OverTheWire Wargames

Bandit Level 16 –> Level 17

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.

Commands you may need to solve this level

ssh, telnet, nc, openssl, s_client, nmap

Solution

Check which ports have a server listening, on interval (31000-32000)

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

Starting Nmap 7.40 ( https://nmap.org ) at 2021-03-23 10:59 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00029s 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: 1IP address (1 host up) scanned in 0.09 seconds

check SSL connection for each port (one which speak ssl will not reply)

bandit16@bandit:~$ echo test | nc -v localhost 31046
localhost [127.0.0.1] 31046 (?) open
test

bandit16@bandit:~$ echo test | nc -v localhost 31518
localhost [127.0.0.1] 31518 (?) open

bandit16@bandit:~$ echo test | nc -v localhost 31691
localhost [127.0.0.1] 31691 (?) open
test

bandit16@bandit:~$ echo test | nc -v localhost 31790
localhost [127.0.0.1] 31790 (?) open

bandit16@bandit:~$ echo test | nc -v localhost 31960
localhost [127.0.0.1] 31960 (?) open
test

So port 31790, 31518 speak ssl let’s try this time with pass

bandit16@bandit:~$ echo cluFn7wTiGryunymYOu4RcffSxQluehd | openssl s_client -quiet -connect localhost:31518
depth=0 CN = localhost
verify error:num=18:self signed certificate
verify return:1
depth=0 CN = localhost
verify return:1
cluFn7wTiGryunymYOu4RcffSxQluehd

*(it reply with same password so it isn’t ours

bandit16@bandit:~$ echo cluFn7wTiGryunymYOu4RcffSxQluehd | openssl s_client -quiet -connect localhost:31790
depth=0 CN = localhost
verify error:num=18:self signed certificate
verify return:1
depth=0 CN = localhost
verify return:1
Correct!
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

As we made in previous level we can login next level by private key, so copy it in new file you can made in tmp directory

bandit16@bandit:~$ nano /tmp/private_key16
bandit16@bandit:~$ ssh -i /tmp/private_key16 bandit17@localhost

We can’t enter as this massege show “Permissions 0644 for ‘/tmp/private_key16’ are too open. It is required that your private key files are NOT accessible by others.” to privent that change mode of private key file so no one have the permission to open it except us.

chmod 600 /tmp/private_key16

Now connect will success

ssh -i /tmp/private_key16 bandit17@localhost

Password

xLYVMN9WE5zQ5vHacb0sZEVqbrp7nBTn

ctf-writeups