Bandit Level 23 → Level 24 | OverTheWire

Learn linux command by playing Bandit wargame. The Bandit wargame is aimed at absolute beginners. It will teach the basics needed to be able to play other wargames. Below is the solution of Bandit Level 23 → Level 24.

In this level we will learn about corntab files and write our first shell-script in this series.

The passwords are hidden, so you have to find the passwords for next level yourself.

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Bandit Level 23 → Level 24

Level Goal

A program is running automatically at regular intervals from cron, the time-based job scheduler. Look in /etc/cron.d/ for the configuration and see what command is being executed.

NOTE: This level requires you to create your own first shell-script. This is a very big step and you should be proud of yourself when you beat this level!

NOTE 2: Keep in mind that your shell script is removed once executed, so you may want to keep a copy around…

Commands you may need to solve this level

cron, crontab, crontab(5) (use “man 5 crontab” to access this)

Solution :

Command to connect remote host : ssh bandit23@bandit.labs.overthewire.org -p 2220 password is **** .

Execute these commands to know the content of crontab file and then content of the script file.

cd /etc/cron.d/
ls
cat cronjob_bandit24
cat /usr/bin/cronjob_bandit24.sh

The script in cronjob_bandit24.sh is :

#!/bin/bash
myname=$(whoami)
cd /var/spool/$myname
echo "Executing and deleting all scripts in /var/spool/$myname:"
for i in * .*;
do
    if [ "$i" != "." -a "$i" != ".." ];
    then
	echo "Handling $i"
	timeout -s 9 60 ./$i
	rm -f ./$i
    fi
done

The command cd /vars/pool/$myname will change to bandit24 directory and then all scripts in directory bandit24 will be executed and then deleted. This is done in every 60 seconds as timeout is provided.

Bandit Level 23 24

So if we put our script in /var/spool/bandit24 then it will be executed and then deleted. So we will write our script such that it will output password for next level.

We will create a directory pcdir123 in /tmp directory and change the permissions to readable, writeable and executable for pcdir123. (This is very important). The command are:

mkdir /tmp/pcdir123
chmod 777 pcdir123

Bandit Level 23 24

Now create a script file pass24script.sh in /tmp/pcdir123 which will contain our script. The script is

#!/bin/sh
cat /etc/bandit_pass/bandit24 > /tmp/pcdir123/pass24file

pass24script.sh is not executable, so make it executable for all users using command chmod 777 pass24script.

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Copy this script in /var/spool/bandit/24 using command cp pass24script.sh /var/spool/bandit24

When new minute starts, file pass24file is produced with password for the next level if the directory pcdir123 has write permission enabled. The password is **** .

Bandit Level 23 24