def construct_apreq(self, tgs, encTGSRepPart, sessionkey, flags = None, seq_number = 0, ap_opts = []):
now = datetime.datetime.now(datetime.timezone.utc)
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(self.kerberos_TGT['crealm'])
authenticator_data['cname'] = self.kerberos_TGT['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
if flags is not None:
ac = AuthenticatorChecksum()
ac.flags = flags
ac.channel_binding = b'\x00'*16
chksum = {}
chksum['cksumtype'] = 0x8003
chksum['checksum'] = ac.to_bytes()
authenticator_data['cksum'] = Checksum(chksum)
authenticator_data['seq-number'] = seq_number
cipher = _enctype_table[encTGSRepPart['key']['keytype']]
authenticator_data_enc = cipher.encrypt(sessionkey, 11, Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ticket'] = Ticket(tgs['ticket'])
ap_req['ap-options'] = APOptions(set(ap_opts))
ap_req['authenticator'] = EncryptedData({'etype': self.kerberos_cipher_type, 'cipher': authenticator_data_enc})
return AP_REQ(ap_req).dump()
def construct_apreq_from_ticket(ticket_data, sessionkey, crealm, cname, flags = None, seq_number = 0, ap_opts = []):
"""
ticket: bytes of Ticket
"""
now = datetime.datetime.now(datetime.timezone.utc)
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(crealm)
authenticator_data['cname'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': [cname]})
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
if flags is not None:
ac = AuthenticatorChecksum()
ac.flags = flags
ac.channel_binding = b'\x00'*16
chksum = {}
chksum['cksumtype'] = 0x8003
chksum['checksum'] = ac.to_bytes()
authenticator_data['cksum'] = Checksum(chksum)
authenticator_data['seq-number'] = seq_number
cipher = _enctype_table[sessionkey.enctype]
authenticator_data_enc = cipher.encrypt(sessionkey, 11, Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ticket'] = Ticket.load(ticket_data)
ap_req['ap-options'] = APOptions(set(ap_opts))
ap_req['authenticator'] = EncryptedData({'etype': sessionkey.enctype, 'cipher': authenticator_data_enc})
return AP_REQ(ap_req).dump()
def add_tgs(self, tgs_rep, enc_tgs_rep_part, override_pp = False): #from AS_REP """ Creates credential object from the TGS and adds to the ccache file The TGS is the native representation of the asn1 encoded TGS_REP data when the user requests a tgs to a specific service principal with a valid TGT This function doesn't do decryption of the encrypted part of the tgs_rep object, it is expected that the decrypted XXX is supplied in enc_as_rep_part override_pp: bool to determine if client principal should be used as the primary principal for the ccache file """ c = Credential() c.client = CCACHEPrincipal.from_asn1(tgs_rep['cname'], tgs_rep['crealm']) if override_pp == True: self.primary_principal = c.client c.server = CCACHEPrincipal.from_asn1(enc_tgs_rep_part['sname'], enc_tgs_rep_part['srealm']) c.time = Times.from_asn1(enc_tgs_rep_part) c.key = Keyblock.from_asn1(enc_tgs_rep_part['key']) c.is_skey = 0 #not sure! c.tktflags = TicketFlags(enc_tgs_rep_part['flags']).cast(core.IntegerBitString).native c.num_address = 0 c.num_authdata = 0 c.ticket = CCACHEOctetString.from_asn1(Ticket(tgs_rep['ticket']).dump()) c.second_ticket = CCACHEOctetString.empty() self.credentials.append(c)
def to_kirbi(self):
filename = '%s@%s_%s' % (self.client.to_string() , self.server.to_string(), hashlib.sha1(self.ticket.to_asn1()).hexdigest()[:8])
krbcredinfo = {}
krbcredinfo['key'] = EncryptionKey(self.key.to_asn1())
krbcredinfo['prealm'] = self.client.realm.to_string()
krbcredinfo['pname'] = self.client.to_asn1()[0]
krbcredinfo['flags'] = core.IntegerBitString(self.tktflags).cast(TicketFlags)
if self.time.authtime != 0: #this parameter is not mandatory, and most of the time not present
krbcredinfo['authtime'] = datetime.datetime.fromtimestamp(self.time.authtime)
krbcredinfo['starttime'] = datetime.datetime.fromtimestamp(self.time.starttime)
krbcredinfo['endtime'] = datetime.datetime.fromtimestamp(self.time.endtime)
if self.time.renew_till != 0: #this parameter is not mandatory, and sometimes it's not present
krbcredinfo['renew-till'] = datetime.datetime.fromtimestamp(self.time.authtime)
krbcredinfo['srealm'] = self.server.realm.to_string()
