The branch, master has been updated
via 9945f3e3548 CVE-2020-1472(ZeroLogon): s4 torture rpc: repeated
bytes in client challenge
via 4b262b03e1e CVE-2020-1472(ZeroLogon): s4 torture rpc: Test empty
machine acct pwd
via d1790a0b5ae CVE-2020-1472(ZeroLogon): docs-xml: document 'server
require schannel:COMPUTERACCOUNT'
via b8e4b0f4306 CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: log
warnings about unsecure configurations
via b74017d2dd1 CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon:
support "server require schannel:WORKSTATION$ = no"
via 9ef5b63e7a1 CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon:
refactor dcesrv_netr_creds_server_step_check()
via ca8a0098ac2 CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: log
warnings about unsecure configurations
via f9b772bf286 CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon:
support "server require schannel:WORKSTATION$ = no"
via be8e6394990 CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon:
refactor dcesrv_netr_creds_server_step_check()
via 82d41977a8b CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon:
protect netr_ServerPasswordSet2 against unencrypted passwords
via 9ec8b59bdea CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: Fix
mem leak onto p->mem_ctx in error path of _netr_ServerPasswordSet2().
via d8a6e6549c1 CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon:
protect netr_ServerPasswordSet2 against unencrypted passwords
via d3123858fb5 CVE-2020-1472(ZeroLogon): libcli/auth: reject weak
client challenges in netlogon_creds_server_init()
via 53528c71ffd CVE-2020-1472(ZeroLogon): libcli/auth: add
netlogon_creds_is_random_challenge() to avoid weak values
via 74eb448adf7 CVE-2020-1472(ZeroLogon): s4:rpc_server:netlogon: make
use of netlogon_creds_random_challenge()
via caba2d8082d CVE-2020-1472(ZeroLogon): s3:rpc_server:netlogon: make
use of netlogon_creds_random_challenge()
via 46642fd32d9 CVE-2020-1472(ZeroLogon): libcli/auth: make use of
netlogon_creds_random_challenge() in netlogon_creds_cli.c
via 355efadc6a1 CVE-2020-1472(ZeroLogon): s4:torture/rpc: make use of
netlogon_creds_random_challenge()
via b813cdcac37 CVE-2020-1472(ZeroLogon): libcli/auth: add
netlogon_creds_random_challenge()
from 380938b00fb nt_printing_ads: add missing printShareName attribute
when publishing printers
https://git.samba.org/?p=samba.git;a=shortlog;h=master
- Log -----------------------------------------------------------------
commit 9945f3e3548657c33cc2e5ef97eedd1dfe2edf71
Author: Gary Lockyer <g...@catalyst.net.nz>
Date: Fri Sep 18 15:57:34 2020 +1200
CVE-2020-1472(ZeroLogon): s4 torture rpc: repeated bytes in client challenge
Ensure that client challenges with the first 5 bytes identical are
rejected.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Gary Lockyer <g...@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <me...@samba.org>
Autobuild-User(master): Stefan Metzmacher <me...@samba.org>
Autobuild-Date(master): Fri Sep 18 14:13:17 UTC 2020 on sn-devel-184
commit 4b262b03e1e8285c399338895832a115953d3f23
Author: Gary Lockyer <g...@catalyst.net.nz>
Date: Fri Sep 18 12:39:54 2020 +1200
CVE-2020-1472(ZeroLogon): s4 torture rpc: Test empty machine acct pwd
Ensure that an empty machine account password can't be set by
netr_ServerPasswordSet2
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Gary Lockyer <g...@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <me...@samba.org>
commit d1790a0b5ae7160f6707c6c4fbf2217b251584ea
Author: Stefan Metzmacher <me...@samba.org>
Date: Thu Sep 17 17:27:54 2020 +0200
CVE-2020-1472(ZeroLogon): docs-xml: document 'server require
schannel:COMPUTERACCOUNT'
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit b8e4b0f4306e2d0b4b7c7c443d97abf46d7f9aca
Author: Günther Deschner <g...@samba.org>
Date: Thu Sep 17 14:42:52 2020 +0200
CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: log warnings about
unsecure configurations
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Pair-Programmed-With: Stefan Metzmacher <me...@samba.org>
Signed-off-by: Günther Deschner <g...@samba.org>
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit b74017d2dd15006f4bec899aa38191a3b44800e4
Author: Günther Deschner <g...@samba.org>
Date: Thu Sep 17 14:23:16 2020 +0200
CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: support "server require
schannel:WORKSTATION$ = no"
This allows to add expections for individual workstations, when using
"server schannel = yes".
