Buffer Overflow and Steganography

Ethical Hacking Lab 5

Buffer Overflow and Steganography

Determine the conditions for a buffer overflow to occur and use Steganography to demonstrate the manner to hide messages within a picture or other media.

Given the program below:

#include <stdio.h>

#include <string.h>

void foo(int a, int b, int c)

{

int tmp;

a=2;

tmp = b+c*a;

}

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

{

int pass = 0;

char buff[15];

 

foo(3,4,5);

printf(“\n Enter the password : \n”);

gets(buff);

if(strcmp(buff, “testpilot”))

{

printf (“\n Wrong Password \n”);

}

else

{

printf (“\n Correct Password \n”);

pass = 1;

}

if(pass)

{

/* Now Give root or admin rights to user*/

printf (“\n Root privileges given to the user \n”);

}

return 0;

}

Assume the program is in a file called: test.c

It is compiled and linked using gcc test.c –a test

and is executed as ./test

Show the activation records up to where the arrow indicates:

Parameter right-to-left local variables top-to-bottom word size is 32 bits

Show what input, other than testpilot will give root privileges.

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What are DEP and ASLR?

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How do these techniques prevent attacks on the system?

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Given the following original and stego images

Determine

The maximum percentage of changed bits _____________________

The actual number of changed bits ___________________________

Using the original image, but now using single bit (lsb) and only hiding the letter c,

The maximum percentage of changed bits _____________________

The actual number of changed bits ___________________________