Introduction
If money could be said to exist anywhere in a network, it exists on a database server. When we say that modern economies are reliant on computers, what we really mean is that modern economies are reliant on database systems. Databases are behind the systems that affect almost every aspect of our lives — our bank accounts, medical records, pensions, employment records, phone records, tax records, car registration details, supermarket purchases, our children's school grades — almost every piece of information of significance in our lives is stored in a modern relational database management system. Since this volume covers seven of the most popular relational database systems, chances are that your personal information is currently being stored in the very systems that are the subject of this book.
We (the authors of this volume) consider database security to be the single most important information security issue there is. If database systems — the systems we all implicitly trust to hold our most sensitive data — are not secure, the potential impact on our lives, and even on our broader society, could be devastating.
Why then do we want to publish a book that describes methods for attacking databases? Simply put, we want to put this information into the hands of database administrators, security professionals, and network auditors so that the people whose job it is to defend these systems understand more fully how others attack them. The people we are all defending against already fully understand how to attack databases and networks; their continued liberty depends on that fact. This volume is likely to teach them little they didn't already know. Contrary to what most software vendors would have you believe, finding security bugs isn't very hard. For every bug that an independent researcher reports to a vendor, there are likely to be several bugs that are known to people who don't inform the vendor. We believe that the best way to defend your network — and your databases — against these unknown bugs is to understand in detail the mechanics of the bugs we know about and attempt to create configurations that thwart whole classes of bugs, rather than simply patching and hoping that no one attacks you with a 0-day exploit.
More often than not, securing a database is a matter of applying the tried-and-tested principles that have been used in network security for decades — enforce minimal privilege, reduce "attack surface" by removing unnecessary functionality, be strict about authentication and access controls, separate blocks of functionality into distinct areas, enforce encryption . . . the only real difference is that in a database, all of these mechanisms operate within the miniature world of the database itself.
It's tempting to read vendor literature pertaining to security and be reassured by the plethora of security measures that modern databases implement. Almost all database systems have some notion of privilege, access controls, comprehensive audit facilities, and controlled access to system components. Database vendors vie with each other to obtain security certifications that prove that they have appropriately implemented these mechanisms. The problem is that although these certifications are important, they are only a part of the story, and by no means the most important part.
All of the databases discussed in this volume have been subject to buffer overflows that violate almost all of these security mechanisms. Placing our faith in security standards, evaluations, and accreditations isn't working. It's time to get practical, and that's what this book is all about.
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