"server schannel = auto" is very insecure and will be removed soon.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Pair-Programmed-With: Stefan Metzmacher <me...@samba.org>
Signed-off-by: Günther Deschner <g...@samba.org>
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 9ef5b63e7a169154401e58f7a29ed25443e5318f
Author: Günther Deschner <g...@samba.org>
Date: Thu Sep 17 14:57:22 2020 +0200
CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: refactor
dcesrv_netr_creds_server_step_check()
We should debug more details about the failing request.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Pair-Programmed-With: Stefan Metzmacher <me...@samba.org>
Signed-off-by: Günther Deschner <g...@samba.org>
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit ca8a0098ac207123a47b8b8f8602599d71d739db
Author: Stefan Metzmacher <me...@samba.org>
Date: Thu Sep 17 13:37:26 2020 +0200
CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: log warnings about
unsecure configurations
This should give admins wawrnings until they have a secure
configuration.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Ralph Boehme <s...@samba.org>
Reviewed-by: Günther Deschner <g...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit f9b772bf286b7bde6a29cb8d7bbd241638daf5e7
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 10:56:53 2020 +0200
CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: support "server require
schannel:WORKSTATION$ = no"
This allows to add expections for individual workstations, when using
"server schannel = yes".
"server schannel = auto" is very insecure and will be removed soon.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit be8e63949908d8c10d490c8cd0119df4fb917eeb
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 10:18:45 2020 +0200
CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: refactor
dcesrv_netr_creds_server_step_check()
We should debug more details about the failing request.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 82d41977a8bef426396e3e00833d55711a55f372
Author: Jeremy Allison <j...@samba.org>
Date: Wed Sep 16 12:53:50 2020 -0700
CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: protect
netr_ServerPasswordSet2 against unencrypted passwords
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Pair-Programmed-With: Stefan Metzmacher <me...@samba.org>
Signed-off-by: Jeremy Allison <j...@samba.org>
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 9ec8b59bdea19c99099a718ff9e04cd854563e11
Author: Jeremy Allison <j...@samba.org>
Date: Wed Sep 16 12:48:21 2020 -0700
CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: Fix mem leak onto
p->mem_ctx in error path of _netr_ServerPasswordSet2().
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Jeremy Allison <j...@samba.org>
Reviewed-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit d8a6e6549c185daa26852d6d85f475cddfb3083a
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 19:20:25 2020 +0200
CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: protect
netr_ServerPasswordSet2 against unencrypted passwords
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit d3123858fb59046e826cf2c7ec2a3839e6508624
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:17:29 2020 +0200
CVE-2020-1472(ZeroLogon): libcli/auth: reject weak client challenges in
netlogon_creds_server_init()
This implements the note from MS-NRPC 3.1.4.1 Session-Key Negotiation:
7. If none of the first 5 bytes of the client challenge is unique, the
server MUST fail session-key negotiation without further processing of
the following steps.
It lets ./zerologon_tester.py from
https://github.com/SecuraBV/CVE-2020-1472.git
report: "Attack failed. Target is probably patched."
