Wednesday, June 25, 2014

Book Review: Penetration Testing with the Bash Shell

This post is my review of the Packt Publishing book Penetration Testing with the Bash shell by Keith Makan. I think it's important to emphasize its subtitle: "Make the most of the Bash shell and Kali Linux's command-line-based security assessment tools." As the main title and sub-title suggest, this book is about penetration testing with Bash using the Kali Linux. The book has approximately 125 pages covering 5 chapters.

The Preface of Penetration Testing with the Bash shell begins with an articulation of why it is important for penetration testers to be familiar with command-line tools. The Preface also provides brief summaries of each of the five chapters in the book and some of the command-line tools covered in each chapter.

Under the "What you need for this book" section of Penetration Testing with the Bash shell's Preface, Makan writes, "The only software requirement for this book is the Kali Linux operating system, which you can download in the ISO format from" You don't necessarily need to use Kali Linux as many of the bash examples and described command-line tools are also available with or for other Linux distributions. The "Who this book is for" section of the Preface states, "Command line hacking is a book for anyone interested in learning how to wield their Kali Linux command lines to perform effective penetration testing."

Chapter 1: Getting to Know Bash

The initial chapter explains that "throughout the book, the bash environment or the host operating system that will be discussed will be Kali Linux" and that "Kali Linux is a distribution adapted from Debian." The chapter then goes onto explain with text and examples Bash concepts such as man pages and bash commands such cd, ls, pwd, and find. The chapter also describes using Linux redirection (output and input) and pipes before concluding with a discussion of grep and regular expressions. As the author suggests, this chapter could be generally be skipped by developers familiar with Linux, but would be must-read information for those new to Linux. Although Kali Linux is used for the examples, I didn't see anything in this initial chapter that seemed specific to Kali Linux.

Chapter 2: Customizing Your Shell

The second chapter of Penetration Testing with the Bash shell begins with coverage of terminal control sequences to change appearance of text in the terminal. The chapter builds upon this information to demonstrate customization of the terminal prompt. Chapter 2 also introduces aliases, customizing command history, and customizing tab completion. Like the first chapter, this second chapter covers additional general Bash concepts rather than specifics of penetration testing.

Chapter 3: Network Reconnaissance

Chapter 3 of Penetration Testing with the Bash shell transitions from coverage of Linux and bash to "move on to using the shell and the Kali Linux command-line utilities to collect information about the networks you find yourself in." The chapter examines tools such as whois, dig, dnsmap, Nmap, and arping.

Chapter 4: Exploitation and Reverse Engineering

Penetration Testing with the Bash shell's fourth chapter focuses on reverse engineering and tools that "may enable you to discover memory corruption, code injection, and general data- or file-handling flaws that may be used to instantiate arbitrary code execution vulnerabilities." Tools covered in this chapter include Metasploit (including command-line msfcli, mixing msfcli with bash commands and other command line tools, msfpayload, Meterpreter), objdump, and GDB.

Chapter 5: Network Exploitation and Monitoring

The fifth and final chapter of Penetration Testing with the Bash shell focuses "on the network exploitation available in Kali Linux and how to take advantage of it in the modern bash shell environment." This relatively longer chapter begins with discussion of "Media Access Control (MAC) spoofing" and "Address Resolution Protocol (ARP) abuse." The chapter looks at tools such as macchangeer, ifconfig, arpspoof.

Chapter 5 describes man-in-the-middle (MITM) attacks and provides a detailed introduction to ettercap. The chapter also explains server interrogation and describes tools for Simple Network Management Protocol (SNMP) interrogation (snmpwalk and Metasploit's snmp_enum and snmp_login) and for Simple Mail Transfer Protocol (SMTP) interrogation (smtp-user-enum).

There is a section in Chapter 5 on brute force authentication that demonstrates use of Medusa. The section of Chapter 5 on traffic filtering demonstrates use of TCPDump. SSLyze is demonstrated as a tool for "assess[ing] SSL/TLS implementations" and SkipFish and Arachni are demonstrated as tools for scanning web pages and web applications for vulnerabilities.

General Observations
  • The electronic version of Penetration Testing with the Bash shell that I reviewed included numerous colored screen snapshots.
  • I liked the "Further Reading" sections at the end of each chapter that provided links to online information with more detail about subjects covered in the chapter.
  • The first two chapters of Penetration Testing with the Bash shell have very little information specific to penetration testing but provide an overview of some bash features used in later chapters. The third, fourth, and fifth chapters are heavily focused on penetration testing and build upon the bash basics covered in the first two chapters.
  • Penetration Testing with the Bash shell provides background information on various security and assessment concepts as its illustrates the tools available that are related to those concepts.
  • There are some awkward sentence structures in Penetration Testing with the Bash shell and several of the sentences are too long for my taste (especially early in the book), but I was generally able to make out the intent of the writing. An example of the occasional awkward but understandable text is on the first page of the first chapter: "Why are discussing the bash shell?"
  • Although this book does mention Kali Linux specifically and frequently, the majority of the described tools are available as built-in tools or as tools that can be installed separately with other flavors of Linux. With no or just a a bit of effort, one could run the examples in different Linux implementations. It's also worth pointing out that the author repeatedly mentions that several commands runs with no special effort in Kali Linux because things are run as root. In other Linux implementations, you may need to use sudo to apply these tools.
  • Although I am fairly familiar with bash, I still learned a few new things from the first two chapters (primarily the second chapter). I am far less experienced with penetration testing and learned quite a bit from the other three chapters.

Penetration Testing with the Bash shell: Make the most of the Bash shell and Kali Linux's command-line-based security assessment tools outlines how bash in general and Kali Linux in particular provide command-line security assessment tools. The book introduces the tools and how to apply them and explains security-related concepts along the way.

No comments: