Complete OvertheWire Bandit Walkthrough

This article provides the complete OvertheWire Bandit Walkthrough of Wargame Challenge. #centlinux #linux #overthewire

What is OvertheWire Wargame?

A wargame is a cyber-security challenge and mind sport in which competitors must exploit or defend a vulnerability in a system or application, or gain or prevent access to a computer system. Bandit Wargame is a popular challenge for Cyber Security and Linux experts to test/improve their relevant skills.

OvertheWire provides a live Linux server to play Bandit wargame. Bandit wargame consists of 33 challenges. Each challenge will test your Linux and penetration skills.

We strongly recommend that every Linux system admin or Cyber Security personnel to try this challenge. We guarantees that Bandit Challenge will improve your knowledge and skills related to Linux and Ethical Hacking.

How Linux Works, 2nd Edition: What Every Superuser Should Know (PAID LINK)(by Brian Ward) is a must have reference book, if you want to understand the nuts and bolts of Linux operating system.

Note: We have written this article to help the readers to get help, if they have stuck at some level in the Bandit wargame. However, we strongly recommend that, you should only read OvertheWire Bandit Walkthrough in case you didn’t find a way to move on in this game. Otherwise, try to solve the Bandit wargame challenges on your own, it will surely improve your skills.

OvertheWire Bandit Walkthrough: Level 0:

Goal:

The goal of this level is for you to log into the game using SSH. The host to which you need to connect is bandit.labs.overthewire.org, on port 2220. The username is bandit0 and the password is bandit0. Once logged in, go to the Level 1 page to find out how to beat Level 1.

Solution:

It is not a challenge!

In this level, we are provided the SSH connection settings and the initial user to login to the OvertheWire server and start Bandit wargame.

OvertheWire Bandit Walkthrough: Level 0-1:

Goal:

The password for the next level is stored in a file called readme located in the home directory. Use this password to log into bandit1 using SSH. Whenever you find a password for a level, use SSH (on port 2220) to log into that level and continue the game.

Solution:

Login to OvertheWire server as bandit0 user by using a ssh tool such as PuTTY.

Display the contents of the readme file.

bandit0@bandit:~$ cat readme
boJ9jbbUNNfktd78OOpsqOltutMc3MY1

The password for the bandit1 user has been found.

OvertheWire Bandit Walkthrough: Level 1-2:

Goal:

The password for the next level is stored in a file called – located in the home directory

Solution:

Password is located in ‘-‘ file. But to display its content is a little tricky task, because regular syntax do not work.

Therefore, we need to provide either the absolute or relative path to open this file.

bandit1@bandit:~$ cat /home/bandit1/-
CV1DtqXWVFXTvM2F0k09SHz0YwRINYA9

We have got the password of bandit2 user.

OvertheWire Bandit Walkthrough: Level 2-3:

Goal:

The password for the next level is stored in a file called spaces in this filename located in the home directory

Solution:

We can print the contents of the file as follows.

bandit2@bandit:~$ cat spaces in this filename
UmHadQclWmgdLOKQ3YNgjWxGoRMb5luK

Password of bandit3 user has been retrieved.

OvertheWire Bandit Walkthrough: Level 3-4:

Goal:

The password for the next level is stored in a hidden file in the inhere directory.

Solution:

List the files available in inhere directory.

bandit3@bandit:~$ ls -al inhere/
total 12
drwxr-xr-x 2 root    root    4096 Oct 16  2018 .
drwxr-xr-x 3 root    root    4096 Oct 16  2018 ..
-rw-r----- 1 bandit4 bandit3   33 Oct 16  2018 .hidden

Print the contents of the one and only file in inhere directory.

bandit3@bandit:~$ cat inhere/.hidden
pIwrPrtPN36QITSp3EQaw936yaFoFgAB

OvertheWire Bandit Walkthrough: Level 4-5:

Goal:

The password for the next level is stored in the only human-readable file in the inhere directory. Tip: if your terminal is messed up, try the “reset” command.

Solution:

List the contents of inhere directory.

bandit4@bandit:~$ ls inhere/
-file00  -file02  -file04  -file06  -file08
-file01  -file03  -file05  -file07  -file09

To find the human-readable file, we can use file command to check type of each file as follows.

bandit4@bandit:~$ file inhere/*
inhere/-file00: data
inhere/-file01: data
inhere/-file02: data
inhere/-file03: data
inhere/-file04: data
inhere/-file05: data
inhere/-file06: data
inhere/-file07: ASCII text
inhere/-file08: data
inhere/-file09: data

-file07 is our required file. Print its content now to retrieve the password for next level.

bandit4@bandit:~$ cat inhere/-file07
koReBOKuIDDepwhWk7jZC0RTdopnAYKh

Password of bandit5 user has been located.

OvertheWire Bandit Walkthrough: Level 5-6:

Goal:

The password for the next level is stored in a file somewhere under the inhere directory and has all of the following properties:

• human-readable
• 1033 bytes in size
• not executable

Solution:

Find the files of 1033 bytes in size within inhere directory.

bandit5@bandit:~$ find ./inhere -size 1033c ! -executable
./inhere/maybehere07/.file2

There is only one file of this size. Print its content now.

bandit5@bandit:~$ cat inhere/maybehere07/.file2
DXjZPULLxYr17uwoI01bNLQbtFemEgo7

We have found the password of bandit6 user.