krbcredinfo['sname'] = self.server.to_asn1()[0]
enc_krbcred = {}
enc_krbcred['ticket-info'] = [KrbCredInfo(krbcredinfo)]
krbcred = {}
krbcred['pvno'] = krb5_pvno
krbcred['msg-type'] = MESSAGE_TYPE.KRB_CRED.value
krbcred['tickets'] = [Ticket.load(self.ticket.to_asn1())]
krbcred['enc-part'] = EncryptedData({'etype': EncryptionType.NULL.value, 'cipher': EncKrbCredPart(enc_krbcred).dump()})
kirbi = KRBCRED(krbcred)
return kirbi, filename
def get_hashes(self, all_hashes = False): """ Returns a list of hashes in hashcat-firendly format for tickets with encryption type 23 (which is RC4) all_hashes: overrides the encryption type filtering and returns hash for all tickets """ hashes = [] for cred in self.credentials: res = Ticket.load(cred.ticket.to_asn1()).native if int(res['enc-part']['etype']) == 23 or all_hashes == True: hashes.append(cred.to_hash()) return hashes
def to_asn1(self):
krbcredinfo = {}
krbcredinfo['key'] = EncryptionKey({
'keytype': self.KeyType,
'keyvalue': self.Key
})
krbcredinfo['prealm'] = self.AltTargetDomainName
krbcredinfo['pname'] = PrincipalName({
'name-type': self.EClientName_type,
'name-string': self.EClientName
})
krbcredinfo['flags'] = core.IntegerBitString(
self.TicketFlags).cast(TicketFlags)
krbcredinfo['starttime'] = self.StartTime
krbcredinfo['endtime'] = self.EndTime
krbcredinfo['renew-till'] = self.RenewUntil
krbcredinfo['srealm'] = self.DomainName
krbcredinfo['sname'] = PrincipalName({
'name-type': self.ServiceName_type,
'name-string': self.ServiceName
})
enc_krbcred = {}
enc_krbcred['ticket-info'] = [KrbCredInfo(krbcredinfo)]
ticket = {}
ticket['tkt-vno'] = krb5_pvno
ticket['realm'] = self.DomainName
ticket['sname'] = PrincipalName({
'name-type': NAME_TYPE.SRV_INST.value,
'name-string': self.ServiceName
})
ticket['enc-part'] = EncryptedData({
'etype': self.TicketEncType,
'kvno': self.TicketKvno,
'cipher': self.Ticket
})
krbcred = {}
krbcred['pvno'] = krb5_pvno
krbcred['msg-type'] = MESSAGE_TYPE.KRB_CRED.value
krbcred['tickets'] = [Ticket(ticket)]
krbcred['enc-part'] = EncryptedData({
'etype':
EncryptionType.NULL.value,
'cipher':
EncKrbCredPart(enc_krbcred).dump()
})
return KRBCRED(krbcred)
def to_hash(self): res = Ticket.load(self.ticket.to_asn1()).native tgs_encryption_type = int(res['enc-part']['etype']) t = len(res['sname']['name-string']) if t == 1: tgs_name_string = res['sname']['name-string'][0] else: tgs_name_string = res['sname']['name-string'][1] tgs_realm = res['realm'] if tgs_encryption_type == EncryptionType.AES256_CTS_HMAC_SHA1_96.value: tgs_checksum = res['enc-part']['cipher'][-12:] tgs_encrypted_data2 = res['enc-part']['cipher'][:-12:] return '$krb5tgs$%s$%s$%s$%s$%s' % (tgs_encryption_type,tgs_name_string,tgs_realm, tgs_checksum.hex(), tgs_encrypted_data2.hex() ) else: tgs_checksum = res['enc-part']['cipher'][:16] tgs_encrypted_data2 = res['enc-part']['cipher'][16:] return '$krb5tgs$%s$*%s$%s$spn*$%s$%s' % (tgs_encryption_type,tgs_name_string,tgs_realm, tgs_checksum.hex(), tgs_encrypted_data2.hex() )
def to_tgt(self):
"""
Returns the native format of an AS_REP message and the sessionkey in EncryptionKey native format
"""
enc_part = EncryptedData({'etype': 1, 'cipher': b''})
tgt_rep = {}
tgt_rep['pvno'] = krb5_pvno
tgt_rep['msg-type'] = MESSAGE_TYPE.KRB_AS_REP.value
tgt_rep['crealm'] = self.server.realm.to_string()
tgt_rep['cname'] = self.client.to_asn1()[0]
tgt_rep['ticket'] = Ticket.load(self.ticket.to_asn1()).native
tgt_rep['enc-part'] = enc_part.native
t = EncryptionKey(self.key.to_asn1()).native
return tgt_rep, t
def add_kirbi(self, krbcred, override_pp=True, include_expired=False):
c = Credential()
enc_credinfo = EncKrbCredPart.load(
krbcred['enc-part']['cipher']).native
ticket_info = enc_credinfo['ticket-info'][0]
"""
if ticket_info['endtime'] < datetime.datetime.now(datetime.timezone.utc):
if include_expired == True:
logging.debug('This ticket has most likely expired, but include_expired is forcing me to add it to cache! This can cause problems!')
else:
logging.debug('This ticket has most likely expired, skipping')
return
"""
c.client = CCACHEPrincipal.from_asn1(ticket_info['pname'],
ticket_info['prealm'])
if override_pp == True:
self.primary_principal = c.client
#yaaaaay 4 additional weirdness!!!!
