From: Joseph Sutton Date: Tue, 19 Oct 2021 07:02:45 +0000 (+1300) Subject: CVE-2020-25719 tests/krb5: Add principal aliasing test X-Git-Tag: samba-4.13.14~172 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f839cc40af6115ea84bcac5c7fa84d616b181d83;p=thirdparty%2Fsamba.git CVE-2020-25719 tests/krb5: Add principal aliasing test BUG: https://bugzilla.samba.org/show_bug.cgi?id=14686 Signed-off-by: Joseph Sutton Reviewed-by: Andrew Bartlett --- diff --git a/python/samba/tests/krb5/alias_tests.py b/python/samba/tests/krb5/alias_tests.py new file mode 100755 index 00000000000..60213845a44 --- /dev/null +++ b/python/samba/tests/krb5/alias_tests.py @@ -0,0 +1,201 @@ +#!/usr/bin/env python3 +# Unix SMB/CIFS implementation. +# Copyright (C) Stefan Metzmacher 2020 +# Copyright (C) 2021 Catalyst.Net Ltd +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . +# + +import sys +import os + +import ldb + +from samba.tests import delete_force +import samba.tests.krb5.kcrypto as kcrypto +from samba.tests.krb5.kdc_base_test import KDCBaseTest +from samba.tests.krb5.rfc4120_constants import ( + AES256_CTS_HMAC_SHA1_96, + ARCFOUR_HMAC_MD5, + KDC_ERR_CLIENT_NAME_MISMATCH, + NT_PRINCIPAL, +) + +sys.path.insert(0, 'bin/python') +os.environ['PYTHONUNBUFFERED'] = '1' + +global_asn1_print = False +global_hexdump = False + + +class AliasTests(KDCBaseTest): + def test_dc_alias_rename(self): + self._run_dc_alias(action='rename') + + def test_dc_alias_delete(self): + self._run_dc_alias(action='delete') + + def _run_dc_alias(self, action=None): + target_creds = self.get_dc_creds() + target_name = target_creds.get_username()[:-1] + + self._run_alias(target_name, lambda: target_creds, action=action) + + def test_create_alias_rename(self): + self._run_create_alias(action='rename') + + def test_create_alias_delete(self): + self._run_create_alias(action='delete') + + def _run_create_alias(self, action=None): + target_name = self.get_new_username() + + def create_target(): + samdb = self.get_samdb() + + realm = samdb.domain_dns_name().lower() + + hostname = f'{target_name}.{realm}' + spn = f'ldap/{hostname}' + + details = { + 'dNSHostName': hostname + } + + creds, fn = self.create_account( + samdb, + target_name, + account_type=self.AccountType.COMPUTER, + spn=spn, + additional_details=details) + + return creds + + self._run_alias(target_name, create_target, action=action) + + def _run_alias(self, target_name, target_creds_fn, action=None): + samdb = self.get_samdb() + + mach_name = self.get_new_username() + + # Create a machine account. + mach_creds, mach_dn = self.create_account( + samdb, mach_name, account_type=self.AccountType.COMPUTER) + self.addCleanup(delete_force, samdb, mach_dn) + + mach_sid = self.get_objectSid(samdb, mach_dn) + realm = mach_creds.get_realm() + + # The account salt doesn't change when the account is renamed. + old_salt = mach_creds.get_salt() + mach_creds.set_forced_salt(old_salt) + + # Rename the account to alias with the target account. + msg = ldb.Message(ldb.Dn(samdb, mach_dn)) + msg['sAMAccountName'] = ldb.MessageElement(target_name, + ldb.FLAG_MOD_REPLACE, + 'sAMAccountName') + samdb.modify(msg) + mach_creds.set_username(target_name) + + # Get a TGT for the machine account. + tgt = self.get_tgt(mach_creds, kdc_options='0', fresh=True) + + # Check the PAC. + pac_data = self.get_pac_data(tgt.ticket_private['authorization-data']) + + upn = f'{target_name}@{realm.lower()}' + + self.assertEqual(target_name, str(pac_data.account_name)) + self.assertEqual(mach_sid, pac_data.account_sid) + self.assertEqual(target_name, pac_data.logon_name) + self.assertEqual(upn, pac_data.upn) + self.assertEqual(realm, pac_data.domain_name) + + # Rename or delete the machine account. + if action == 'rename': + mach_name2 = self.get_new_username() + + msg = ldb.Message(ldb.Dn(samdb, mach_dn)) + msg['sAMAccountName'] = ldb.MessageElement(mach_name2, + ldb.FLAG_MOD_REPLACE, + 'sAMAccountName') + samdb.modify(msg) + elif action == 'delete': + samdb.delete(mach_dn) + else: + self.fail(action) + + # Get the credentials for the target account. + target_creds = target_creds_fn() + + # Look up the DNS host name of the target account. + target_dn = target_creds.get_dn() + res = samdb.search(target_dn, + scope=ldb.SCOPE_BASE, + attrs=['dNSHostName']) + target_hostname = str(res[0].get('dNSHostName', idx=0)) + + sname = self.PrincipalName_create(name_type=NT_PRINCIPAL, + names=['ldap', target_hostname]) + target_cname = self.PrincipalName_create(name_type=NT_PRINCIPAL, + names=[target_name]) + + target_decryption_key = self.TicketDecryptionKey_from_creds( + target_creds) + + authenticator_subkey = self.RandomKey(kcrypto.Enctype.AES256) + + etypes = (AES256_CTS_HMAC_SHA1_96, ARCFOUR_HMAC_MD5) + + def generate_s4u2self_padata(_kdc_exchange_dict, + _callback_dict, + req_body): + padata = self.PA_S4U2Self_create(name=target_cname, + realm=realm, + tgt_session_key=tgt.session_key, + ctype=None) + return [padata], req_body + + expected_error_mode = KDC_ERR_CLIENT_NAME_MISMATCH + + # Make a request using S4U2Self. The request should fail. + kdc_exchange_dict = self.tgs_exchange_dict( + expected_crealm=realm, + expected_cname=target_cname, + expected_srealm=realm, + expected_sname=sname, + ticket_decryption_key=target_decryption_key, + generate_padata_fn=generate_s4u2self_padata, + expected_error_mode=expected_error_mode, + check_error_fn=self.generic_check_kdc_error, + check_kdc_private_fn=self.generic_check_kdc_private, + tgt=tgt, + authenticator_subkey=authenticator_subkey, + kdc_options='0', + expect_pac=True) + + rep = self._generic_kdc_exchange(kdc_exchange_dict, + cname=None, + realm=realm, + sname=sname, + etypes=etypes) + self.check_error_rep(rep, expected_error_mode) + + +if __name__ == '__main__': + global_asn1_print = False + global_hexdump = False + import unittest + unittest.main() diff --git a/python/samba/tests/krb5/rfc4120_constants.py b/python/samba/tests/krb5/rfc4120_constants.py index 39bb2db8e32..b643185f767 100644 --- a/python/samba/tests/krb5/rfc4120_constants.py +++ b/python/samba/tests/krb5/rfc4120_constants.py @@ -81,6 +81,7 @@ KDC_ERR_SKEW = 37 KDC_ERR_MODIFIED = 41 KDC_ERR_INAPP_CKSUM = 50 KDC_ERR_GENERIC = 60 +KDC_ERR_CLIENT_NAME_MISMATCH = 75 KDC_ERR_UNKNOWN_CRITICAL_FAST_OPTIONS = 93 # Extended error types diff --git a/python/samba/tests/usage.py b/python/samba/tests/usage.py index 7d11b6b4617..5cae7429985 100644 --- a/python/samba/tests/usage.py +++ b/python/samba/tests/usage.py @@ -105,6 +105,7 @@ EXCLUDE_USAGE = { 'python/samba/tests/krb5/rodc_tests.py', 'python/samba/tests/krb5/salt_tests.py', 'python/samba/tests/krb5/spn_tests.py', + 'python/samba/tests/krb5/alias_tests.py', } EXCLUDE_HELP = { diff --git a/selftest/knownfail_heimdal_kdc b/selftest/knownfail_heimdal_kdc index f141efa86e5..5e0d958ee59 100644 --- a/selftest/knownfail_heimdal_kdc +++ b/selftest/knownfail_heimdal_kdc @@ -271,3 +271,10 @@ ^samba.tests.krb5.kdc_tgs_tests.samba.tests.krb5.kdc_tgs_tests.KdcTgsTests.test_remove_pac_client_no_auth_data_required ^samba.tests.krb5.kdc_tgs_tests.samba.tests.krb5.kdc_tgs_tests.KdcTgsTests.test_remove_pac_service_no_auth_data_required ^samba.tests.krb5.kdc_tgs_tests.samba.tests.krb5.kdc_tgs_tests.KdcTgsTests.test_request_no_pac +# +# Alias tests +# +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_create_alias_delete +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_create_alias_rename +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_dc_alias_delete +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_dc_alias_rename diff --git a/selftest/knownfail_mit_kdc b/selftest/knownfail_mit_kdc index 8612d05b3da..4441be9d203 100644 --- a/selftest/knownfail_mit_kdc +++ b/selftest/knownfail_mit_kdc @@ -386,3 +386,10 @@ samba.tests.krb5.as_canonicalization_tests.samba.tests.krb5.as_canonicalization_ ^samba.tests.krb5.spn_tests.samba.tests.krb5.spn_tests.SpnTests.test_spn_3_part_instance_spn_computer ^samba.tests.krb5.spn_tests.samba.tests.krb5.spn_tests.SpnTests.test_spn_3_part_our_domain_spn_computer ^samba.tests.krb5.spn_tests.samba.tests.krb5.spn_tests.SpnTests.test_spn_3_part_our_realm_spn_computer +# +# Alias tests +# +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_create_alias_delete +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_create_alias_rename +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_dc_alias_delete +^samba.tests.krb5.alias_tests.samba.tests.krb5.alias_tests.AliasTests.test_dc_alias_rename diff --git a/source4/selftest/tests.py b/source4/selftest/tests.py index 44bb50267c4..53721d1afda 100755 --- a/source4/selftest/tests.py +++ b/source4/selftest/tests.py @@ -1478,6 +1478,16 @@ planpythontestsuite( 'FAST_SUPPORT': have_fast_support, 'TKT_SIG_SUPPORT': tkt_sig_support }) +planpythontestsuite( + "ad_dc", + "samba.tests.krb5.alias_tests", + environ={ + 'ADMIN_USERNAME': '$USERNAME', + 'ADMIN_PASSWORD': '$PASSWORD', + 'STRICT_CHECKING': '0', + 'FAST_SUPPORT': have_fast_support, + 'TKT_SIG_SUPPORT': tkt_sig_support + }) for env in [ 'vampire_dc',