def build_asreq_lts(self, supported_encryption_method, kdcopts = ['forwardable','renewable','proxiable']):
logger.debug('Constructing TGT request with auth data')
#now to create an AS_REQ with encrypted timestamp for authentication
pa_data_1 = {}
pa_data_1['padata-type'] = int(PADATA_TYPE('PA-PAC-REQUEST'))
pa_data_1['padata-value'] = PA_PAC_REQUEST({'include-pac': True}).dump()
now = datetime.datetime.now(datetime.timezone.utc)
#creating timestamp asn1
timestamp = PA_ENC_TS_ENC({'patimestamp': now.replace(microsecond=0), 'pausec': now.microsecond}).dump()
logger.debug('Selecting common encryption type: %s' % supported_encryption_method.name)
self.kerberos_cipher = _enctype_table[supported_encryption_method.value]
self.kerberos_cipher_type = supported_encryption_method.value
self.kerberos_key = Key(self.kerberos_cipher.enctype, self.usercreds.get_key_for_enctype(supported_encryption_method, salt = self.server_salt))
enc_timestamp = self.kerberos_cipher.encrypt(self.kerberos_key, 1, timestamp, None)
pa_data_2 = {}
pa_data_2['padata-type'] = int(PADATA_TYPE('ENC-TIMESTAMP'))
pa_data_2['padata-value'] = EncryptedData({'etype': supported_encryption_method.value, 'cipher': enc_timestamp}).dump()
kdc_req_body = {}
kdc_req_body['kdc-options'] = KDCOptions(set(kdcopts))
kdc_req_body['cname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': [self.usercreds.username]})
kdc_req_body['realm'] = self.usercreds.domain.upper()
kdc_req_body['sname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': ['krbtgt', self.usercreds.domain.upper()]})
kdc_req_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['rtime'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['nonce'] = secrets.randbits(31)
kdc_req_body['etype'] = [supported_encryption_method.value] #selecting according to server's preferences
kdc_req = {}
kdc_req['pvno'] = krb5_pvno
kdc_req['msg-type'] = MESSAGE_TYPE.KRB_AS_REQ.value
kdc_req['padata'] = [pa_data_2,pa_data_1]
kdc_req['req-body'] = KDC_REQ_BODY(kdc_req_body)
return AS_REQ(kdc_req)
def construct_tgt_req(self):
now = now = datetime.datetime.now(datetime.timezone.utc)
kdc_req_body = {}
kdc_req_body['kdc-options'] = KDCOptions(
set(['forwardable', 'renewable', 'proxiable']))
kdc_req_body['cname'] = PrincipalName({
'name-type':
NAME_TYPE.PRINCIPAL.value,
'name-string': [self.spn.username]
})
kdc_req_body['realm'] = self.spn.domain.upper()
kdc_req_body['sname'] = PrincipalName({
'name-type':
NAME_TYPE.PRINCIPAL.value,
'name-string': ['krbtgt', self.spn.domain.upper()]
})
kdc_req_body['till'] = (now + datetime.timedelta(days=1)).replace(
microsecond=0)
kdc_req_body['rtime'] = (now + datetime.timedelta(days=1)).replace(
microsecond=0)
kdc_req_body['nonce'] = secrets.randbits(31)
kdc_req_body['etype'] = [2, 3, 16, 23, 17,
18] #we "support" all MS related enctypes
pa_data_1 = {}
pa_data_1['padata-type'] = int(PADATA_TYPE('PA-PAC-REQUEST'))
pa_data_1['padata-value'] = PA_PAC_REQUEST({
'include-pac': True
}).dump()
kdc_req = {}
kdc_req['pvno'] = krb5_pvno
kdc_req['msg-type'] = MESSAGE_TYPE.KRB_AS_REQ.value
kdc_req['padata'] = [pa_data_1]
kdc_req['req-body'] = KDC_REQ_BODY(kdc_req_body)
return AS_REQ(kdc_req)
def do_preauth(self, rep):
#now getting server's supported encryption methods
supp_enc_methods = collections.OrderedDict()
for enc_method in METHOD_DATA.load(rep['e-data']).native:
data_type = PaDataType(enc_method['padata-type'])
if data_type == PaDataType.ETYPE_INFO or data_type == PaDataType.ETYPE_INFO2:
if data_type == PaDataType.ETYPE_INFO:
enc_info_list = ETYPE_INFO.load(enc_method['padata-value'])
elif data_type == PaDataType.ETYPE_INFO2:
enc_info_list = ETYPE_INFO2.load(enc_method['padata-value'])
for enc_info in enc_info_list.native:
supp_enc_methods[EncryptionType(enc_info['etype'])] = enc_info['salt']