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 53528c71ffdb3377c4e73ac596c8507bc3898e83
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:15:26 2020 +0200
CVE-2020-1472(ZeroLogon): libcli/auth: add
netlogon_creds_is_random_challenge() to avoid weak values
This is the check Windows is using, so we won't generate challenges,
which are rejected by Windows DCs (and future Samba DCs).
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 74eb448adf7fb638fe925eab87a2dbfe9c002cc0
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:10:53 2020 +0200
CVE-2020-1472(ZeroLogon): s4:rpc_server:netlogon: make use of
netlogon_creds_random_challenge()
This is not strictly needed, but makes things more clear.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit caba2d8082d4b038aa59954b6e812612c2ecc0e1
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:10:53 2020 +0200
CVE-2020-1472(ZeroLogon): s3:rpc_server:netlogon: make use of
netlogon_creds_random_challenge()
This is not strictly needed, but makes things more clear.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 46642fd32d91b008615b859cfdf946f63b1ca0aa
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:08:38 2020 +0200
CVE-2020-1472(ZeroLogon): libcli/auth: make use of
netlogon_creds_random_challenge() in netlogon_creds_cli.c
This will avoid getting rejected by the server if we generate
a weak challenge.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit 355efadc6a18ffaaef2e4786e35e89780b10bccc
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:07:30 2020 +0200
CVE-2020-1472(ZeroLogon): s4:torture/rpc: make use of
netlogon_creds_random_challenge()
This will avoid getting flakey tests once our server starts to
reject weak challenges.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
commit b813cdcac377210c3ab18e0d0a0c1a76870b1d74
Author: Stefan Metzmacher <me...@samba.org>
Date: Wed Sep 16 16:04:57 2020 +0200
CVE-2020-1472(ZeroLogon): libcli/auth: add netlogon_creds_random_challenge()
It's good to have just a single isolated function that will generate
random challenges, in future we can add some logic in order to
avoid weak values, which are likely to be rejected by a server.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497
Signed-off-by: Stefan Metzmacher <me...@samba.org>
Reviewed-by: Gary Lockyer <g...@catalyst.net.nz>
-----------------------------------------------------------------------
Summary of changes:
docs-xml/smbdotconf/security/serverschannel.xml | 69 +++-
libcli/auth/credentials.c | 44 ++-
libcli/auth/netlogon_creds_cli.c | 3 +-
libcli/auth/proto.h | 3 +
libcli/auth/wscript_build | 2 +-
source3/rpc_server/netlogon/srv_netlog_nt.c | 212 +++++++++++-
source4/rpc_server/netlogon/dcerpc_netlogon.c | 175 +++++++++-
source4/torture/rpc/lsa.c | 2 +-
source4/torture/rpc/netlogon.c | 434 ++++++++++++++++++++----
9 files changed, 835 insertions(+), 109 deletions(-)
Changeset truncated at 500 lines:
diff --git a/docs-xml/smbdotconf/security/serverschannel.xml
b/docs-xml/smbdotconf/security/serverschannel.xml
index 489492d79b1..b682d086f76 100644
--- a/docs-xml/smbdotconf/security/serverschannel.xml
+++ b/docs-xml/smbdotconf/security/serverschannel.xml
@@ -7,26 +7,65 @@
<description>
<para>
- This option is deprecated with Samba 4.8 and will be removed in future.
- At the same time the default changed to yes, which will be the
- hardcoded behavior in future. If you have the need for the behavior of
"auto"
- to be kept, please file a bug at https://bugzilla.samba.org.
+ This option is deprecated and will be removed in future,
+ as it is a security problem if not set to "yes" (which will be
+ the hardcoded behavior in future).
</para>
<para>
- This controls whether the server offers or even demands the use of the
netlogon schannel.
- <smbconfoption name="server schannel">no</smbconfoption> does not offer
the schannel, <smbconfoption
- name="server schannel">auto</smbconfoption> offers the schannel but
does not enforce it, and <smbconfoption
- name="server schannel">yes</smbconfoption> denies access if the client
is not able to speak netlogon schannel.