#if sname name-string contains a realm as well htne impacket will crash miserably :(
if len(ticket_info['sname']['name-string']
) > 2 and ticket_info['sname']['name-string'][-1].upper(
) == ticket_info['srealm'].upper():
logger.debug('SNAME contains the realm as well, trimming it')
t = ticket_info['sname']
t['name-string'] = t['name-string'][:-1]
c.server = CCACHEPrincipal.from_asn1(t, ticket_info['srealm'])
else:
c.server = CCACHEPrincipal.from_asn1(ticket_info['sname'],
ticket_info['srealm'])
c.time = Times.from_asn1(ticket_info)
c.key = Keyblock.from_asn1(ticket_info['key'])
c.is_skey = 0 #not sure!
c.tktflags = TicketFlags(ticket_info['flags']).cast(
core.IntegerBitString).native
c.num_address = 0
c.num_authdata = 0
c.ticket = CCACHEOctetString.from_asn1(
Ticket(krbcred['tickets']
[0]).dump()) #kirbi only stores one ticket per file
c.second_ticket = CCACHEOctetString.empty()
self.credentials.append(c)
async def authenticate(self,
authData,
flags=None,
seq_number=0,
is_rpc=False):
try:
if self.kc is None:
_, err = await self.setup_kc()
if err is not None:
return None, None, err
if self.iterations == 0:
try:
#check TGS first, maybe ccache already has what we need
for target in self.ccred.ccache.list_targets():
# just printing this to debug...
logger.debug('CCACHE target SPN record: %s' % target)
tgs, encpart, self.session_key = await self.kc.get_TGS(
self.spn)
self.from_ccache = True
except Exception as e:
# this is normal when no credentials stored in ccache
#tgt = await self.kc.get_TGT(override_etype=[18])
tgt = await self.kc.get_TGT()
tgs, encpart, self.session_key = await self.kc.get_TGS(
self.spn)
ap_opts = []
if is_rpc == True:
if self.iterations == 0:
ap_opts.append('mutual-required')
flags = ChecksumFlags.GSS_C_CONF_FLAG | ChecksumFlags.GSS_C_INTEG_FLAG | ChecksumFlags.GSS_C_SEQUENCE_FLAG|\
ChecksumFlags.GSS_C_REPLAY_FLAG | ChecksumFlags.GSS_C_MUTUAL_FLAG | ChecksumFlags.GSS_C_DCE_STYLE
if self.from_ccache is False:
apreq = self.kc.construct_apreq(tgs,
encpart,
self.session_key,
flags=flags,
seq_number=seq_number,
ap_opts=ap_opts)
else:
apreq = self.kc.construct_apreq_from_ticket(
Ticket(tgs['ticket']).dump(),
self.session_key,
tgs['crealm'],
tgs['cname']['name-string'][0],
flags=flags,
seq_number=seq_number,
ap_opts=ap_opts,
cb_data=None)
self.iterations += 1
return apreq, False, None
else:
#mutual authentication part here
self.seq_number = seq_number
aprep = AP_REP.load(authData).native
cipher = _enctype_table[int(aprep['enc-part']['etype'])]()
cipher_text = aprep['enc-part']['cipher']
temp = cipher.decrypt(self.session_key, 12, cipher_text)
enc_part = EncAPRepPart.load(temp).native
cipher = _enctype_table[int(
enc_part['subkey']['keytype'])]()
now = datetime.datetime.now(datetime.timezone.utc)
apreppart_data = {}
apreppart_data['cusec'] = now.microsecond
apreppart_data['ctime'] = now.replace(microsecond=0)
apreppart_data['seq-number'] = enc_part['seq-number']
#print('seq %s' % enc_part['seq-number'])
apreppart_data_enc = cipher.encrypt(
self.session_key, 12,
EncAPRepPart(apreppart_data).dump(), None)
#overriding current session key
self.session_key = Key(cipher.enctype,
enc_part['subkey']['keyvalue'])
ap_rep = {}
ap_rep['pvno'] = 5
ap_rep['msg-type'] = MESSAGE_TYPE.KRB_AP_REP.value
ap_rep['enc-part'] = EncryptedData({
'etype':
self.session_key.enctype,
'cipher':
apreppart_data_enc
})
token = AP_REP(ap_rep).dump()
self.gssapi = get_gssapi(self.session_key)
self.iterations += 1
return token, False, None
else:
if self.from_ccache is False:
apreq = self.kc.construct_apreq(tgs,
encpart,
self.session_key,
flags=flags,
