Cybersecurity Ops with bash: Attack, Defend, and Analyze from the Command Line

Description

If you hope to outmaneuver threat actors, speed and efficiency need to be key components of your cybersecurity operations. Mastery of the standard command-line interface (CLI) is an invaluable skill in times of crisis because no other software application can match the CLI’s availability, flexibility, and agility. This practical guide shows you how to use the CLI with the bash shell to perform tasks such as data collection and analysis, intrusion detection, reverse engineering, and administration. Authors Paul Troncone, founder of Digadel Corporation, and Carl Albing, coauthor of bash Cookbook (O’Reilly), provide insight into command-line tools and techniques to help defensive operators collect data, analyze logs, and monitor networks. Penetration testers will learn how to leverage the enormous amount of functionality built into nearly every version of Linux to enable offensive operations. In four parts, security practitioners, administrators, and students will examine: • Foundations: Principles of defense and offense, command-line and bash basics, and regular expressions • Defensive security operations: Data collection and analysis, real-time log monitoring, and malware analysis • Penetration testing: Script obfuscation and tools for command-line fuzzing and remote access Cover Copyright Table of Contents Preface Who This Book Is For Bash or bash Script Robustness Workshops Conventions Used in This Book Using Code Examples O’Reilly Online Learning How to Contact Us Acknowledgments Disclaimer Part I. Foundations Chapter 1. Command-Line Primer The Command Line Defined Why bash? Command-Line Illustrations Running Linux and bash on Windows Git Bash Cygwin Windows Subsystem for Linux Windows Command Prompt and PowerShell Command-Line Basics Commands, Arguments, Built-ins, and Keywords Standard Input/Output/Error Redirection and Piping Running Commands in the Background From Command Line to Script Summary Workshop Chapter 2. Bash Primer Output Variables Positional Parameters Input Conditionals Looping Functions Function Arguments Returning Values Pattern Matching in bash Writing Your First Script—Detecting Operating System Type Summary Workshop Chapter 3. Regular Expressions Primer Commands in Use grep grep and egrep Regular Expression Metacharacters The “.” Metacharacter The “?” Metacharacter The “*” Metacharacter The “+” Metacharacter Grouping Brackets and Character Classes Back References Quantifiers Anchors and Word Boundaries Summary Workshop Chapter 4. Principles of Defense and Offense Cybersecurity Confidentiality Integrity Availability Nonrepudiation Authentication The Attack Life Cycle Reconnaissance Initial Exploitation Establish Foothold Escalate Privileges Internal Reconnaissance Lateral Movement Maintain Presence Complete Mission Summary Part II. Defensive Security Operations with bash Chapter 5. Data Collection Commands in Use cut file head reg wevtutil Gathering System Information Executing a Command Remotely Using SSH Gathering Linux Logfiles Gathering Windows Logfiles Gathering System Information Gathering the Windows Registry Searching the Filesystem Searching by Filename Searching for Hidden Files Searching by File Size Searching by Time Searching for Content Searching by File Type Searching by Message Digest Value Transferring Data Summary Workshop Chapter 6. Data Processing Commands in Use awk join sed tail tr Processing Delimited Files Iterating Through Delimited Data Processing by Character Position Processing XML Processing JSON Aggregating Data Summary Workshop Chapter 7. Data Analysis Commands in Use sort uniq Web Server Access Log Familiarization Sorting and Arranging Data Counting Occurrences in Data Totaling Numbers in Data Displaying Data in a Histogram Finding Uniqueness in Data Identifying Anomalies in Data Summary Workshop Chapter 8. Real-Time Log Monitoring Monitoring Text Logs Log-Based Intrusion Detection Monitoring Windows Logs Generating a Real-Time Histogram Summary Workshop Chapter 9. Tool: Network Monitor Commands in Use crontab schtasks Step 1: Creating a Port Scanner Step 2: Comparing to Previous Output Step 3: Automation and Notification Scheduling a Task in Linux Scheduling a Task in Windows Summary Workshop Chapter 10. Tool: Filesystem Monitor Commands in Use sdiff Step 1: Baselining the Filesystem Step 2: Detecting Changes to the Baseline Step 3: Automation and Notification Summary Workshop Chapter 11. Malware Analysis Commands in Use curl vi xxd Reverse Engineering Hexadecimal, Decimal, Binary, and ASCII Conversions Analyzing with xxd Extracting Strings Interfacing with VirusTotal Searching the Database by Hash Value Scanning a File Scanning URLs, Domains, and IP Addresses Summary Workshop Chapter 12. Formatting and Reporting Commands in Use tput Formatting for Display and Print with HTML Creating a Dashboard Summary Workshop Part III. Penetration Testing with bash Chapter 13. Reconnaissance Commands in Use ftp Crawling Websites Automated Banner Grabbing Summary Workshop Chapter 14. Script Obfuscation Commands in Use base64 eval Obfuscating Syntax Obfuscating Logic Encrypting Cryptography Primer Encrypting the Script Creating the Wrapper Creating Your Own Crypto Summary Workshop Chapter 15. Tool: Command-Line Fuzzer Implementation Summary Workshop Chapter 16. Establishing a Foothold Commands in Use nc Single-Line Backdoors Reverse SSH Bash Backdoor Custom Remote-Access Tool Implementation Summary Workshop Part IV. Security Administration with bash Chapter 17. Users, Groups, and Permissions Commands in Use chmod chown getfacl groupadd setfacl useradd usermod icacls net Users and Groups Creating Linux Users and Groups Creating Windows Users and Groups File Permissions and Access Control Lists Linux File Permissions Windows File Permissions Making Bulk Changes Summary Workshop Chapter 18. Writing Log Entries Commands in Use eventcreate logger Writing Windows Logs Writing Linux Logs Summary Workshop Chapter 19. Tool: System Availability Monitor Commands in Use ping Implementation Summary Workshop Chapter 20. Tool: Software Inventory Commands in Use apt dpkg wmic yum Implementation Identifying Other Software Summary Workshop Chapter 21. Tool: Validating Configuration Implementation Summary Workshop Chapter 22. Tool: Account Auditing Have I Been Pwned? Checking for a Breached Password Checking for a Breached Email Address Batch-Processing Emails Summary Workshop Chapter 23. Conclusion Index About the Authors Colophon