The Shellcoder's Handbook: Discovering and Exploiting Security Holes, Second Edition

Introduction to the Second Edition

Wherever terms have a shifting meaning, independent sets of considerations are liable to become complicated together, and reasonings and results are frequently falsified.

— Ada Augusta, Countess of Lovelace, from her notes on "Sketch of The Analytical Engine," 1842

You have in your hands The Shellcoder's Handbook Second Edition: Discovering and Exploiting Security Holes. The first edition of this volume attempted to show the reader how security vulnerabilities are discovered and exploited, and this edition holds fast to that same objective. If you're a skilled network auditor, software developer, or sysadmin and you want to understand how bugs are found and how exploits work at the lowest level, you've come to the right place.

So what's this book about? Well, the preceding quotation more or less sums it up. This book is mostly concerned with arbitrary code execution vulnerabilities, by which we mean bugs, that allow attackers to run code of their choice on the target machine. This generally happens when a program interprets a piece of data as a part of the program — part of an http "Host" header becomes a return address, part of an email address becomes a function pointer, and so on. The program ends up executing the data the attacker supplied with disastrous effects. The architecture of modern processors, operating systems, and compilers lends itself toward this kind of problem — as the good Countess wrote, "the symbols of operation are frequently ...