OvertheWire Bandit Walkthrough: Level 6-7:

Goal:

The password for the next level is stored somewhere on the server and has all of the following properties:

• owned by user bandit7
• owned by group bandit6
• 33 bytes in size

Solution:

Scan the root (/) directory to find the files with required conditions.

bandit6@bandit:~$ find / -user bandit7 -group bandit6 -size 33c 2> /dev/null
/var/lib/dpkg/info/bandit7.password

Passwordfile has been found. Print its content now and retrieve the password for next level.

bandit6@bandit:~$ cat /var/lib/dpkg/info/bandit7.password
HKBPTKQnIay4Fw76bEy8PVxKEDQRKTzs

OvertheWire Bandit Walkthrough: Level 7-8:

Goal:

The password for the next level is stored in the file data.txt next to the word millionth

Solution:

Use grep command to find the row containing word ‘millionth’.

bandit7@bandit:~$ grep millionth data.txt
millionth       cvX2JJa4CFALtqS87jk27qwqGhBM9plV

Password of bandit8 user is written next to the ‘millionth’ word. Use this password to login as bandit8 user.

OvertheWire Bandit Walkthrough: Level 8-9:

Goal:

The password for the next level is stored in the file data.txt and is the only line of text that occurs only once

Solution:

To extract the following line of text, we need to combine multiple commands together as follows.

bandit8@bandit:~$ sort data.txt | uniq -c | sort | tail -1
      1 UsvVyFSfZZWbi6wgC7dAFyFuR6jQQUhR

We have located the password for next level.

OvertheWire Bandit Walkthrough: Level 9-10:

Goal:

The password for the next level is stored in the file data.txt in one of the few human-readable strings, beginning with several ‘=’ characters.

Solution:

Use the strings command to list down the human-readable strings in data.txt file, then use a grep command to filter strings that begin with several ‘=’ characters.

bandit9@bandit:~$ strings data.txt | grep '^==='
========== password
========== isa
========== truKLdjsbJ5g7yyJ2X2R0o3a5HQJFuLk

OvertheWire Bandit Walkthrough: Level 10-11:

Goal:

The password for the next level is stored in the file data.txt, which contains base64 encoded data

Solution:

Use base64 command to decode the text in data.txt file.

bandit10@bandit:~$ base64 -d data.txt
The password is IFukwKGsFW8MOq3IRFqrxE1hxTNEbUPR

Use this password to login to next level.

OvertheWire Bandit Walkthrough: Level 11-12:

Goal:

The password for the next level is stored in the file data.txt, where all lowercase (a-z) and uppercase (A-Z) letters have been rotated by 13 positions

Solution:

Text in data.txt file has been encrypted using ROT13 algorithm. We can use the tr command to decrypt it.

bandit11@bandit:~$ cat data.txt | tr 'A-Ma-mN-Zn-z' 'N-Zn-zA-Ma-m'
The password is 5Te8Y4drgCRfCx8ugdwuEX8KFC6k2EUu

OvertheWire Bandit Walkthrough: Level 12-13:

Goal:

The password for the next level is stored in the file data.txt, which is a hexdump of a file that has been repeatedly compressed. For this level it may be useful to create a directory under /tmp in which you can work using mkdir. For example: mkdir /tmp/myname123. Then copy the datafile using cp, and rename it using mv (read the manpages!)

Solution:

Create a temporary directory and copy data.txt file therein.

bandit12@bandit:~$ mkdir /tmp/bandit12_ahmer
bandit12@bandit:~$ cd /tmp/bandit12_ahmer
bandit12@bandit:/tmp/bandit12_ahmer$ cp ~/data.txt .

It is given that the data.txt file is the hexdump of another file. Therefore, use xxd command with reverse flag to obtain the original file.

bandit12@bandit:/tmp/bandit12_ahmer$ xxd -r data.txt > data1

Check the file type of the data1 file.

bandit12@bandit:/tmp/bandit12_ahmer$ file data1
data1: gzip compressed data, was "data2.bin", last modified: Tue Oct 16 12:00:23 2018, max compression, from Unix

data1 is a gzip compressed file, therefore rename it properly and then decompress by using gzip command.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data1 data2.tar.gz
bandit12@bandit:/tmp/bandit12_ahmer$ gzip -d data2.tar.gz

After decompression, we got data2.tar file. Again check its file type.

bandit12@bandit:/tmp/bandit12_ahmer$ file data2.tar
data2.tar: bzip2 compressed data, block size = 900k

data2.tar is a bzip2 compressed file, therefore rename it properly and then decompress by using bzip2 command.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data2.tar data3.tar.bz2
bandit12@bandit:/tmp/bandit12_ahmer$ bzip2 -d data3.tar.bz2

We got data3.tar file after decompression. Check its file type again.

bandit12@bandit:/tmp/bandit12_ahmer$ file data3.tar
data3.tar: gzip compressed data, was "data4.bin", last modified: Tue Oct 16 12:00:23 2018, max compression, from Unix

data3.tar is a gzip compressed file, therefore rename and extract it.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data3.tar data4.tar.gz
bandit12@bandit:/tmp/bandit12_ahmer$ gzip -d data4.tar.gz

We have data4.tar file now. Check its file type.