seq_number=seq_number,
ap_opts=ap_opts)
else:
apreq = self.kc.construct_apreq_from_ticket(
Ticket(tgs['ticket']).dump(),
self.session_key,
tgs['crealm'],
tgs['cname']['name-string'][0],
flags=flags,
seq_number=seq_number,
ap_opts=ap_opts,
cb_data=None)
return apreq, False, None
except Exception as e:
return None, None, e
def S4U2proxy(self, s4uself_ticket, spn_user, supp_enc_methods = [EncryptionType.DES_CBC_CRC,EncryptionType.DES_CBC_MD4,EncryptionType.DES_CBC_MD5,EncryptionType.DES3_CBC_SHA1,EncryptionType.ARCFOUR_HMAC_MD5,EncryptionType.AES256_CTS_HMAC_SHA1_96,EncryptionType.AES128_CTS_HMAC_SHA1_96]):
logger.debug('[S4U2proxy] Impersonating %s' % '/'.join(spn_user.get_principalname()))
now = datetime.datetime.now(datetime.timezone.utc)
supp_enc = self.usercreds.get_preferred_enctype(supp_enc_methods)
pa_pac_opts = {}
pa_pac_opts['padata-type'] = int(PADATA_TYPE('PA-PAC-OPTIONS'))
pa_pac_opts['padata-value'] = PA_PAC_OPTIONS({'value' : PA_PAC_OPTIONSTypes(set(['resource-based constrained delegation']))}).dump()
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(self.kerberos_TGT['crealm'])
authenticator_data['cname'] = self.kerberos_TGT['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
authenticator_data_enc = self.kerberos_cipher.encrypt(self.kerberos_session_key, 7, Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ap-options'] = APOptions(set())
ap_req['ticket'] = Ticket(self.kerberos_TGT['ticket'])
ap_req['authenticator'] = EncryptedData({'etype': self.kerberos_cipher_type, 'cipher': authenticator_data_enc})
pa_tgs_req = {}
pa_tgs_req['padata-type'] = PaDataType.TGS_REQ.value
pa_tgs_req['padata-value'] = AP_REQ(ap_req).dump()
krb_tgs_body = {}
krb_tgs_body['kdc-options'] = KDCOptions(set(['forwardable','renewable','constrained-delegation', 'canonicalize']))
krb_tgs_body['sname'] = PrincipalName({'name-type': NAME_TYPE.SRV_INST.value, 'name-string': spn_user.get_principalname()})
krb_tgs_body['realm'] = self.usercreds.domain.upper()
krb_tgs_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
krb_tgs_body['nonce'] = secrets.randbits(31)
krb_tgs_body['etype'] = [supp_enc.value] #selecting according to server's preferences
krb_tgs_body['additional-tickets'] = [s4uself_ticket]
krb_tgs_req = {}
krb_tgs_req['pvno'] = krb5_pvno
krb_tgs_req['msg-type'] = MESSAGE_TYPE.KRB_TGS_REQ.value
krb_tgs_req['padata'] = [pa_tgs_req, pa_pac_opts]
krb_tgs_req['req-body'] = KDC_REQ_BODY(krb_tgs_body)
req = TGS_REQ(krb_tgs_req)
logger.debug('[S4U2proxy] Sending request to server')
try:
reply = self.ksoc.sendrecv(req.dump())
except KerberosError as e:
if e.errorcode.value == 16:
logger.error('S4U2proxy: Failed to get S4U2proxy! Error code (16) indicates that delegation is not enabled for this account! Full error: %s' % e)
raise e
logger.debug('[S4U2proxy] Got server reply, decrypting...')
tgs = reply.native
encTGSRepPart = EncTGSRepPart.load(self.kerberos_cipher.decrypt(self.kerberos_session_key, 8, tgs['enc-part']['cipher'])).native
key = Key(encTGSRepPart['key']['keytype'], encTGSRepPart['key']['keyvalue'])
self.ccache.add_tgs(tgs, encTGSRepPart)
logger.debug('[S4U2proxy] Got valid TGS reply')
return tgs, encTGSRepPart, key
def S4U2self(self, user_to_impersonate, supp_enc_methods = [EncryptionType.DES_CBC_CRC,EncryptionType.DES_CBC_MD4,EncryptionType.DES_CBC_MD5,EncryptionType.DES3_CBC_SHA1,EncryptionType.ARCFOUR_HMAC_MD5,EncryptionType.AES256_CTS_HMAC_SHA1_96,EncryptionType.AES128_CTS_HMAC_SHA1_96]):
"""
user_to_impersonate : KerberosTarget class
"""
if not self.kerberos_TGT:
logger.debug('[S4U2self] TGT is not available! Fetching TGT...')
