Foreword

For better or worse, there are moments in our lives that we can visualize with startling clarity. Sometimes momentous and other times trivial, we’re able to completely recall these snippets of our past even if we can’t remember the day or context. In my life, there’s one moment I’d like to call trivial, but the truth is, it was likely more central in establishing my eventual technology career than I care to admit at social gatherings.

I think it was the early 1980s, but that’s mostly irrelevant. My best friend’s parents recently purchased an Apple II (plus, I think), making my friend the first person I knew with a computer in his house. One day we noticed a seam on the top of the plastic case; we slid the bulking green screen monitor to the side and removed the panel on the top. For the first time, we peered into the inner guts of an actual working computer. This was definitely before the release of WarGames, likely before I’d ever heard of hacking, and long before “hacker” became synonymous with “criminal” in the mass media. We lifted that plastic lid and stared at the copper and black components on the field of green circuit boards before us. We were afraid to touch anything, but for the first time, the walls between hardware and software shattered for our young minds, opening up a new world of possibilities. This was something we could touch, manipulate, and, yes, break.

My young computer career began with those early Apples (and Commodores). We spent countless hours exploring their inner workings; from BASIC to binary math, and more than our fair share of games (for the record, the Apple joystick was terrible). Early on I realized I enjoyed breaking things just as much, if not more than, creating them. By feeling around the seams of software and systems, learning where they bent, cracked, and failed, I could understand them in ways just not possible by coloring between the lines.

The very first Mac I could buy was an early Mac Mini I purchased mostly for research purposes. I quickly realized that Mac OS X was a hacker’s delight of an operating system. Beautiful and clean compared to my many years on Windows, with a Unix terminal a click away. Here was a box I could run Microsoft Office on that came with Apache by default and still held full man pages. As I delved into Applescript, plists, DMGs, and the other minutia of OS X, I was amazed by the capabilities of the operating system, and the breadth and depth of tools available.

But as I continued to switch completely over to Apple, especially after the release of Intel Macs, my fingers started creeping around for those cracks at the edges again. I wasn’t really worried about viruses, but, as a security professional, I started wondering if this was by luck or design. I read the Apple documentation and realized fairly early that there wasn’t a lot of good information on how OS X worked from a security standpoint, other than some configuration guides and marketing material.

Mac security attitudes have changed a fair bit since I purchased that first Mac Mini. As Macs increase in popularity, they face more scrutiny. Windows switchers come with questions and habits, more security researchers use Macs in their day-to-day work, the press is always looking to knock Apple down a notch, and the bad guys won’t fail to pounce on any profitable opportunity. But despite this growing attention, there are few resources for those who want to educate themselves and better understand the inner workings of the operating system on which they rely.

That’s why I was so excited when Dino first mentioned he and Charlie were working on this book. Ripping into the inner guts of Mac OS X and finding those edges to tear apart are the only ways to advance the security of the platform. Regular programming books and system overviews just don’t look at any operating system from the right perspective; we need to know how something breaks in order to make it stronger. And, as any child (or hacker) will tell you, breaking something is the most exhilarating way to learn.

If you are a security professional, this book is one of the best ways to understand the strengths and weaknesses of Mac OS X. If you are a programmer, this book will not only help you write more secure code, but it will also help you in your general coding practices. If you are just a Mac enthusiast, you’ll learn how hackers look at our operating system of choice and gain a better understanding of its inner workings. Hopefully Apple developers will use this to help harden the operating system; making the book obsolete with every version. Yes, maybe a few bad guys will use it to write a few exploits, but the benefits of having this knowledge far outweigh the risks.

For us hackers, even those of us of limited skills, this book provides us with a roadmap for exploring those edges, finding those cracks, and discovering new possibilities. For me, it’s the literary equivalent of sliding that beige plastic cover off my childhood friend’s first Apple and gazing at the inner workings.

—Rich Mogull

Security Editor at TidBITS and Analyst at Securosis