bandit12@bandit:/tmp/bandit12_ahmer$ file data4.tar
data4.tar: POSIX tar archive (GNU)

data4.tar is a tar archive, therefore, we can extract it using tar command.

bandit12@bandit:/tmp/bandit12_ahmer$ tar xf data4.tar

We get data5.bin from tar archive. Check its file type again.

bandit12@bandit:/tmp/bandit12_ahmer$ file data5.bin
data5.bin: POSIX tar archive (GNU)

data4.bin is a tar archive. Therefore, rename and extract it.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data5.bin data5.tar
bandit12@bandit:/tmp/bandit12_ahmer$ tar xf data5.tar

We get data6.bin from tar archive. Check it file type again.

bandit12@bandit:/tmp/bandit12_ahmer$ file data6.bin
data6.bin: bzip2 compressed data, block size = 900k

This time it is a bzip2 compressed file. Rename and extract it accordingly.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data6.bin data6.tar.bz2
bandit12@bandit:/tmp/bandit12_ahmer$ bzip2 -d data6.tar.bz2

We get data6.tar from bzip2 archive. Check its content type.

bandit12@bandit:/tmp/bandit12_ahmer$ file data6.tar
data6.tar: POSIX tar archive (GNU)

data6.tar is a tar archive, therefore extract it using tar command.

bandit12@bandit:/tmp/bandit12_ahmer$ tar xf data6.tar

This time we have data8.bin from tar archive. Check its file type.

bandit12@bandit:/tmp/bandit12_ahmer$ file data8.bin
data8.bin: gzip compressed data, was "data9.bin", last modified: Tue Oct 16 12:00:23 2018, max compression, from Unix

data8.bin is a gzip compressed file. Therefore, rename and extract it as follows.

bandit12@bandit:/tmp/bandit12_ahmer$ mv data8.bin data8.tar.gz
bandit12@bandit:/tmp/bandit12_ahmer$ gzip -d data8.tar.gz

We got data8.tar from gzip archive. Check its file type.

bandit12@bandit:/tmp/bandit12_ahmer$ file data8.tar
data8.tar: ASCII text

Finally, we get a text file. Print its contents now.

bandit12@bandit:/tmp/bandit12_ahmer$ cat data8.tar
The password is 8ZjyCRiBWFYkneahHwxCv3wb2a1ORpYL

We have found the password of bandit13 user.

OvertheWire Bandit Walkthrough: Level 13-14:

Goal:

The password for the next level is stored in /etc/bandit_pass/bandit14 and can only be read by user bandit14. For this level, you don’t get the next password, but you get a private SSH key that can be used to log into the next level. Note: localhost is a hostname that refers to the machine you are working on

Solution:

This time you will get a private SSH key, that can be used to login as bandit14 user without any password.

bandit13@bandit:~$ ls
sshkey.private

Use ssh command to login as bandit14 user by using this private SSH key.

bandit13@bandit:~$ ssh bandit14@localhost -i sshkey.private

After successful login, password of bandit14 user is now accessible. Obtain it from the file /etc/bandit_pass/bandit14.

bandit14@bandit:~$ cat /etc/bandit_pass/bandit14
4wcYUJFw0k0XLShlDzztnTBHiqxU3b3e

OvertheWire Bandit Walkthrough: Level 14-15:

Goal:

The password for the next level can be retrieved by submitting the password of the current level to port 30000 on localhost.

Solution:

To obtain the password of bandit15, we need to send the password of bandit14 at port 30000.

bandit14@bandit:~$ echo "4wcYUJFw0k0XLShlDzztnTBHiqxU3b3e" | nc localhost 30000 
Correct!
BfMYroe26WYalil77FoDi9qh59eK5xNr

OvertheWire Bandit Walkthrough: Level 15-16:

Goal:

The password for the next level can be retrieved by submitting the password of the current level to port 30001 on localhost using SSL encryption.

Helpful note: Getting “HEARTBEATING” and “Read R BLOCK”? Use -ign_eof and read the “CONNECTED COMMANDS” section in the manpage. Next to ‘R’ and ‘Q’, the ‘B’ command also works in this version of that command…

Solution:

To obtain password of bandit16 user, we need to send password of bandit15 user at port 30001 in encrypted form.

bandit15@bandit:~$ echo "BfMYroe26WYalil77FoDi9qh59eK5xNr" | openssl s_client -connect localhost:30001 -ign_eof
CONNECTED(00000003)

---
Correct!
cluFn7wTiGryunymYOu4RcffSxQluehd

closed

We have received the password of bandit16 user.

OvertheWire Bandit Walkthrough: Level 16-17:

Goal:

The credentials for the next level can be retrieved by submitting the password of the current level to a port on localhost in the range 31000 to 32000. First find out which of these ports have a server listening on them. Then find out which of those speak SSL and which don’t. There is only 1 server that will give the next credentials, the others will simply send back to you whatever you send to it.

