Penetration Testing and Network Defense

Chapter 14. Understanding and Attempting Buffer Overflows

Of all men’s miseries the bitterest is this: to know so much and to have control over nothing.

—Herodotus

Imagine a van with four passengers and a driver. The driver gets to control the direction of the van. She gets to drop off and pick up passengers along the way. This is the way a buffer operates in a computer. A buffer contains both code and data variables that a user inputs. A buffer has pointers, like the van driver, that direct what to do when you get to the end of the buffer.

Now imagine that five passengers get into the van. The van has room for only four passengers and a driver. If five new passengers get in to replace the existing passengers, then all four seats for the passengers ...