Book Image

Learn Computer Forensics

By : William Oettinger
Book Image

Learn Computer Forensics

By: William Oettinger

Overview of this book

A computer forensics investigator must possess a variety of skills, including the ability to answer legal questions, gather and document evidence, and prepare for an investigation. This book will help you get up and running with using digital forensic tools and techniques to investigate cybercrimes successfully. Starting with an overview of forensics and all the open source and commercial tools needed to get the job done, you'll learn core forensic practices for searching databases and analyzing data over networks, personal devices, and web applications. You'll then learn how to acquire valuable information from different places, such as filesystems, e-mails, browser histories, and search queries, and capture data remotely. As you advance, this book will guide you through implementing forensic techniques on multiple platforms, such as Windows, Linux, and macOS, to demonstrate how to recover valuable information as evidence. Finally, you'll get to grips with presenting your findings efficiently in judicial or administrative proceedings. By the end of this book, you'll have developed a clear understanding of how to acquire, analyze, and present digital evidence like a proficient computer forensics investigator.
Table of Contents (17 chapters)
1
Section 1: Acquiring Evidence
6
Section 2: Investigation
12
Section 3: Reporting

Recovering deleted data

When a file is deleted in the FAT filesystem, the data itself does not get changed. The first character of the directory entry will have it changed to a xE5 and the file allocation table entries are reset to x00. When the filesystem reads the directory entries, and it encounters the xE5, it will skip that entry and start reading from the subsequent entries.

To recover deleted files, we need to reverse the process the filesystem used to delete the files. Remember, it has not changed the file contents; they still physically reside in their assigned clusters. We now need to reverse-engineer the deletion and recreate the file entry and the entries in the file allocation table. To do this, we need to find the first cluster of the file, the size of the file, and the size of the clusters in the volume:

Figure 5.15 – Deleted entry

In the preceding screenshot, we have a directory entry showing that a file has been deleted...