- This is only the case for Windows NT4 before SP4.
- </para>
-
+ Samba will complain in the log files at log level 0,
+ about the security problem if the option is not set to "yes".
+ </para>
<para>
- Please note that with this set to <literal>no</literal>, you will have
to apply the WindowsXP
- <filename>WinXP_SignOrSeal.reg</filename> registry patch found in the
docs/registry subdirectory of the Samba distribution tarball.
- </para>
+ See CVE-2020-1472(ZeroLogon)
https://bugzilla.samba.org/show_bug.cgi?id=14497
+ </para>
+
+ <para>If you still have legacy domain members use the <smbconfoption
name="server require schannel:COMPUTERACCOUNT"/> option.
+ </para>
+
+ <para>This option yields precedence to the <smbconfoption name="server
require schannel:COMPUTERACCOUNT"/> option.</para>
+
</description>
<value type="default">yes</value>
-<value type="example">auto</value>
+</samba:parameter>
+
+<samba:parameter name="server require schannel:COMPUTERACCOUNT"
+ context="G"
+ type="string"
+ xmlns:samba="http://www.samba.org/samba/DTD/samba-doc";>
+<description>
+
+ <para>If you still have legacy domain members, which required "server
schannel = auto" before,
+ it is possible to specify explicit expection per computer account
+ by using 'server require schannel:COMPUTERACCOUNT = no' as option.
+ Note that COMPUTERACCOUNT has to be the sAMAccountName value of
+ the computer account (including the trailing '$' sign).
+ </para>
+
+ <para>
+ Samba will complain in the log files at log level 0,
+ about the security problem if the option is not set to "no",
+ but the related computer is actually using the netlogon
+ secure channel (schannel) feature.
+ </para>
+
+ <para>
+ Samba will warn in the log files at log level 5,
+ if a setting is still needed for the specified computer account.
+ </para>
+
+ <para>
+ See CVE-2020-1472(ZeroLogon)
https://bugzilla.samba.org/show_bug.cgi?id=14497
+ </para>
+
+ <para>This option takes precedence to the <smbconfoption name="server
schannel"/> option.</para>
+
+ <programlisting>
+ server require schannel:LEGACYCOMPUTER1$ = no
+ server require schannel:NASBOX$ = no
+ server require schannel:LEGACYCOMPUTER2$ = no
+ </programlisting>
+</description>
+
</samba:parameter>
diff --git a/libcli/auth/credentials.c b/libcli/auth/credentials.c
index c541eeff470..23339d98bfa 100644
--- a/libcli/auth/credentials.c
+++ b/libcli/auth/credentials.c
@@ -24,6 +24,7 @@
#include "system/time.h"
#include "libcli/auth/libcli_auth.h"
#include "../libcli/security/dom_sid.h"
+#include "lib/util/util_str_escape.h"
#ifndef HAVE_GNUTLS_AES_CFB8
#include "lib/crypto/aes.h"
@@ -33,6 +34,33 @@
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>
+bool netlogon_creds_is_random_challenge(const struct netr_Credential
*challenge)
+{
+ /*
+ * If none of the first 5 bytes of the client challenge is unique, the
+ * server MUST fail session-key negotiation without further processing
+ * of the following steps.