Solution:

Find the open ports between range 31000-32000.

bandit16@bandit:~$ nmap localhost -p 31000-32000

Starting Nmap 7.40 ( https://nmap.org ) at 2020-03-25 08:37 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00027s latency).
Not shown: 999 closed ports
PORT      STATE    SERVICE
31518/tcp filtered unknown
31790/tcp open     unknown

Nmap done: 1 IP address (1 host up) scanned in 1.24 seconds

31790/tcp is our target port. Therefore, send password of bandit16 user at port 31790.

bandit16@bandit:~$ echo "cluFn7wTiGryunymYOu4RcffSxQluehd" | openssl s_client -connect localhost:31790 -ign_eof
CONNECTED(00000003)
---
Correct!
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

closed

This time we don’t get the password of bandit17 user but instead we have the private SSH key to login without password.

We need to save this private SSH key in a text file. Therefore, create a temporary directory.

bandit16@bandit:~$ mkdir /tmp/bandit16_ahmer
bandit16@bandit:~$ cd /tmp/bandit16_ahmer

Create a file using nano editor and copy/paste the private SSH key therein.

bandit16@bandit:~$ nano /tmp/bandit16_ahmer/sshkey.txt

Change permissions of this file.

bandit16@bandit:~$ chmod 600 /tmp/bandit16_ahmer/sshkey.txt

Now, we can login by using this SSH key as follows.

bandit16@bandit:~$ ssh bandit17@localhost -i /tmp/bandit16_ahmer/sshkey.txt

We have been successfully login as bandit17 user. We can now get the password from /etc/bandit_pass directory.

bandit17@bandit:~$ cat /etc/bandit_pass/bandit17
xLYVMN9WE5zQ5vHacb0sZEVqbrp7nBTn

OvertheWire Bandit Walkthrough: Level 17-18:

Goal:

There are 2 files in the home directory: passwords.old and passwords.new. The password for the next level is in passwords.new and is the only line that has been changed between passwords.old and passwords.new

NOTE: if you have solved this level and see ‘Byebye!’ when trying to log into bandit18, this is related to the next level, bandit19

Solution:

Check the difference in password.new and password.old files.

bandit17@bandit:~$ diff passwords.old passwords.new
42c42
< hlbSBPAWJmL6WFDb06gpTx1pPButblOA
---
> kfBf3eYk5BPBRzwjqutbbfE887SVc5Yd

We can now login as bandit18 user using password “kfBf3eYk5BPBRzwjqutbbfE887SVc5Yd”.

OvertheWire Bandit Walkthrough: Level 18-19:

Goal:

The password for the next level is stored in a file readme in the home directory. Unfortunately, someone has modified .bashrc to log you out when you log in with SSH.

Solution:

When we try to login as bandit18 user, the session ends immediately.

bandit17@bandit:~$ ssh bandit18@localhost
...
Byebye !
Connection to localhost closed.

Login as bandit18 user and bypass the pseudo session allocation.

bandit16@bandit:~$ ssh bandit18@localhost -T

We have been successfully login as bandit16 user and bypass the .bashrc file.

Check readme file and obtain the password of bandit19 user.

cat readme
IueksS7Ubh8G3DCwVzrTd8rAVOwq3M5x

OvertheWire Bandit Walkthrough: Level 19-20:

Goal:

To gain access to the next level, you should use the setuid binary in the home directory. Execute it without arguments to find out how to use it. The password for this level can be found in the usual place (/etc/bandit_pass), after you have used the setuid binary.

Solution:

In this question, you have been provided a setuid binary command that executes commands as bandit20 user.

To check the usage, execute it without any argument.

bandit19@bandit:~$ ./bandit20-do
Run a command as another user.
  Example: ./bandit20-do id

We know the location of the password therefore pass the command to display its contents to bandit20-do script.

bandit19@bandit:~$ ./bandit20-do cat /etc/bandit_pass/bandit20
GbKksEFF4yrVs6il55v6gwY5aVje5f0j

We have found the password of bandit20 user.

OvertheWire Bandit Walkthrough: Level 20-21:

Goal:

There is a setuid binary in the home directory that does the following: it makes a connection to localhost on the port you specify as a commandline argument. It then reads a line of text from the connection and compares it to the password in the previous level (bandit20). If the password is correct, it will transmit the password for the next level (bandit21).

NOTE: Try connecting to your own network daemon to see if it works as you think

Solution:

We have a setuid binary command in this question. Execute this command without any argument.

bandit20@bandit:~$ ./suconnect
Usage: ./suconnect <portnumber>

As given in the challenge, this program will connect to the given port on localhost using TCP. If it receives the correct password from the other side, the next password is transmitted back.

Start a netcat listener on port 55555 that will return the bandit20 password to connecting program.

bandit20@bandit:~$ echo GbKksEFF4yrVs6il55v6gwY5aVje5f0j | nc -l localhost -p 55555 &
[1] 25315

Now execute the suconnect script to connect with port 55555.

bandit20@bandit:~$ ./suconnect 55555
Read: GbKksEFF4yrVs6il55v6gwY5aVje5f0j
Password matches, sending next password
gE269g2h3mw3pwgrj0Ha9Uoqen1c9DGr

We have got the password of bandit21 user.

OvertheWire Bandit Walkthrough: Level 21-22:

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.