self.get_TGT()
supp_enc = self.usercreds.get_preferred_enctype(supp_enc_methods)
auth_package_name = 'Kerberos'
now = datetime.datetime.now(datetime.timezone.utc)
###### Calculating authenticator data
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(self.kerberos_TGT['crealm'])
authenticator_data['cname'] = self.kerberos_TGT['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
authenticator_data_enc = self.kerberos_cipher.encrypt(self.kerberos_session_key, 7, Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ap-options'] = APOptions(set())
ap_req['ticket'] = Ticket(self.kerberos_TGT['ticket'])
ap_req['authenticator'] = EncryptedData({'etype': self.kerberos_cipher_type, 'cipher': authenticator_data_enc})
pa_data_auth = {}
pa_data_auth['padata-type'] = PaDataType.TGS_REQ.value
pa_data_auth['padata-value'] = AP_REQ(ap_req).dump()
###### Calculating checksum data
S4UByteArray = NAME_TYPE.PRINCIPAL.value.to_bytes(4, 'little', signed = False)
S4UByteArray += user_to_impersonate.username.encode()
S4UByteArray += user_to_impersonate.domain.encode()
S4UByteArray += auth_package_name.encode()
logger.debug('[S4U2self] S4UByteArray: %s' % S4UByteArray.hex())
logger.debug('[S4U2self] S4UByteArray: %s' % S4UByteArray)
chksum_data = _HMACMD5.checksum(self.kerberos_session_key, 17, S4UByteArray)
logger.debug('[S4U2self] chksum_data: %s' % chksum_data.hex())
chksum = {}
chksum['cksumtype'] = int(CKSUMTYPE('HMAC_MD5'))
chksum['checksum'] = chksum_data
###### Filling out PA-FOR-USER data for impersonation
pa_for_user_enc = {}
pa_for_user_enc['userName'] = PrincipalName({'name-type': NAME_TYPE.PRINCIPAL.value, 'name-string': user_to_impersonate.get_principalname()})
pa_for_user_enc['userRealm'] = user_to_impersonate.domain
pa_for_user_enc['cksum'] = Checksum(chksum)
pa_for_user_enc['auth-package'] = auth_package_name
pa_for_user = {}
pa_for_user['padata-type'] = int(PADATA_TYPE('PA-FOR-USER'))
pa_for_user['padata-value'] = PA_FOR_USER_ENC(pa_for_user_enc).dump()
###### Constructing body
krb_tgs_body = {}
krb_tgs_body['kdc-options'] = KDCOptions(set(['forwardable','renewable','canonicalize']))
krb_tgs_body['sname'] = PrincipalName({'name-type': NAME_TYPE.UNKNOWN.value, 'name-string': [self.usercreds.username]})
krb_tgs_body['realm'] = self.usercreds.domain.upper()
krb_tgs_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
krb_tgs_body['nonce'] = secrets.randbits(31)
krb_tgs_body['etype'] = [supp_enc.value] #selecting according to server's preferences
krb_tgs_req = {}
krb_tgs_req['pvno'] = krb5_pvno
krb_tgs_req['msg-type'] = MESSAGE_TYPE.KRB_TGS_REQ.value
krb_tgs_req['padata'] = [pa_data_auth, pa_for_user]
krb_tgs_req['req-body'] = KDC_REQ_BODY(krb_tgs_body)
req = TGS_REQ(krb_tgs_req)
logger.debug('[S4U2self] Sending request to server')
try:
reply = self.ksoc.sendrecv(req.dump())
except KerberosError as e:
if e.errorcode.value == 16:
logger.error('[S4U2self] Failed to get S4U2self! Error code (16) indicates that delegation is not enabled for this account! Full error: %s' % e)
raise e
logger.debug('[S4U2self] Got reply, decrypting...')
tgs = reply.native
encTGSRepPart = EncTGSRepPart.load(self.kerberos_cipher.decrypt(self.kerberos_session_key, 8, tgs['enc-part']['cipher'])).native
key = Key(encTGSRepPart['key']['keytype'], encTGSRepPart['key']['keyvalue'])
self.ccache.add_tgs(tgs, encTGSRepPart)
logger.debug('[S4U2self] Got valid TGS reply')
self.kerberos_TGS = tgs
return tgs, encTGSRepPart, key
def get_TGS(self, spn_user, override_etype = None, is_linux = False):
"""
Requests a TGS ticket for the specified user.