logger.debug('Server supports encryption type %s with salt %s' % (EncryptionType(enc_info['etype']).name, enc_info['salt']))
logger.debug('Constructing TGT request with auth data')
#now to create an AS_REQ with encrypted timestamp for authentication
pa_data_1 = {}
pa_data_1['padata-type'] = int(PADATA_TYPE('PA-PAC-REQUEST'))
pa_data_1['padata-value'] = PA_PAC_REQUEST({'include-pac': True}).dump()
now = datetime.datetime.now(datetime.timezone.utc)
#creating timestamp asn1
timestamp = PA_ENC_TS_ENC({'patimestamp': now.replace(microsecond=0), 'pausec': now.microsecond}).dump()
supp_enc = self.usercreds.get_preferred_enctype(supp_enc_methods)
logger.debug('Selecting common encryption type: %s' % supp_enc.name)
self.kerberos_cipher = _enctype_table[supp_enc.value]
self.kerberos_cipher_type = supp_enc.value
if 'salt' in enc_info and enc_info['salt'] is not None:
self.server_salt = enc_info['salt'].encode()
self.kerberos_key = Key(self.kerberos_cipher.enctype, self.usercreds.get_key_for_enctype(supp_enc, salt = self.server_salt))
enc_timestamp = self.kerberos_cipher.encrypt(self.kerberos_key, 1, timestamp, None)
pa_data_2 = {}
pa_data_2['padata-type'] = int(PADATA_TYPE('ENC-TIMESTAMP'))
pa_data_2['padata-value'] = EncryptedData({'etype': supp_enc.value, 'cipher': enc_timestamp}).dump()
kdc_req_body = {}
kdc_req_body['kdc-options'] = KDCOptions(set(['forwardable','renewable','proxiable']))
kdc_req_body['cname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': [self.usercreds.username]})
kdc_req_body['realm'] = self.usercreds.domain.upper()
kdc_req_body['sname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': ['krbtgt', self.usercreds.domain.upper()]})
kdc_req_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['rtime'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['nonce'] = secrets.randbits(31)
kdc_req_body['etype'] = [supp_enc.value]
kdc_req = {}
kdc_req['pvno'] = krb5_pvno
kdc_req['msg-type'] = MESSAGE_TYPE.KRB_AS_REQ.value
kdc_req['padata'] = [pa_data_2,pa_data_1]
kdc_req['req-body'] = KDC_REQ_BODY(kdc_req_body)
req = AS_REQ(kdc_req)
logger.debug('Sending TGT request to server')
return self.ksoc.sendrecv(req.dump())
def get_TGT(self, override_etype = None, decrypt_tgt = True):
"""
decrypt_tgt: used for asreproast attacks
Steps performed:
1. Send and empty (no encrypted timestamp) AS_REQ with all the encryption types we support
2. Depending on the response (either error or AS_REP with TGT) we either send another AS_REQ with the encrypted data or return the TGT (or fail miserably)
3. PROFIT
"""
logger.debug('[getTGT] Generating initial TGT without authentication data')
now = datetime.datetime.now(datetime.timezone.utc)
kdc_req_body = {}
kdc_req_body['kdc-options'] = KDCOptions(set(['forwardable','renewable','proxiable']))
kdc_req_body['cname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': [self.usercreds.username]})
kdc_req_body['realm'] = self.usercreds.domain.upper()
kdc_req_body['sname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': ['krbtgt', self.usercreds.domain.upper()]})
kdc_req_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['rtime'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['nonce'] = secrets.randbits(31)
if override_etype is None:
kdc_req_body['etype'] = self.usercreds.get_supported_enctypes()
else:
kdc_req_body['etype'] = override_etype
pa_data_1 = {}
pa_data_1['padata-type'] = int(PADATA_TYPE('PA-PAC-REQUEST'))
pa_data_1['padata-value'] = PA_PAC_REQUEST({'include-pac': True}).dump()
kdc_req = {}
kdc_req['pvno'] = krb5_pvno
kdc_req['msg-type'] = MESSAGE_TYPE.KRB_AS_REQ.value
kdc_req['padata'] = [pa_data_1]
kdc_req['req-body'] = KDC_REQ_BODY(kdc_req_body)
req = AS_REQ(kdc_req)
logger.debug('[getTGT] Sending initial TGT to %s' % self.ksoc.get_addr_str())
rep = self.ksoc.sendrecv(req.dump(), throw = False)
if rep.name != 'KRB_ERROR':
#user can do kerberos auth without preauthentication!
