Level 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.

In this level, we need to connect using the ssh -t. The -t parameter basically opens a pseudo-tty within the session, with output in the same screen. The ssh session closes when the command completes. This way, you can quickly run a command before the connectivity closes and kicks you out with a “Byebye!”.

bandit17@melinda:~$ ssh -t bandit18@localhost cat readme
 The authenticity of host 'localhost (127.0.0.1)' can't be established.
 ECDSA key fingerprint is 05:3a:1c:25:35:0a:ed:2f:cd:87:1c:f6:fe:69:e4:f6.
 {... REMOVED ...}
 Permissions 0640 for '/home/bandit17/.ssh/id_rsa' are too open.
 It is required that your private key files are NOT accessible by others.
 This private key will be ignored.
 bad permissions: ignore key: /home/bandit17/.ssh/id_rsa
 bandit18@localhost's password:
 readme
 Connection to localhost closed.

Next, we run the same commands to check what is in the “readme” file.

bandit18@localhost's password:
IueksS7Ubh8G3DCwVzrTd8rAVOwq3M5x
Connection to localhost closed.

The password to gain access to the next level is IueksS7Ubh8G3DCwVzrTd8rAVOwq3M5x.

Level goal: There are 2 files in the homedirectory: passwords.old and passwords.new. The password for the next level is in passwords.newand 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.

Here you see 2 password files. As the hint goes, New vs Old, the first thing to come to mind is to perform the diff function.

bandit17@melinda:~$ diff passwords.new passwords.old
42c42
< kfBf3eYk5BPBRzwjqutbbfE887SVc5Yd
---
> BS8bqB1kqkinKJjuxL6k072Qq9NRwQpR

The password is kfBf3eYk5BPBRzwjqutbbfE887SVc5Yd. To verify whether this is the correct password, we will follow the hint, which is to try to connect to bandit18 and see if we see the “Byebye!” message.

The password to gain access to the next level is kfBf3eYk5BPBRzwjqutbbfE887SVc5Yd.

Level 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

This level require us to have basic understanding in port scanning and identifying the services. First, let’s perform a port scan to identify the open ports between the range of 31000 to 32000.

bandit16@melinda:~$ nmap localhost -p31000-32000

Starting Nmap 6.40 ( http://nmap.org ) at 2016-09-10 14:17 UTC
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00088s latency).
Not shown: 996 closed ports
PORT STATE SERVICE
31046/tcp open unknown
31518/tcp open unknown
31691/tcp open unknown
31790/tcp open unknown
31960/tcp open unknown

Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds

Now there we have shortlisted only 5 ports with services, we will test if it is configured to accept normal connectivity or restricted to only SSL connectivity. For instance, we can do it using the following command,

bandit16@melinda:~$ echo test | nc -v localhost 31046
Connection to localhost 31046 port [tcp/*] succeeded!
test

We see that port 31046 is able to accept non-SSL connection, which means that this is not our target. Let’s check out the other 4 ports as well.

Now, we will focus on the 2 ports which produced error output because they are configured to restrict connectivity to SSL only. We will now try to connect using openssl with s_client option, to check if there is any correct output.

bandit16@melinda:~$ echo cluFn7wTiGryunymYOu4RcffSxQluehd | openssl s_client -quiet -connect localhost:31790
depth=0 CN = li190-250.members.linode.com
verify error:num=18:self signed certificate
verify return:1
depth=0 CN = li190-250.members.linode.com
verify return:1
Correct!
{ ... RSA PRIVATE KEY ... }

The private key for accessing the next level is stored in port 31790! Now, I have to save this RSA private key into a file and then use it to connect to the next level.

After you’re done with the “copy and paste”, try to connect, you should encounter an error message, which is a good learning point with regards to RSA keys permissions,

The fix is very simple, simply modify the file permission and set it as 400 and you are good to go!

There you go, you are in!

Level 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…

In this level, we connect to the port 30001 on localhost using the SSL encryption. We can do it using the openssl command.

bandit15@melinda:~$ openssl s_client -quiet -connect 127.0.0.1:30001
depth=0 CN = li190-250.members.linode.com
verify error:num=18:self signed certificate
verify return:1
depth=0 CN = li190-250.members.linode.com
verify return:1
BfMYroe26WYalil77FoDi9qh59eK5xNr
Correct!
cluFn7wTiGryunymYOu4RcffSxQluehd

read:errno=0

The password to gain access to the next level is cluFn7wTiGryunymYOu4RcffSxQluehd.

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

Surprisingly, I have already accidentally resolved this level from my previous level’s writeup.

As mentioned in the level 0 introduction page, all level’s passwords are stored in /etc/bandit_pass/ but they can only be accessed by the level’s user themselves.

Now that we are logged in to bandit14, we can retrieve its password, which is 4wcYUJFw0k0XLShlDzztnTBHiqxU3b3e.

Now, we need to submit it to port 30000 on localhost. We can do it using many ways, one of them is netcat.

bandit14@melinda:~$ nc localhost 30000
4wcYUJFw0k0XLShlDzztnTBHiqxU3b3e
Correct!
BfMYroe26WYalil77FoDi9qh59eK5xNr

Another way is using telnet, well, either way works. There are many other ways too, let’s not get into that.

bandit14@melinda:~$ telnet localhost 30000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
4wcYUJFw0k0XLShlDzztnTBHiqxU3b3e
Correct!
BfMYroe26WYalil77FoDi9qh59eK5xNr

Connection closed by foreign host.

The password to gain access to the next level is BfMYroe26WYalil77FoDi9qh59eK5xNr.