able to authenticate to the remote or targeted host with the highest level of access. There are several ways this can be attempted including buffer overflow, exploiting a vulnerability, sniffing a password, guessing a password, social engineering, etc.

Denial of Service

A variation of the SYN attack is a reflective attack. An attacker launches a reflective attack by sending a large number of SYN packets to a web server but alters the source address so it is spoofed to match the address of the victim. The web server responds to the large number of SYN packets by issuing a flood of traffic back to the spoofed victims address. The victim sees the flood of traffic as an attack.

Buffer Overflow

Buffer overflows are usually categorized according to the memory region in which the overflow occurs. The stack area of memory serves a variety of purposes, such as passing arguments to functions, storing local variables, and keeping track of where execution should return to when the current function is finished executing.

Example of a Stack Overflow

void func(char *str)

{

        char name[64];

        strcpy(name,str);

        printf("Hello, %s\n",name);

}

 int main(int argc, char **argv)

{

        if(argc < 2)  {

       printf("Usage: %s name\n",argv[0]);

       return –1;

        }

        func(argv[1]);

        return 0;

}