Lab 2 - Shellshock Attack Lab.pdf - CS421 Information Security lab 2 Shellshock Attack Lab Table of Contents OVERVIEW 1 TASK 1 EXPERIMENTING WITH BASH

Lab 2 - Shellshock Attack Lab.pdf - CS421 Information...

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CS421 Information Security lab 2 Page 1 of 5 Shellshock Attack Lab Table of Contents OVERVIEW ........................................................................................................................................... 1 TASK 1: EXPERIMENTING WITH BASH FUNCTION ................................................................................. 2 TASK 2: SETTING UP CGI PROGRAMS ................................................................................................... 2 TASK 3: PASSING DATA TO BASH VIA ENVIRONMENT VARIABLE .......................................................... 3 TASK 4: LAUNCHING THE SHELLSHOCK ATTACK .................................................................................... 3 TASK 5: GETTING A REVERSE SHELL VIA SHELLSHOCK ATTACK .............................................................. 3 TASK 6: USING THE PATCHED BASH ..................................................................................................... 4 G UIDELINES : C REATING R EVERSE S HELL ........................................................................................................ 4 SUBMISSION ........................................................................................................................................ 5 Overview On September 24, 2014, a severe vulnerability in Bash was identified. Nicknamed Shellshock, this vulnerability can exploit many systems and be launched either remotely or from a local machine. In this lab, students need to work on this attack, so they can understand the Shellshock vulnerability. The learning objective of this lab is for students to get a first-hand experience on this interesting attack, understand how it works, and think about the lessons that we can get out of this attack. This lab covers the following topics: • Shellshock • Environment variables • Function definition in Bash • Apache and CGI programs Lab environment. This lab has been tested on our pre-built Ubuntu 16.04 VM, which can be downloaded from the SEED website. . Download the June 2019 version of ubuntu 16.04
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CS421 Information Security lab 2 Page 2 of 5 Lab Tasks Task 1: Experimenting with Bash Function The Bash program in Ubuntu 16.04 has already been patched, so it is no longer vulnerable to the Shellshock attack. For the purpose of this lab, we have installed a vulnerable version of Bash inside the /bin folder; its name is bash shellshock. We need to use this Bash in our task. Please run this vulnerable version of Bash like the following and then design an experiment to verify whether this Bash is vulnerable to the Shellshock attack or not. $ /bin/bash_shellshock Try the same experiment on the patched version of bash (/bin/bash) and report your observations. Task 2: Setting up CGI programs In this lab, we will launch a Shellshock attack on a remote web server. Many web servers enable CGI, which is a standard method used to generate dynamic content on Web pages and Web applications. Many CGI programs are written using shell scripts. Therefore, before a CGI program is executed, a shell program will be invoked first, and such an invocation is triggered by a user from a remote computer. If the shell program is a vulnerable Bash program, we can exploit the Shellshock vulnerable to gain privileges on the server.
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