Solution:

Let’s have a look, what is available in /etc/cron.d directory.

bandit21@bandit:~$ ls /etc/cron.d
atop  cronjob_bandit22  cronjob_bandit23  cronjob_bandit24

Our core interest is bandit22 user this time, therefore check what is running by the cronjob_bandit22 schedule.

bandit21@bandit:~$ cat /etc/cron.d/cronjob_bandit22
@reboot bandit22 /usr/bin/cronjob_bandit22.sh &> /dev/null
* * * * * bandit22 /usr/bin/cronjob_bandit22.sh &> /dev/null

Execute cronjob_bandit22.sh script and observe the output.

bandit21@bandit:~$ /usr/bin/cronjob_bandit22.sh
chmod: changing permissions of '/tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv': Operation not permitted
/usr/bin/cronjob_bandit22.sh: line 3: /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv: Permission denied

Check the contents of /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv file.

bandit21@bandit:~$ cat /tmp/t7O6lds9S0RqQh9aMcz6ShpAoZKF7fgv
Yk7owGAcWjwMVRwrTesJEwB7WVOiILLI

We have found the password of bandit22 user.

OvertheWire Bandit Walkthrough: Level 22-23:

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: Looking at shell scripts written by other people is a very useful skill. The script for this level is intentionally made easy to read. If you are having problems understanding what it does, try executing it to see the debug information it prints.

Solution:

Just like previous challenge, there is also a cron job. Lets have a look into /etc/cron.d directory.

bandit22@bandit:~$ ls /etc/cron.d
atop  cronjob_bandit22  cronjob_bandit23  cronjob_bandit24

Our concern is the password of bandit23 user, therefore cronjob_bandit23 might be useful for us.

bandit22@bandit:~$ cat /etc/cron.d/cronjob_bandit23
@reboot bandit23 /usr/bin/cronjob_bandit23.sh  &> /dev/null
* * * * * bandit23 /usr/bin/cronjob_bandit23.sh  &> /dev/null

We have located the script, let’s have a look into its code.

bandit22@bandit:~$ cat /usr/bin/cronjob_bandit23.sh
#!/bin/bash

myname=$(whoami)
mytarget=$(echo I am user $myname | md5sum | cut -d ' ' -f 1)

echo "Copying passwordfile /etc/bandit_pass/$myname to /tmp/$mytarget"

cat /etc/bandit_pass/$myname > /tmp/$mytarget

This script is copying the passwordfile of the login user to a temporary file in /tmp directory. The filename of temporary file is generated by using the username of the current user.

We are executing the following code segment from this script after replacing the $mytarget variable with a literal bandit23. This way we will obtain the name of the file that contains the password of bandit23 user.

bandit22@bandit:/usr/bin$ echo I am user bandit23 | md5sum | cut -d ' ' -f 1
8ca319486bfbbc3663ea0fbe81326349

Check the contents of this temporary file.

bandit22@bandit:/usr/bin$ cat /tmp/8ca319486bfbbc3663ea0fbe81326349
jc1udXuA1tiHqjIsL8yaapX5XIAI6i0n

We have obtained the password of bandit23 user.

OvertheWire Bandit Walkthrough: Level 23-24:

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…

Solution:

Check /etc/cron.d directory.

bandit23@bandit:~$ ls /etc/cron.d
atop  cronjob_bandit22  cronjob_bandit23  cronjob_bandit24

Our concern is bandit24 password, therefore check the cronjob_bandit24 cronjob.

bandit23@bandit:~$ cat /etc/cron.d/cronjob_bandit24
@reboot bandit24 /usr/bin/cronjob_bandit24.sh &> /dev/null
* * * * * bandit24 /usr/bin/cronjob_bandit24.sh &> /dev/null

Now, we got the location of the script that is being executed by above cron job.

Check the code of this script.

bandit23@bandit:~$ cat /usr/bin/cronjob_bandit24.sh
#!/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

By analyzing this script, we find out that it is executing all scripts from /var/spool/bandit24 directory.

By listing the permissions of the /var/spool directory, we have observed that we have write permissions on /var/spool/bandit24 directory.

bandit23@bandit:~$ ls -al /var/spool
total 1348
drwxr-xr-x  5 root root        4096 Oct 16  2018 .
drwxr-xr-x 11 root root        4096 Oct 16  2018 ..
drwxrwx-wx 35 root bandit24 1359872 Mar 27 09:04 bandit24
drwxr-xr-x  3 root root        4096 Oct 16  2018 cron
lrwxrwxrwx  1 root root           7 Oct 16  2018 mail -> ../mail
drwx------  2 root root        4096 Jan 14  2018 rsyslog

Let’s create a custom script of our own in this directory. The target is to obtain the password file of bandit24 from /etc/bandit_pass/ to /tmp directory.

bandit23@bandit:~$ nano /var/spool/bandit24/myscript.sh

and following lines of code.

#!/bin/bash
cat /etc/bandit_pass/bandit24 > /tmp/ahmer_bandit24

Make this file executable.

bandit23@bandit:~$ chmod 777 /var/spool/bandit24/myscript.sh

Now wait for a few seconds and then check the file /tmp/ahmer_bandit24.

bandit23@bandit:~$ cat /tmp/ahmer_bandit24
UoMYTrfrBFHyQXmg6gzctqAwOmw1IohZ

We have got the password of bandit24 user.

OvertheWire Bandit Walkthrough: Level 24-25:

Goal:

A daemon is listening on port 30002 and will give you the password for bandit25 if given the password for bandit24 and a secret numeric 4-digit pincode. There is no way to retrieve the pincode except by going through all of the 10000 combinations, called brute-forcing.

