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Practical Linux Security Cookbook

You're reading from   Practical Linux Security Cookbook Secure your Linux machines and keep them secured with the help of exciting recipes

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Product type Paperback
Published in Apr 2016
Publisher Packt
ISBN-13 9781785286421
Length 276 pages
Edition 1st Edition
Tools
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Authors (2):
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Michael A Lindner Michael A Lindner
Author Profile Icon Michael A Lindner
Michael A Lindner
Tajinder Kalsi Tajinder Kalsi
Author Profile Icon Tajinder Kalsi
Tajinder Kalsi
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Toc

Table of Contents (12) Chapters Close

Preface 1. Linux Security Problems 2. Configuring a Secure and Optimized Kernel FREE CHAPTER 3. Local Filesystem Security 4. Local Authentication in Linux 5. Remote Authentication 6. Network Security 7. Security Tools 8. Linux Security Distros 9. Patching a Bash Vulnerability 10. Security Monitoring and Logging Index

Understanding the bash vulnerability through Shellshock


Shellshock, or Bashdoor, is a vulnerability that's used in most versions of the Linux and Unix operating systems. It was discovered on September 12, 2014, and it affects all the distributions of Linux using a bash shell. The Shellshock vulnerability makes it possible to execute commands remotely using environment variables.

Getting Ready

To understand Shellshock, we need a Linux system that uses a version of bash prior to 4.3, which is vulnerable to this bug.

How to do it…

In this section, we will take a look at how to set up our system to understand the internal details of the Shellshock vulnerability:

  1. The first step is to check the version of bash on the Linux system so that we can figure out whether our system is vulnerable to Shellshock. To check the version of bash, we run this command:

    Bash versions from 4.3 and onwards have been reported to be vulnerable to Shellshock. For our example, we are using the Ubuntu 12.04 LTS desktop version...

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