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[LDAP] Add custom cbt_value #1977

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[LDAP] Add custom cbt_value #1977

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52 changes: 26 additions & 26 deletions impacket/ldap/ldap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,7 @@ def __init__(self, url, baseDN='', dstIp=None, signing=True):
raise LDAPSessionError(errorString="Unknown URL prefix: '%s'" % url)

self.__binded = False
self.__channel_binding_value = None

### SASL Auth LDAP Signing arguments
self.sequenceNumber = 0
Expand Down Expand Up @@ -141,26 +142,25 @@ def __init__(self, url, baseDN='', dstIp=None, signing=True):
self._socket.connect(sa)
self._socket.do_handshake()

def generateChannelBindingValue(self):
# From: https://github.com/ly4k/ldap3/commit/87f5760e5a68c2f91eac8ba375f4ea3928e2b9e0#diff-c782b790cfa0a948362bf47d72df8ddd6daac12e5757afd9d371d89385b27ef6R1383
from hashlib import md5
# Ugly but effective, to get the digest of the X509 DER in bytes
peer_cert_digest_str = self._socket.get_peer_certificate().digest('sha256').decode()
peer_cert_digest_bytes = bytes.fromhex(peer_cert_digest_str.replace(':', ''))

channel_binding_struct = b''
initiator_address = b'\x00'*8
acceptor_address = b'\x00'*8

# https://datatracker.ietf.org/doc/html/rfc5929#section-4
application_data_raw = b'tls-server-end-point:' + peer_cert_digest_bytes
len_application_data = len(application_data_raw).to_bytes(4, byteorder='little', signed = False)
application_data = len_application_data
application_data += application_data_raw
channel_binding_struct += initiator_address
channel_binding_struct += acceptor_address
channel_binding_struct += application_data
return md5(channel_binding_struct).digest()
# From: https://github.com/ly4k/ldap3/commit/87f5760e5a68c2f91eac8ba375f4ea3928e2b9e0#diff-c782b790cfa0a948362bf47d72df8ddd6daac12e5757afd9d371d89385b27ef6R1383
from hashlib import md5
# Ugly but effective, to get the digest of the X509 DER in bytes
peer_cert_digest_str = self._socket.get_peer_certificate().digest('sha256').decode()
peer_cert_digest_bytes = bytes.fromhex(peer_cert_digest_str.replace(':', ''))

channel_binding_struct = b''
initiator_address = b'\x00'*8
acceptor_address = b'\x00'*8

# https://datatracker.ietf.org/doc/html/rfc5929#section-4
application_data_raw = b'tls-server-end-point:' + peer_cert_digest_bytes
len_application_data = len(application_data_raw).to_bytes(4, byteorder='little', signed = False)
application_data = len_application_data
application_data += application_data_raw
channel_binding_struct += initiator_address
channel_binding_struct += acceptor_address
channel_binding_struct += application_data
self.__channel_binding_value = md5(channel_binding_struct).digest()

def kerberosLogin(self, user, password, domain='', lmhash='', nthash='', aesKey='', kdcHost=None, TGT=None,
TGS=None, useCache=True):
Expand Down Expand Up @@ -268,8 +268,8 @@ def kerberosLogin(self, user, password, domain='', lmhash='', nthash='', aesKey=

# If TLS is used, setup channel binding

if self._SSL:
chkField['Bnd'] = self.generateChannelBindingValue()
if self._SSL and self.__channel_binding_value is not None:
chkField['Bnd'] = self.__channel_binding_value
if self.__signing:
chkField['Flags'] |= GSS_C_CONF_FLAG
chkField['Flags'] |= GSS_C_INTEG_FLAG
Expand Down Expand Up @@ -372,8 +372,8 @@ def login(self, user='', password='', domain='', lmhash='', nthash='', authentic

# If TLS is used, setup channel binding
channel_binding_value = b''
if self._SSL:
channel_binding_value = self.generateChannelBindingValue()
if self._SSL and self.__channel_binding_value is not None:
channel_binding_value = self.__channel_binding_value

# NTLM Auth
type3, exportedSessionKey = getNTLMSSPType3(negotiate, bytes(type2), user, password, domain, lmhash, nthash, channel_binding_value=channel_binding_value)
Expand Down Expand Up @@ -418,8 +418,8 @@ def login(self, user='', password='', domain='', lmhash='', nthash='', authentic

# channel binding
channel_binding_value = b''
if self._SSL:
channel_binding_value = self.generateChannelBindingValue()
if self._SSL and self.__channel_binding_value is not None:
channel_binding_value = self.__channel_binding_value

# NTLM Auth
type3, exportedSessionKey = getNTLMSSPType3(negotiate, type2, user, password, domain, lmhash, nthash, service='ldap', version=self.version, use_ntlmv2=True, channel_binding_value=channel_binding_value)
Expand Down