Returns the TGS ticket, end the decrpyted encTGSRepPart.
spn_user: KerberosTarget: the service user you want to get TGS for.
override_etype: None or list of etype values (int) Used mostly for kerberoasting, will override the AP_REQ supported etype values (which is derived from the TGT) to be able to recieve whatever tgs tiecket
"""
logger.debug('[getTGS] Constructing request for user %s' % spn_user.get_formatted_pname())
now = datetime.datetime.now(datetime.timezone.utc)
kdc_req_body = {}
kdc_req_body['kdc-options'] = KDCOptions(set(['forwardable','renewable','renewable_ok', 'canonicalize']))
kdc_req_body['realm'] = spn_user.domain.upper()
kdc_req_body['sname'] = PrincipalName({'name-type': NAME_TYPE.SRV_INST.value, 'name-string': spn_user.get_principalname()})
kdc_req_body['till'] = (now + datetime.timedelta(days=1)).replace(microsecond=0)
kdc_req_body['nonce'] = secrets.randbits(31)
if override_etype:
kdc_req_body['etype'] = override_etype
else:
kdc_req_body['etype'] = [self.kerberos_cipher_type]
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(self.kerberos_TGT['crealm'])
authenticator_data['cname'] = self.kerberos_TGT['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
if is_linux:
ac = AuthenticatorChecksum()
ac.flags = 0
ac.channel_binding = b'\x00'*16
chksum = {}
chksum['cksumtype'] = 0x8003
chksum['checksum'] = ac.to_bytes()
authenticator_data['cksum'] = Checksum(chksum)
authenticator_data['seq-number'] = 0
authenticator_data_enc = self.kerberos_cipher.encrypt(self.kerberos_session_key, 7, Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ap-options'] = APOptions(set())
ap_req['ticket'] = Ticket(self.kerberos_TGT['ticket'])
ap_req['authenticator'] = EncryptedData({'etype': self.kerberos_cipher_type, 'cipher': authenticator_data_enc})
pa_data_1 = {}
pa_data_1['padata-type'] = PaDataType.TGS_REQ.value
pa_data_1['padata-value'] = AP_REQ(ap_req).dump()
kdc_req = {}
kdc_req['pvno'] = krb5_pvno
kdc_req['msg-type'] = MESSAGE_TYPE.KRB_TGS_REQ.value
kdc_req['padata'] = [pa_data_1]
kdc_req['req-body'] = KDC_REQ_BODY(kdc_req_body)
req = TGS_REQ(kdc_req)
logger.debug('[getTGS] Constructing request to server')
rep = self.ksoc.sendrecv(req.dump())
logger.debug('[getTGS] Got reply, decrypting...')
tgs = rep.native
encTGSRepPart = EncTGSRepPart.load(self.kerberos_cipher.decrypt(self.kerberos_session_key, 8, tgs['enc-part']['cipher'])).native
key = Key(encTGSRepPart['key']['keytype'], encTGSRepPart['key']['keyvalue'])
self.ccache.add_tgs(tgs, encTGSRepPart)
logger.debug('[getTGS] Got valid reply')
self.kerberos_TGS = tgs
return tgs, encTGSRepPart, key
def build_apreq(self,
asrep,
session_key,
cipher,
subkey_data,
krb_finished_data,
flags=GSSAPIFlags.GSS_C_MUTUAL_FLAG
| GSSAPIFlags.GSS_C_INTEG_FLAG
| GSSAPIFlags.GSS_C_EXTENDED_ERROR_FLAG):
# TODO: https://www.ietf.org/rfc/rfc4757.txt
#subkey_data = {}
#subkey_data['keytype'] = Enctype.AES256
#subkey_data['keyvalue'] = os.urandom(32)
subkey_cipher = _enctype_table[subkey_data['keytype']]
subkey_key = Key(subkey_cipher.enctype, subkey_data['keyvalue'])
subkey_checksum = _checksum_table[
16] # ChecksumTypes.hmac_sha1_96_aes256
krb_finished_checksum_data = {}
krb_finished_checksum_data['cksumtype'] = 16
krb_finished_checksum_data['checksum'] = subkey_checksum.checksum(
subkey_key, 41, krb_finished_data)
krb_finished_data = {}
krb_finished_data['gss-mic'] = Checksum(krb_finished_checksum_data)
krb_finished = KRB_FINISHED(krb_finished_data).dump()
a = 2
extensions_data = a.to_bytes(
4, byteorder='big', signed=True) + len(krb_finished).to_bytes(
4, byteorder='big', signed=True) + krb_finished
ac = AuthenticatorChecksum()
ac.flags = flags
ac.channel_binding = b'\x00' * 16
chksum = {}
chksum['cksumtype'] = 0x8003
chksum['checksum'] = ac.to_bytes() + extensions_data
tii = LSAP_TOKEN_INFO_INTEGRITY()
tii.Flags = 1
tii.TokenIL = 0x00002000 # Medium integrity
tii.MachineID = bytes.fromhex(
'7e303fffe6bff25146addca4fbddf1b94f1634178eb4528fb2731c669ca23cde')
restriction_data = {}
restriction_data['restriction-type'] = 0
restriction_data['restriction'] = tii.to_bytes()
restriction_data = KERB_AD_RESTRICTION_ENTRY(restriction_data)
x = KERB_AD_RESTRICTION_ENTRYS([restriction_data]).dump()
restrictions = AuthorizationData([{
'ad-type': 141,
'ad-data': x
}]).dump()
now = datetime.datetime.now(datetime.timezone.utc)
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(asrep['crealm'])
authenticator_data['cname'] = asrep['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
authenticator_data['subkey'] = EncryptionKey(subkey_data)
authenticator_data['seq-number'] = 682437742 #??? TODO: check this!
