Table of Contents for
System Forensics, Investigation, and Response, 3rd Edition

Version ebook / Retour

Cover image for bash Cookbook, 2nd Edition System Forensics, Investigation, and Response, 3rd Edition by Easttom Published by Jones & Bartlett Learning, 2017
  1. Cover Page
  2. Contents
  3. System Forensics, Investigation, and Response
  4. Title Page
  5. Copyright Page
  6. Content
  7. Preface
  8. About the Author
  9. PART I Introduction to Forensics
  10. CHAPTER 1 Introduction to Forensics
  11. What Is Computer Forensics?
  12. Understanding the Field of Digital Forensics
  13. Knowledge Needed for Computer Forensics Analysis
  14. The Daubert Standard
  15. U.S. Laws Affecting Digital Forensics
  16. Federal Guidelines
  17. CHAPTER SUMMARY
  18. KEY CONCEPTS AND TERMS
  19. CHAPTER 1 ASSESSMENT
  20. CHAPTER 2 Overview of Computer Crime
  21. How Computer Crime Affects Forensics
  22. Identity Theft
  23. Hacking
  24. Cyberstalking and Harassment
  25. Fraud
  26. Non-Access Computer Crimes
  27. Cyberterrorism
  28. CHAPTER SUMMARY
  29. KEY CONCEPTS AND TERMS
  30. CHAPTER 2 ASSESSMENT
  31. CHAPTER 3 Forensic Methods and Labs
  32. Forensic Methodologies
  33. Formal Forensic Approaches
  34. Documentation of Methodologies and Findings
  35. Evidence-Handling Tasks
  36. How to Set Up a Forensic Lab
  37. Common Forensic Software Programs
  38. Forensic Certifications
  39. CHAPTER SUMMARY
  40. KEY CONCEPTS AND TERMS
  41. CHAPTER 3 ASSESSMENT
  42. PART II Technical Overview: SystemForensics Tools, Techniques, and Methods
  43. CHAPTER 4 Collecting, Seizing, and Protecting Evidence
  44. Proper Procedure
  45. Handling Evidence
  46. Storage Formats
  47. Forensic Imaging
  48. RAID Acquisitions
  49. CHAPTER SUMMARY
  50. KEY CONCEPTS AND TERMS
  51. CHAPTER 4 ASSESSMENT
  52. CHAPTER LAB
  53. CHAPTER 5 Understanding Techniques for Hiding and Scrambling Information
  54. Steganography
  55. Encryption
  56. CHAPTER SUMMARY
  57. KEY CONCEPTS AND TERMS
  58. CHAPTER 5 ASSESSMENT
  59. CHAPTER 6 Recovering Data
  60. Undeleting Data
  61. Recovering Information from Damaged Media
  62. File Carving
  63. CHAPTER SUMMARY
  64. KEY CONCEPTS AND TERMS
  65. CHAPTER 6 ASSESSMENT
  66. CHAPTER 7 Email Forensics
  67. How Email Works
  68. Email Protocols
  69. Email Headers
  70. Tracing Email
  71. Email Server Forensics
  72. Email and the Law
  73. CHAPTER SUMMARY
  74. KEY CONCEPTS AND TERMS
  75. CHAPTER 7 ASSESSMENT
  76. CHAPTER 8 Windows Forensics
  77. Windows Details
  78. Volatile Data
  79. Windows Swap File
  80. Windows Logs
  81. Windows Directories
  82. Index.dat
  83. Windows Files and Permissions
  84. The Registry
  85. Volume Shadow Copy
  86. Memory Forensics
  87. CHAPTER SUMMARY
  88. KEY CONCEPTS AND TERMS
  89. CHAPTER 8 ASSESSMENT
  90. CHAPTER 9 Linux Forensics
  91. Linux and Forensics
  92. Linux Basics
  93. Linux File Systems
  94. Linux Logs
  95. Linux Directories
  96. Shell Commands for Forensics
  97. Kali Linux Forensics
  98. Forensics Tools for Linux
  99. CHAPTER SUMMARY
  100. KEY CONCEPTS AND TERMS
  101. CHAPTER 9 ASSESSMENT
  102. CHAPTER 10 Macintosh Forensics
  103. Mac Basics
  104. Macintosh Logs
  105. Directories
  106. Macintosh Forensic Techniques
  107. How to Examine a Mac
  108. Can You Undelete in Mac?
  109. CHAPTER SUMMARY
  110. KEY CONCEPTS AND TERMS
  111. CHAPTER 10 ASSESSMENT
  112. CHAPTER 11 Mobile Forensics
  113. Cellular Device Concepts
  114. What Evidence You Can Get from a Cell Phone
  115. Seizing Evidence from a Mobile Device
  116. JTAG
  117. CHAPTER SUMMARY
  118. KEY CONCEPTS AND TERMS
  119. CHAPTER 11 ASSESSMENT
  120. CHAPTER 12 Performing Network Analysis
  121. Network Packet Analysis
  122. Network Traffic Analysis
  123. Router Forensics
  124. Firewall Forensics
  125. CHAPTER SUMMARY
  126. KEY CONCEPTS AND TERMS
  127. CHAPTER 12 ASSESSMENT
  128. PART III Incident Response and Resources
  129. CHAPTER 13 Incident and Intrusion Response
  130. Disaster Recovery
  131. Preserving Evidence
  132. Adding Forensics to Incident Response
  133. CHAPTER SUMMARY
  134. KEY CONCEPTS AND TERMS
  135. CHAPTER 13 ASSESSMENT
  136. CHAPTER 14 Trends and Future Directions
  137. Technical Trends
  138. Legal and Procedural Trends
  139. CHAPTER SUMMARY
  140. KEY CONCEPTS AND TERMS
  141. CHAPTER 14 ASSESSMENT
  142. CHAPTER 15 System Forensics Resources
  143. Tools to Use
  144. Resources
  145. Laws
  146. CHAPTER SUMMARY
  147. KEY CONCEPTS AND TERMS
  148. CHAPTER 15 ASSESSMENT
  149. APPENDIX A Answer Key
  150. APPENDIX B Standard Acronyms
  151. Glossary of Key Terms
  152. References
  153. Index

