Buffer Overflow

static data

use by the user progam is stored int he global data segnment

dynamic data

by the user program is stored in the heap

stack

used by the user program to store temporary data during subroutine calls

kernel segment

stores kernel level code and static data

frame

chunk of data for a given function

stack oprations

push and pop

ebp

start of the current frame

esp

end of the current frame

eip

next instruction

hacker process

study the target system

find a place to put attack code

overflow - change the flow of execution

guessing

() where the shellcode is can be time consuming and can lead to a segmentation fault ir invalid instruction even if you are wrong by 1 byte

padding

() shellcode with NOP’s and then guessing doesnt require knowing the exact byte and is much more efficient

environment variable

you can squeeze shellcode into smaller buffers by storing the shellcode in an () then overflow the buffer with the address of this variable in memory

Smashing the stack

() works by injecting code into a program using a buffer overflow, and getting the program to jump to that code