authenticator_data['authorization-data'] = AuthorizationData([{
'ad-type':
1,
'ad-data':
restrictions
}])
authenticator_data['cksum'] = Checksum(chksum)
#print('Authenticator(authenticator_data).dump()')
#print(Authenticator(authenticator_data).dump().hex())
authenticator_data_enc = cipher.encrypt(
session_key, 11,
Authenticator(authenticator_data).dump(), None)
ap_opts = ['mutual-required']
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ticket'] = Ticket(asrep['ticket'])
ap_req['ap-options'] = APOptions(set(ap_opts))
ap_req['authenticator'] = EncryptedData({
'etype':
session_key.enctype,
'cipher':
authenticator_data_enc
})
#pprint('AP_REQ \r\n%s' % AP_REQ(ap_req).native)
#print(AP_REQ(ap_req).dump().hex())
#input()
return AP_REQ(ap_req).dump()
async def S4U2proxy(
self,
s4uself_ticket,
spn_user,
supp_enc_methods=[
EncryptionType.DES_CBC_CRC, EncryptionType.DES_CBC_MD4,
EncryptionType.DES_CBC_MD5, EncryptionType.DES3_CBC_SHA1,
EncryptionType.ARCFOUR_HMAC_MD5,
EncryptionType.AES256_CTS_HMAC_SHA1_96,
EncryptionType.AES128_CTS_HMAC_SHA1_96
]):
now = datetime.datetime.now(datetime.timezone.utc)
supp_enc = self.usercreds.get_preferred_enctype(supp_enc_methods)
pa_pac_opts = {}
pa_pac_opts['padata-type'] = int(PADATA_TYPE('PA-PAC-OPTIONS'))
pa_pac_opts['padata-value'] = PA_PAC_OPTIONS({
'value':
PA_PAC_OPTIONSTypes(set(['resource-based constrained delegation']))
}).dump()
authenticator_data = {}
authenticator_data['authenticator-vno'] = krb5_pvno
authenticator_data['crealm'] = Realm(self.kerberos_TGT['crealm'])
authenticator_data['cname'] = self.kerberos_TGT['cname']
authenticator_data['cusec'] = now.microsecond
authenticator_data['ctime'] = now.replace(microsecond=0)
authenticator_data_enc = self.kerberos_cipher.encrypt(
self.kerberos_session_key, 7,
Authenticator(authenticator_data).dump(), None)
ap_req = {}
ap_req['pvno'] = krb5_pvno
ap_req['msg-type'] = MESSAGE_TYPE.KRB_AP_REQ.value
ap_req['ap-options'] = APOptions(set())
ap_req['ticket'] = Ticket(self.kerberos_TGT['ticket'])
ap_req['authenticator'] = EncryptedData({
'etype':
self.kerberos_cipher_type,
'cipher':
authenticator_data_enc
})
pa_tgs_req = {}
pa_tgs_req['padata-type'] = PaDataType.TGS_REQ.value
pa_tgs_req['padata-value'] = AP_REQ(ap_req).dump()
krb_tgs_body = {}
#krb_tgs_body['kdc-options'] = KDCOptions(set(['forwardable','forwarded','renewable','renewable-ok', 'canonicalize']))
krb_tgs_body['kdc-options'] = KDCOptions(
set([
'forwardable', 'renewable', 'constrained-delegation',
'canonicalize'
]))
krb_tgs_body['sname'] = PrincipalName({
'name-type':
NAME_TYPE.SRV_INST.value,
'name-string':
spn_user.get_principalname()
})
krb_tgs_body['realm'] = self.usercreds.domain.upper()
krb_tgs_body['till'] = (now + datetime.timedelta(days=1)).replace(
microsecond=0)
krb_tgs_body['nonce'] = secrets.randbits(31)
krb_tgs_body['etype'] = [
supp_enc.value
] #selecting according to server's preferences
krb_tgs_body['additional-tickets'] = [s4uself_ticket]
krb_tgs_req = {}
krb_tgs_req['pvno'] = krb5_pvno
krb_tgs_req['msg-type'] = MESSAGE_TYPE.KRB_TGS_REQ.value
krb_tgs_req['padata'] = [pa_tgs_req, pa_pac_opts]
krb_tgs_req['req-body'] = KDC_REQ_BODY(krb_tgs_body)
req = TGS_REQ(krb_tgs_req)
reply = await self.ksoc.sendrecv(req.dump())
if reply.name == 'KRB_ERROR':
if reply.native['error-code'] == 16:
logger.error(
'S4U2proxy: Failed to get S4U2proxy! Error code (16) indicates that delegation is not enabled for this account!'