self.kerberos_TGT = rep.native
etype = self.kerberos_TGT['enc-part']['etype']
#if we want to roast the asrep (tgt rep) part then we dont even have the proper keys to decrypt
#so we just return, the asrep can be extracted from this object anyhow
if decrypt_tgt == False:
return
self.kerberos_cipher = _enctype_table[etype]
self.kerberos_cipher_type = etype
encryption_type = EncryptionType(self.kerberos_cipher.enctype)
enctype = self.usercreds.get_key_for_enctype(encryption_type)
self.kerberos_key = Key(self.kerberos_cipher.enctype, enctype)
else:
if rep.native['error-code'] != KerberosErrorCode.KDC_ERR_PREAUTH_REQUIRED.value:
raise KerberosError(rep)
rep = rep.native
logger.debug('[getTGT] Got reply from server, asking to provide auth data')
rep = self.do_preauth(rep)
logger.debug('[getTGT] Got valid response from server')
rep = rep.native
self.kerberos_TGT = rep
cipherText = self.kerberos_TGT['enc-part']['cipher']
temp = self.kerberos_cipher.decrypt(self.kerberos_key, 3, cipherText)
try:
self.kerberos_TGT_encpart = EncASRepPart.load(temp).native
except Exception as e:
logger.debug('[getTGT] EncAsRepPart load failed, is this linux?')
try:
self.kerberos_TGT_encpart = EncTGSRepPart.load(temp).native
except Exception as e:
logger.error('[getTGT] Failed to load decrypted part of the reply!')
raise e
self.kerberos_session_key = Key(self.kerberos_cipher.enctype, self.kerberos_TGT_encpart['key']['keyvalue'])
self.ccache.add_tgt(self.kerberos_TGT, self.kerberos_TGT_encpart, override_pp = True)
logger.debug('[getTGT] Got valid TGT')
return
def build_asreq_pkinit(
self,
supported_encryption_method,
kdcopts=['forwardable', 'renewable', 'renewable-ok']):
from asn1crypto import keys
if supported_encryption_method.value == 23:
raise Exception(
'RC4 encryption is not supported for certificate auth!')
now = datetime.datetime.now(datetime.timezone.utc)
kdc_req_body_data = {}
kdc_req_body_data['kdc-options'] = KDCOptions(set(kdcopts))
kdc_req_body_data['cname'] = PrincipalName({
'name-type':
NAME_TYPE.PRINCIPAL.value,
'name-string': [self.usercreds.username]
})
kdc_req_body_data['realm'] = self.usercreds.domain.upper()
kdc_req_body_data['sname'] = PrincipalName({
'name-type':
NAME_TYPE.SRV_INST.value,
'name-string': ['krbtgt', self.usercreds.domain.upper()]
})
kdc_req_body_data['till'] = (now + datetime.timedelta(days=1)).replace(
microsecond=0)
kdc_req_body_data['rtime'] = (now +
datetime.timedelta(days=1)).replace(
microsecond=0)
kdc_req_body_data['nonce'] = secrets.randbits(31)
kdc_req_body_data['etype'] = [supported_encryption_method.value
] #[18,17] # 23 breaks...
kdc_req_body = KDC_REQ_BODY(kdc_req_body_data)
checksum = hashlib.sha1(kdc_req_body.dump()).digest()
authenticator = {}
authenticator['cusec'] = now.microsecond
authenticator['ctime'] = now.replace(microsecond=0)
authenticator['nonce'] = secrets.randbits(31)
authenticator['paChecksum'] = checksum
dp = {}
dp['p'] = self.usercreds.dhparams.p
dp['g'] = self.usercreds.dhparams.g
dp['q'] = 0 # mandatory parameter, but it is not needed
pka = {}
pka['algorithm'] = '1.2.840.10046.2.1'
pka['parameters'] = keys.DomainParameters(dp)
spki = {}
spki['algorithm'] = keys.PublicKeyAlgorithm(pka)
spki['public_key'] = self.usercreds.dhparams.get_public_key()
authpack = {}
authpack['pkAuthenticator'] = PKAuthenticator(authenticator)
authpack['clientPublicValue'] = keys.PublicKeyInfo(spki)
authpack['clientDHNonce'] = self.usercreds.dhparams.dh_nonce
authpack = AuthPack(authpack)
signed_authpack = self.usercreds.sign_authpack(authpack.dump(),
wrap_signed=True)
payload = PA_PK_AS_REQ()
payload['signedAuthPack'] = signed_authpack
pa_data_1 = {}
pa_data_1['padata-type'] = PaDataType.PK_AS_REQ.value
pa_data_1['padata-value'] = payload.dump()
pa_data_0 = {}
pa_data_0['padata-type'] = int(PADATA_TYPE('PA-PAC-REQUEST'))
pa_data_0['padata-value'] = PA_PAC_REQUEST({
'include-pac': True
}).dump()
asreq = {}
asreq['pvno'] = 5
asreq['msg-type'] = 10
asreq['padata'] = [pa_data_0, pa_data_1]
asreq['req-body'] = kdc_req_body
return AS_REQ(asreq)