Solution:

We have the password of bandit24 user, but the 4 digit pin is unknown. However, we can use brute force technique to generate all possible combinations of 4 digit and then send each of them to the daemon.

The possible number of combinations for n digits is 10ⁿ . Therefore, in present scenario it will be

10⁴ = 10000

We are generating a space separated list of bandit24 password with all the possible combinations of digits between 0000 and 9999 by using the following command.

bandit24@bandit:~$ for i in $(seq -f "%04g" 0 9999); do echo "UoMYTrfrBFHyQXmg6gzctqAwOmw1IohZ" $i >> /tmp/ahmer_pins; done;

Now, we have a text file that contains all the possible combinations. we can submit this file to the daemon running at port 30002 to obtain the password of bandit25 user.

bandit24@bandit:~$ cat /tmp/ahmer_pins | nc localhost 30002 | grep password
I am the pincode checker for user bandit25. Please enter the password for user bandit24 and the secret pincode on a single line, separated by a space.
The password of user bandit25 is uNG9O58gUE7snukf3bvZ0rxhtnjzSGzG

OvertheWire Bandit Walkthrough: Level 25-26:

Goal:

Logging in to bandit26 from bandit25 should be fairly easy… The shell for user bandit26 is not /bin/bash, but something else. Find out what it is, how it works and how to break out of it.

Solution:

We have a private ssh key file located in bandit25 user’s home directory.

bandit25@bandit:~$ ls
bandit26.sshkey

Login as bandit26 user by using this private ssh key file.

bandit25@bandit:~$ ssh bandit26@localhost -i bandit26.sshkey
...
Connection to localhost closed.

When we attempt to login as bandit26 user. The session will end immediately.

Login as bandit25 user and check the default shell of bandit26 user.

bandit25@bandit:~$ grep bandit26 /etc/passwd
bandit26:x:11026:11026:bandit level 26:/home/bandit26:/usr/bin/showtext

Check the contents of the custom shell of bandit26 user.

bandit25@bandit:~$ cat /usr/bin/showtext
#!/bin/sh

export TERM=linux

more ~/text.txt
exit 0

Above script invokes a more command and thereafter exit command that causes the shell to terminate and close the connection.

Actually the size of our PuTTY command window is large enough for the more command to display 100% of the file contents. Therefore, more command executes successfully and then exit command executed and closed the connection.

Reduce the height of the PuTTY window and then try to login again.

The more command is in control now.

Enable vi editor by pressing ‘v’ at the more window.

Now leverage the functionality of the vi editor to invoke a custom shell.

Now execute sh command at vi terminal to spawn a shell.

We are successfully login as the bandit26 user.

OvertheWire Bandit Walkthrough: Level 26-27:

Goal:

Good job getting a shell! Now hurry and grab the password for bandit27!

Solution:

Not much hint given in this challenge. But we have a suid executable in home directory.

bandit26@bandit:~$ ls
bandit27-do  text.txt

Try to execute this file.

bandit26@bandit:~$ ./bandit27-do
Run a command as another user.
  Example: ./bandit27-do id

We know that the passwords are located in /etc/bandit_pass/ directory.

Display the content of bandit27 passwordfile.

bandit26@bandit:~$ ./bandit27-do cat /etc/bandit_pass/bandit27
3ba3118a22e93127a4ed485be72ef5ea

We have got the password of bandit27 user.

OvertheWire Bandit Walkthrough: Level 27-28:

Goal:

There is a git repository at ssh://bandit27-git@localhost/home/bandit27-git/repo. The password for the user bandit27-git is the same as for the user bandit27.

Clone the repository and find the password for the next level.

Solution:

Create a temporary directory to clone the given git repository. (refer to our previous post on git command)

bandit27@bandit:~$ mkdir /tmp/bandit27_ahmer
bandit27@bandit:~$ cd /tmp/bandit27_ahmer

Clone the given git repository as follows.

bandit27@bandit:/tmp/bandit27_ahmer$ git clone ssh://bandit27-git@localhost/home/bandit27-git/repo
Cloning into 'repo'...
Could not create directory '/home/bandit27/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit27/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit27-git@localhost's password:
remote: Counting objects: 3, done.
remote: Compressing objects: 100% (2/2), done.
remote: Total 3 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (3/3), done.

Now check the contents of this git repository.

bandit27@bandit:/tmp/bandit27_ahmer$ cd repo
bandit27@bandit:/tmp/bandit27_ahmer/repo$ ls
README

Display the content of README file.

bandit27@bandit:/tmp/bandit27_ahmer/repo$ cat README
The password to the next level is: 0ef186ac70e04ea33b4c1853d2526fa2

OvertheWire Bandit Walkthrough: Level 28-29:

Goal:

There is a git repository at ssh://bandit28-git@localhost/home/bandit28-git/repo. The password for the user bandit28-git is the same as for the user bandit28.

Clone the repository and find the password for the next level.

Solution:

Create a directory in /tmp directory to clone the git repository.

bandit28@bandit:~$ mkdir /tmp/bandit28_ahmer
bandit28@bandit:~$ cd /tmp/bandit28_ahmer

Clone the given git repository.

bandit28@bandit:/tmp/bandit28_ahmer$ git clone ssh://bandit28-git@localhost/home/bandit28-git/repo
Cloning into 'repo'...
Could not create directory '/home/bandit28/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit28/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit28-git@localhost's password:
remote: Counting objects: 9, done.
remote: Compressing objects: 100% (6/6), done.
remote: Total 9 (delta 2), reused 0 (delta 0)
Receiving objects: 100% (9/9), done.
Resolving deltas: 100% (2/2), done.

