Experts publish 'how to' book for software exploits

A new book by leading security researchers on writing code to exploit security flaws in software, including Microsoft Corp.'s Windows operating system, has caused some raised eyebrows in the technical community for publishing "zero day," or previously unknown, techniques for exploiting vulnerable systems.

"The Shellcoder's Handbook: Discovering and Exploiting Security Holes," is an advanced guide to writing software exploits. The book is intended as a resource for network administrators who are interested in closing security holes. However, the book also contains working examples of code for exploiting vulnerable systems and previously unpublished techniques for launching attacks such as heap overflows and kernel attacks, according to two of the book's authors.

Shellcode is a term that describes small pieces of computer code that launch operating system "shells," or command interfaces such as the common "C:\" command line interface on Microsoft DOS (Disk Operating System). Shellcode is often a component of attacks in which malicious hackers use software exploits to get control of vulnerable systems.

The new book is published by John Wiley & Sons Inc. and is scheduled to be released on March 22, 2004. It contains chapters on a variety of attack types, including stack overflows, heap overflows and format string bugs. Authors discuss everything from how to write Windows shellcode to exploiting security holes in Hewlett-Packard Co.'s (HP's) Tru64 operating system, according to a description of the book published on the Wiley Web page.

Also contained in the new guide are fully-functional examples of software exploits, according to co-author Dave Aitel, founder of Immunity Inc. of New York City, a security consulting company.

"The book is trying to teach you how to write exploits, so of course there are exploits," he said.

Aitel contributed chapters on heap overflows and Windows exploits to the book, as well a technique for finding flaws in network communications protocols called "fuzzing," he said.

The information contained in the new book is essential to administrators who want to secure the computer systems under their management, he said.

"It's hard to get context on a (software) vulnerability if you don't know how to exploit it. People who know how to write exploits make better strategic decisions," he said.

Co-author Chris Anley agreed and said the Shellcoder's Handbook is not a cookbook for hackers.

"This isn't a collection of exploits. It's a book that tells you how to find the bugs and understand what the impact of the bugs is," said Anley, a director at Next Generation Security Software Ltd. (NGSSoftware) in Surrey, U.K.

"We wanted to make a book that describes from basic through advanced level what exploits can do," he said.

The book is structured like a primer. Early chapters focus on basic concepts like stack overflows and use examples written for the open source Linux platform. Later chapters focus on more complicated problems and obscure operating systems such as Sun Microsystems Inc.'s Solaris and HP's Tru64, Anley said.