Essential PHP Security

Being highly flexible in building dynamic, database-driven web applications makes the PHP programming language one of the most popular web development tools in use today. It also works beautifully with other open source tools, such as the MySQL database and the Apache web server. However, as more web sites are developed in PHP, they become targets for malicious attackers, and developers need to prepare for the attacks. Security is an issue that demands attention, given the growing frequency of attacks on web sites. "Essential PHP Security" explains the most common types of attacks and how to write code that isn't susceptible to them. By examining specific attacks and the techniques used to protect against them, you will have a deeper understanding and appreciation of the safeguards you are about to learn in this book. In the much-needed (and highly-requested) "Essential PHP Security," each chapter covers an aspect of a web application (such as form processing, database programming, session management, and authentication). Chapters describe potential attacks with examples and then explain techniques to help you prevent those attacks. Topics covered include: Preventing cross-site scripting (XSS) vulnerabilities Protecting against SQL injection attacks Complicating session hijacking attempts You are in good hands with author Chris Shiflett, an internationally-recognized expert in the field of PHP security. Shiflett is also the founder and President of Brain Bulb, a PHP consultancy that offers a variety of services to clients around the world. Essential PHP Security......Page 1 Table of Contents......Page 3 Copyright......Page 9 Foreword......Page 11 Preface......Page 13 What's Inside......Page 15 Style Conventions......Page 17 Comments and Questions......Page 19 Safari Enabled......Page 21 Acknowledgments......Page 23 Chapter 1. Introduction......Page 25 Section 1.1. PHP Features......Page 27 Section 1.2. Principles......Page 31 Section 1.3. Practices......Page 35 Chapter 2. Forms and URLs......Page 45 Section 2.1. Forms and Data......Page 47 Section 2.2. Semantic URL Attacks......Page 51 Section 2.3. File Upload Attacks......Page 55 Section 2.4. Cross-Site Scripting......Page 59 Section 2.5. Cross-Site Request Forgeries......Page 61 Section 2.6. Spoofed Form Submissions......Page 67 Section 2.7. Spoofed HTTP Requests......Page 69 Chapter 3. Databases and SQL......Page 73 Section 3.1. Exposed Access Credentials......Page 75 Section 3.2. SQL Injection......Page 77 Section 3.3. Exposed Data......Page 83 Chapter 4. Sessions and Cookies......Page 85 Section 4.1. Cookie Theft......Page 87 Section 4.2. Exposed Session Data......Page 89 Section 4.3. Session Fixation......Page 91 Section 4.4. Session Hijacking......Page 97 Chapter 5. Includes......Page 101 Section 5.1. Exposed Source Code......Page 103 Section 5.2. Backdoor URLs......Page 105 Section 5.3. Filename Manipulation......Page 107 Section 5.4. Code Injection......Page 111 Chapter 6. Files and Commands......Page 113 Section 6.1. Traversing the Filesystem......Page 115 Section 6.2. Remote File Risks......Page 119 Section 6.3. Command Injection......Page 123 Chapter 7. Authentication and Authorization......Page 125 Section 7.1. Brute Force Attacks......Page 127 Section 7.2. Password Sniffing......Page 131 Section 7.3. Replay Attacks......Page 133 Section 7.4. Persistent Logins......Page 135 Chapter 8. Shared Hosting......Page 141 Section 8.1. Exposed Source Code......Page 143 Section 8.2. Exposed Session Data......Page 147 Section 8.3. Session Injection......Page 153 Section 8.4. Filesystem Browsing......Page 157 Section 8.5. Safe Mode......Page 161 Appendix A. Configuration Directives......Page 163 Section A.1. allow_url_fopen......Page 165 Section A.2. disable_functions......Page 167 Section A.3. display_errors......Page 169 Section A.4. enable_dl......Page 171 Section A.5. error_reporting......Page 173 Section A.6. file_uploads......Page 175 Section A.7. log_errors......Page 177 Section A.8. magic_quotes_gpc......Page 179 Section A.9. memory_limit......Page 181 Section A.10. open_basedir......Page 183 Section A.11. register_globals......Page 185 Section A.12. safe_mode......Page 187 Appendix B. Functions......Page 189 Section B.1. eval( )......Page 191 Section B.2. exec( )......Page 193 Section B.3. file( )......Page 195 Section B.4. file_get_contents( )......Page 197 Section B.5. fopen( )......Page 199 Section B.6. include......Page 201 Section B.7. passthru( )......Page 203 Section B.8. phpinfo( )......Page 205 Section B.9. popen( )......Page 207 Section B.10. preg_replace( )......Page 209 Section B.11. proc_open( )......Page 211 Section B.12. readfile( )......Page 213 Section B.13. require......Page 215 Section B.14. shell_exec( )......Page 217 Section B.15. system( )......Page 219 Appendix C. Cryptography......Page 221 Section C.1. Storing Passwords......Page 223 Section C.2. Using mcrypt......Page 225 Section C.3. Storing Credit Card Numbers......Page 229 Section C.4. Encrypting Session Data......Page 231 About the Author......Page 233 Colophon......Page 235 Index......Page 237 SYMBOL......Page 239 A......Page 241 B......Page 243 C......Page 245 D......Page 247 E......Page 249 F......Page 251 G......Page 253 H......Page 255 I......Page 257 L......Page 259 M......Page 261 N......Page 263 O......Page 265 P......Page 267 Q......Page 269 R......Page 271 S......Page 273 T......Page 275 U......Page 277 V......Page 279 temp0110.html......Page 281 Highly flexible in building dynamic, database-driven web applications, the PHP programming language is one of the most popular web-development tools in use today. It also works beautifully with other open source tools, such as the MySQL database and the Apache web server. However, as more web sites are developed in PHP, they inevitably become targets for malicious attackers. Developers need to prepare for this; security is an issue that demands attention.The much-needed (and highly requested) Essential PHP Security explains the most common types of attacks and how to write code that can withstand such attacks. By examining specific attacks and the techniques used to protect against them, you will have a deeper understanding and appreciation of the safeguards you are about to learn in this book.Each chapter of this book covers an aspect of a web application (such as form processing, database programming, session management, and authentication). The chapters provide examples of potential attacks and then explain techniques to help you prevent those attacks. You are in good hands with author Chris Shiflett, an internationally recognized expert in the field of PHP security. Shiflett is also the founder and president of Brain Bulb, a PHP consultancy that offers a variety of services to clients around the world. This book is for web developers looking to expand their knowledge of creating secure php code, it explains the techniques sometimes used by hackers to gain entry into your website and also explains how to prevent or reduce the chances of those issue occurring to you.