Check the contents of this git repository.

bandit28@bandit:/tmp/bandit28_ahmer$ cd repo
bandit28@bandit:/tmp/bandit28_ahmer/repo$ ls
README.md
bandit28@bandit:/tmp/bandit28_ahmer/repo$ cat README.md
# Bandit Notes
Some notes for level29 of bandit.

## credentials

- username: bandit29
- password: xxxxxxxxxx

The password is not available here. But remember that we are working on a version control system. Therefore, check the log of the changes in this repository.

bandit28@bandit:/tmp/bandit28_ahmer/repo$ git log
commit 073c27c130e6ee407e12faad1dd3848a110c4f95
Author: Morla Porla <morla@overthewire.org>
Date:   Tue Oct 16 14:00:39 2018 +0200

    fix info leak

commit 186a1038cc54d1358d42d468cdc8e3cc28a93fcb
Author: Morla Porla <morla@overthewire.org>
Date:   Tue Oct 16 14:00:39 2018 +0200

    add missing data

commit b67405defc6ef44210c53345fc953e6a21338cc7
Author: Ben Dover <noone@overthewire.org>
Date:   Tue Oct 16 14:00:39 2018 +0200

    initial commit of README.md

‘fix info leak’ commit looks suspicious to me. Therefore, we are checking the changes between consecutive commits.

bandit28@bandit:/tmp/bandit28_ahmer/repo$ git diff 073c27c130e6ee407e12faad1dd3848a110c4f95 186a1038cc54d1358d42d468cdc8e3cc28a93fcb
diff --git a/README.md b/README.md
index 5c6457b..3f7cee8 100644
--- a/README.md
+++ b/README.md
@@ -4,5 +4,5 @@ Some notes for level29 of bandit.
 ## credentials

 - username: bandit29
-- password: xxxxxxxxxx
+- password: bbc96594b4e001778eee9975372716b2

We have got the password of the bandit29 user.

OvertheWire Bandit Walkthrough: Level 29-30:

Goal:

There is a git repository at ssh://bandit29-git@localhost/home/bandit29-git/repo. The password for the user bandit29-git is the same as for the user bandit29.

Clone the repository and find the password for the next level.

Solution:

Create a temporary directory to clone given git repository.

bandit29@bandit:~$ mkdir /tmp/bandit29_ahmer
bandit29@bandit:~$ cd /tmp/bandit29_ahmer

Clone the given git repository.

bandit29@bandit:/tmp/bandit29_ahmer$ git clone ssh://bandit29-git@localhost/home/bandit29-git/repo
Cloning into 'repo'...
Could not create directory '/home/bandit29/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit29/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit29-git@localhost's password:
remote: Counting objects: 16, done.
remote: Compressing objects: 100% (11/11), done.
remote: Total 16 (delta 2), reused 0 (delta 0)
Receiving objects: 100% (16/16), done.
Resolving deltas: 100% (2/2), done.

Check the contents of this repository.

bandit29@bandit:/tmp/bandit29_ahmer$ cd repo
bandit29@bandit:/tmp/bandit29_ahmer/repo$ ls
README.md

Print contents of README.md file.

bandit29@bandit:/tmp/bandit29_ahmer/repo$ cat README.md
# Bandit Notes
Some notes for bandit30 of bandit.

## credentials

- username: bandit30
- password: <no passwords in production!>

A clear hint is given in the file that, the password is not available in production branch, therefore, it may be available on dev branch.

List all the branches of this git repository.

bandit29@bandit:/tmp/bandit29_ahmer/repo$ git branch -a
* master
  remotes/origin/HEAD -> origin/master
  remotes/origin/dev
  remotes/origin/master
  remotes/origin/sploits-dev

We have a dev branch available here. Switch to dev branch to see its contents.

bandit29@bandit:/tmp/bandit29_ahmer/repo$ git checkout dev
Branch dev set up to track remote branch dev from origin.
Switched to a new branch 'dev'

Print the contents of README.md file now.

bandit29@bandit:/tmp/bandit29_ahmer/repo$ cat README.md
# Bandit Notes
Some notes for bandit30 of bandit.

## credentials

- username: bandit30
- password: 5b90576bedb2cc04c86a9e924ce42faf

We have found the password of bandit30 user.

OvertheWire Bandit Walkthrough: Level 30-31:

Goal:

There is a git repository at ssh://bandit30-git@localhost/home/bandit30-git/repo. The password for the user bandit30-git is the same as for the user bandit30.

Clone the repository and find the password for the next level.

Solution:

Create a temporary directory to clone the git repository.

bandit30@bandit:~$ mkdir /tmp/bandit31_ahmer
bandit30@bandit:~$ cd /tmp/bandit31_ahmer

Clone git repository as follows.

bandit30@bandit:/tmp/bandit31_ahmer$ git clone ssh://bandit30-git@localhost/home/bandit30-git/repo
Cloning into 'repo'...
Could not create directory '/home/bandit30/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit30/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit30-git@localhost's password:
remote: Counting objects: 4, done.
remote: Total 4 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (4/4), done.