Firewall Forensics

Examining the firewall should be a fundamental part of any network forensic analysis. Because all external traffic must come through the firewall, it is imperative that the firewall logs be examined carefully. They frequently contain valuable evidence.

Firewall Basics

A basic working understanding of firewalls is required to do proper firewall forensics. There are several ways to categorize firewalls, but there are two that are more basic than the rest: packet filtering and stateful packet inspection.

Packet Filter

This is the most basic type of firewall. It simply filters incoming packets and either allows them entrance or denies them passage based on a set of rules. This is also referred to as a screened firewall. It can filter packets based on packet size, protocol used, source IP address, and so on. Many routers offer this type of firewall option in addition to their normal routing functions.

Stateful Packet Inspection

The stateful packet inspection (SPI) firewall examines each and every packet, denying or permitting not only based on the current packet, but also considering previous packets in the conversation. This means that the firewall is aware of the context in which a specific packet was sent. This makes these firewalls far less susceptible to ping floods, SYN floods, and spoofing.

Application Filter

This type of firewall combines stateful packet inspection with scanning for specific application issues. For example a Web Application Firewall (WAF) will scan for typical web attacks such as SQL injection and cross-site scripting.

Collecting Data

All the traffic going through a firewall is part of a connection. A connection consists of two IP addresses that are communicating with each other and two port numbers that identify the protocol or service. The concatenation of an IP address and a port number is called a socket, and it is unique while it is active. The three ranges for port numbers are as follows:

  • Well-known ports—The well-known ports are those from 0 to 1023.

  • Registered ports—The registered ports are those from 1024 to 49151.

  • Dynamic ports—The dynamic, or private, ports are those from 49152 to 65535.

Attempts on the same set of ports from many different Internet sources are usually due to decoy scans. In a decoy scan strategy, an attacker spoofs scans that originate from a large number of decoy machines and adds his or her IP address somewhere in the mix.

Earlier in this chapter, you learned a list of common ports. You should carefully check the firewall logs for any sort of connections or attempted connections on those ports. You also learned about packet flags that might indicate a port scan. If your firewall logs such details, you need to scan the log for any packets that might indicate a scan.

Using protocol analysis may help you determine who the attacker is. For example, you can ping each of the systems and match up the Time to Live (TTL) fields in those responses with the connection attempts. The TTL is not actually a time, per se, but rather the number of routers between a source and destination. The TTLs should match, plus or minus one or two in case the route is slightly different. If the TTL of the captured traffic and the TTL of the test/trace traffic don’t match closely, the addresses are being spoofed by an attacker. One drawback is that to know the actual number of hops, you must know the starting TTL that is being used. The idea of the TTL is that an IP packet is discarded when its TTL, decreased at each intermediate router, reaches zero before the packet gets to its destination.

Analyze the firewall logs in depth to look for decoy addresses originating from the same subnets. You will likely see that the attacker has connected recently, whereas the decoyed addresses have not.