Debian Server 12 - adding user to sudoers

sudo is a command-line utility that allows trusted users to run commands as another user, by default root. This tutorial shows two ways to grant sudo privileges to a user.

1. Step -On my VM Debian Server I had to install the sudo utility first as root user I ran

   apt install sudo

2. Step is to add user you sudoers file. To do so you need to as root user run visudo and at the end of file add

   username ALL=(ALL) NOPASSWD:ALL

3. Step is to add user to the sudo group, again as root you run

   usermod -aG sudo username

4. Step you can now check if you can use sudo command as user you created before and if you followed those steps you should be able to run commands as trusted user

TryHackMe - Year of the Rabbit - writeup

Year of the Rabbit is the beginer friendly CTF room on TryHackMe.com. How ever i strongly suggest that this isnt your very first CTF room. Because this one is pretty long and not so straight forward as you would suspect from easy room. Here is my "journey" through the VM we need to hack in and

1. step

As usually I started with nmap scan:

nmap -sS VM_IP

Output looks promissing with open ftp, ssh and http port.
I tried if ftp might allow us anonymous log in but without luck it doesnt allow. We will return to the ftp later.
2. step

In this step we will run our friend gobuster.

gobuster dir -u http://VM_IP -w /usr/share/wordlists/dirb/common.txt -x php,txt,html

Output directs us to the /assets folder where we find 2 files.
3. step

Well we got some text and a video. The text suggest that hint is in the video so i went for that but no luck. I tried looking around the web for hint and suggestion was to use burp suite. We use it to intercept the get request for page /sup3r_s3cr3t_fl4g.php in response we find the hidden folder.
4. step

Open the hidden folder we got in previous step we find picture of the girl. Hmm what could we do with it maybe some meta data.

strings hot_babe.png

Voila we get list of possible password and username for FTP access.
5. step

We use hydra tool:

hydra -l ftpuser - P possible_pass.txt ftp:/vm_ip

Hydra will run fast because of short list and you get log in to the ftp with username and password:

ftp VM_IP

We are prompted for credentials. After login we use ls and we see Eli's_Creds.txt. I have downloaded filed to attackbox:

get Eli's_Creds.txt

6. step

I have opened file on attackbox at first file looks like jibrish but I think I saw once this before.
I have looked around the web for brainfuck language. I have confirmed that this is brainfuck and I used this decoder
This one gave us ssh credentials.

ssh username@VM_IP

We enter password we got with decoded and the login we get hint were to look for flag? or soemthing else? we have found another credendetials.

su another_username

After logged in new account I checked home folder of user where you find the user.txt flag.
7. step

Ok we got user flag, lets try to escalate priviliges. We check if we can run any command as root user.

sudo -l

From output I saw you can run vi program. I headed over to the GTFObins and see what command will help us to get the root access.

sudo -u#-1 /usr/bin/vi /home/gwendoline/user.txt

then we ctrl + c and we type in !/bin/sh and voila we have root access.

cd /root

ls

cat root.txt

I hope anyone who gets stuck finds it helpful
AudiTTRSi

How to change default ssh login banner

To create a cool ASCII art banner for your server, first start off by going here:

ASCII art creator/

To change the message displayed before login, edit /etc/ssh/sshd_config :

sudo vim /etc/ssh/sshd_config

and add (or uncomment) the line:

Banner /etc/banner

/etc/banner can be whatever file you want. Then edit /etc/banner

sudo vim /etc/banner

You’ll probably need to restart sshd before your changes take effect:

sudo /etc/init.d/ssh restart

To change the message displayed after login, edit /etc/motd :

sudo vim /etc/motd

and enter the message you want to display.