Check the contents of this git repository.

bandit30@bandit:/tmp/bandit31_ahmer$ cd repo
bandit30@bandit:/tmp/bandit31_ahmer/repo$ ls
README.md

Print contents of README.md file.

bandit30@bandit:/tmp/bandit31_ahmer/repo$ cat README.md
just an epmty file... muahaha

This time we got a file without any change log history. Therefore, lets check the other objects related to this repository.

Check if there are any tags in this repository.

bandit30@bandit:/tmp/bandit31_ahmer/repo$ git tag
secret

We have got a suspicious tag here. Check its contents now.

bandit30@bandit:/tmp/bandit31_ahmer/repo$ git show secret
47e603bb428404d265f59c42920d81e5

We have the password of bandit31 user.

OvertheWire Bandit Walkthrough: Level 31-32:

Goal:

There is a git repository at ssh://bandit31-git@localhost/home/bandit31-git/repo. The password for the user bandit31-git is the same as for the user bandit31.

Clone the repository and find the password for the next level.

Solution:

Create a directory in /tmp to clone the given git repository.

bandit31@bandit:~$ mkdir /tmp/bandit32_ahmer
bandit31@bandit:~$ cd /tmp/bandit32_ahmer

Clone the git repository.

bandit31@bandit:/tmp/bandit32_ahmer$ git clone ssh://bandit31-git@localhost/home/bandit31-git/repo
Cloning into 'repo'...
Could not create directory '/home/bandit31/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit31/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit31-git@localhost's password:
remote: Counting objects: 4, done.
remote: Compressing objects: 100% (3/3), done.
remote: Total 4 (delta 0), reused 0 (delta 0)
Receiving objects: 100% (4/4), done.

Check contents of git repository.

bandit31@bandit:/tmp/bandit32_ahmer$ cd repo
bandit31@bandit:/tmp/bandit32_ahmer/repo$ ls
README.md

Print contents of README.md file.

bandit31@bandit:/tmp/bandit32_ahmer/repo$ cat README.md
This time your task is to push a file to the remote repository.

Details:
    File name: key.txt
    Content: 'May I come in?'
    Branch: master

A clear hint is given in this file that, this time we have to create and push a file in git repository.

Create the required file as follows.

bandit31@bandit:/tmp/bandit32_ahmer/repo$ echo "May I come in?" > key.txt

Add key.txt file to git repository.

bandit31@bandit:/tmp/bandit32_ahmer/repo$ git add  key.txt -f

Commit changes to local git repository.

bandit31@bandit:/tmp/bandit32_ahmer/repo$ git commit

Push the changes to the repository origin.

bandit31@bandit:/tmp/bandit32_ahmer/repo$ git push origin
Could not create directory '/home/bandit31/.ssh'.
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:98UL0ZWr85496EtCRkKlo20X3OPnyPSB5tB5RPbhczc.
Are you sure you want to continue connecting (yes/no)? yes
Failed to add the host to the list of known hosts (/home/bandit31/.ssh/known_hosts).
This is a OverTheWire game server. More information on http://www.overthewire.org/wargames

bandit31-git@localhost's password:
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 325 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
remote: ### Attempting to validate files... ####
remote:
remote: .oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.
remote:
remote: Well done! Here is the password for the next level:
remote: 56a9bf19c63d650ce78e6ec0354ee45e
remote:
remote: .oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.oOo.
remote:
To ssh://localhost/home/bandit31-git/repo
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'ssh://bandit31-git@localhost/home/bandit31-git/repo'

We have obtain the password of bandit32 user.

OvertheWire Bandit Walkthrough: Level 32-33:

Goal:

After all this git stuff its time for another escape. Good luck!

Solution:

After login as bandit33, we get the following welcome message.

WELCOME TO THE UPPERCASE SHELL

We have checked that, no command either in lowercase or uppercase are not working in this shell. It looks like that the shell is converting each command to uppercase before executing, therefore, no command is being able to execute.

It means that, this shell is of no use for us. So we try to invoke a regular shell (such as sh or bash).

We can spawn a shell using a shortcut command ‘$0’. This is in fact an environment variable that holds the shell command that is used to execute all the commands in current shell.

Execute ‘$0’ to invoke a regular shell.

>> $0
$

We don’t have any hint to find the bandit33 password. But we know that the passwords are located in /etc/bandit_pass directory.

Display the content of bandit33 passwordfile.

$ cat /etc/bandit_pass/bandit33
c9c3199ddf4121b10cf581a98d51caee

OvertheWire Bandit Walkthrough: Level 33-34:

Goal:

At this moment, level 34 does not exist yet.

Solution:

Check contents of home directory.

bandit33@bandit:~$ ls
README.txt
bandit33@bandit:~$ cat README.txt
Congratulations on solving the last level of this game!

At this moment, there are no more levels to play in this game. However, we are constantly working
on new levels and will most likely expand this game with more levels soon.
Keep an eye out for an announcement on our usual communication channels!
In the meantime, you could play some of our other wargames.

If you have an idea for an awesome new level, please let us know!

Game Over !!

Conclusion – OvertheWire Bandit Walkthrough:

In this article, you have seen complete OvertheWire Bandit Walkthrough.