)
raise Exception('S4U2proxy failed! %s' % str(reply))
async def authenticate(self,
authData,
flags=None,
seq_number=0,
cb_data=None):
"""
This function is called (multiple times depending on the flags) to perform authentication.
"""
try:
if self.kc is None:
_, err = await self.setup_kc()
if err is not None:
return None, None, err
if self.iterations == 0:
self.seq_number = 0
self.iterations += 1
try:
#check TGS first, maybe ccache already has what we need
for target in self.ccred.ccache.list_targets():
# just printing this to debug...
logger.debug('CCACHE SPN record: %s' % target)
tgs, encpart, self.session_key = await self.kc.get_TGS(
self.spn)
self.from_ccache = True
except:
tgt = await self.kc.get_TGT(
override_etype=self.preferred_etypes)
tgs, encpart, self.session_key = await self.kc.get_TGS(
self.spn) #, override_etype = self.preferred_etypes)
#self.expected_server_seq_number = encpart.get('nonce', seq_number)
ap_opts = []
if ChecksumFlags.GSS_C_MUTUAL_FLAG in self.flags or ChecksumFlags.GSS_C_DCE_STYLE in self.flags:
if ChecksumFlags.GSS_C_MUTUAL_FLAG in self.flags:
ap_opts.append('mutual-required')
if self.from_ccache is False:
apreq = self.kc.construct_apreq(
tgs,
encpart,
self.session_key,
flags=self.flags,
seq_number=self.seq_number,
ap_opts=ap_opts,
cb_data=cb_data)
else:
apreq = self.kc.construct_apreq_from_ticket(
Ticket(tgs['ticket']).dump(),
self.session_key,
tgs['crealm'],
tgs['cname']['name-string'][0],
flags=self.flags,
seq_number=self.seq_number,
ap_opts=ap_opts,
cb_data=cb_data)
return apreq, True, None
else:
#no mutual or dce auth will take one step only
if self.from_ccache is False:
apreq = self.kc.construct_apreq(
tgs,
encpart,
self.session_key,
flags=self.flags,
seq_number=self.seq_number,
ap_opts=[],
cb_data=cb_data)
else:
apreq = self.kc.construct_apreq_from_ticket(
Ticket(tgs['ticket']).dump(),
self.session_key,
tgs['crealm'],
tgs['cname']['name-string'][0],
flags=self.flags,
seq_number=self.seq_number,
ap_opts=ap_opts,
cb_data=cb_data)
self.gssapi = get_gssapi(self.session_key)
return apreq, False, None
else:
self.iterations += 1
if ChecksumFlags.GSS_C_DCE_STYLE in self.flags:
# adata = authData[16:]
# if ChecksumFlags.GSS_C_DCE_STYLE in self.flags:
# adata = authData
raise Exception('DCE auth Not implemented!')
# at this point we are dealing with mutual authentication
# This means that the server sent back an AP-rep wrapped in a token
# The APREP contains a new session key we'd need to update and a seq-number
# that is expected the server will use for future communication.
# For mutual auth we dont need to reply anything after this step,
# but for DCE auth a reply is expected. TODO
# converting the token to aprep
token = KRB5_MECH_INDEP_TOKEN.from_bytes(authData)
if token.data[:2] != b'\x02\x00':
raise Exception('Unexpected token type! %s' %
token.data[:2].hex())
aprep = AP_REP.load(token.data[2:]).native
# decrypting aprep
cipher = _enctype_table[int(aprep['enc-part']['etype'])]()
cipher_text = aprep['enc-part']['cipher']
temp = cipher.decrypt(self.session_key, 12, cipher_text)
enc_part = EncAPRepPart.load(temp).native
#updating session key, gssapi
self.session_key = Key(int(enc_part['subkey']['keytype']),
enc_part['subkey']['keyvalue'])
#self.seq_number = enc_part.get('seq-number', 0)
self.gssapi = get_gssapi(self.session_key)
return b'', False, None
except Exception as e:
return None, None, e