+ */
+
+ if (challenge->data[1] == challenge->data[0] &&
+ challenge->data[2] == challenge->data[0] &&
+ challenge->data[3] == challenge->data[0] &&
+ challenge->data[4] == challenge->data[0])
+ {
+ return false;
+ }
+
+ return true;
+}
+
+void netlogon_creds_random_challenge(struct netr_Credential *challenge)
+{
+ ZERO_STRUCTP(challenge);
+ while (!netlogon_creds_is_random_challenge(challenge)) {
+ generate_random_buffer(challenge->data,
sizeof(challenge->data));
+ }
+}
+
static NTSTATUS netlogon_creds_step_crypt(struct
netlogon_creds_CredentialState *creds,
const struct netr_Credential *in,
struct netr_Credential *out)
@@ -677,7 +705,7 @@ struct netlogon_creds_CredentialState
*netlogon_creds_server_init(TALLOC_CTX *me
struct netlogon_creds_CredentialState *creds = talloc_zero(mem_ctx,
struct netlogon_creds_CredentialState);
NTSTATUS status;
-
+ bool ok;
if (!creds) {
return NULL;
@@ -690,6 +718,20 @@ struct netlogon_creds_CredentialState
*netlogon_creds_server_init(TALLOC_CTX *me
dump_data_pw("Server chall", server_challenge->data,
sizeof(server_challenge->data));
dump_data_pw("Machine Pass", machine_password->hash,
sizeof(machine_password->hash));
+ ok = netlogon_creds_is_random_challenge(client_challenge);
+ if (!ok) {
+ DBG_WARNING("CVE-2020-1472(ZeroLogon): "
+ "non-random client challenge rejected for "
+ "client_account[%s] client_computer_name[%s]\n",
+ log_escape(mem_ctx, client_account),
+ log_escape(mem_ctx, client_computer_name));
+ dump_data(DBGLVL_WARNING,
+ client_challenge->data,
+ sizeof(client_challenge->data));
+ talloc_free(creds);
+ return NULL;
+ }
+
creds->computer_name = talloc_strdup(creds, client_computer_name);
if (!creds->computer_name) {
talloc_free(creds);
diff --git a/libcli/auth/netlogon_creds_cli.c b/libcli/auth/netlogon_creds_cli.c
index 407cb471cbc..12cb3149ff6 100644
--- a/libcli/auth/netlogon_creds_cli.c
+++ b/libcli/auth/netlogon_creds_cli.c
@@ -1177,8 +1177,7 @@ static void
netlogon_creds_cli_auth_challenge_start(struct tevent_req *req)
TALLOC_FREE(state->creds);
- generate_random_buffer(state->client_challenge.data,
- sizeof(state->client_challenge.data));
+ netlogon_creds_random_challenge(&state->client_challenge);
subreq = dcerpc_netr_ServerReqChallenge_send(state, state->ev,
state->binding_handle,
diff --git a/libcli/auth/proto.h b/libcli/auth/proto.h
index 88f4a7c6c50..a62668f088f 100644
--- a/libcli/auth/proto.h
+++ b/libcli/auth/proto.h
@@ -13,6 +13,9 @@
/* The following definitions come from
/home/jeremy/src/samba/git/master/source3/../source4/../libcli/auth/credentials.c
*/
+bool netlogon_creds_is_random_challenge(const struct netr_Credential
*challenge);
+void netlogon_creds_random_challenge(struct netr_Credential *challenge);
+
NTSTATUS netlogon_creds_des_encrypt_LMKey(struct
netlogon_creds_CredentialState *creds,
struct netr_LMSessionKey *key);
NTSTATUS netlogon_creds_des_decrypt_LMKey(struct
netlogon_creds_CredentialState *creds,
diff --git a/libcli/auth/wscript_build b/libcli/auth/wscript_build
index 41937623630..2a6a7468e45 100644
--- a/libcli/auth/wscript_build
+++ b/libcli/auth/wscript_build
@@ -18,7 +18,7 @@ bld.SAMBA_SUBSYSTEM('NTLM_CHECK',
bld.SAMBA_SUBSYSTEM('LIBCLI_AUTH',
source='credentials.c session.c smbencrypt.c smbdes.c',
- public_deps='MSRPC_PARSE gnutls GNUTLS_HELPERS',
+ public_deps='MSRPC_PARSE gnutls GNUTLS_HELPERS util_str_escape',
public_headers='credentials.h:domain_credentials.h'
)
diff --git a/source3/rpc_server/netlogon/srv_netlog_nt.c
b/source3/rpc_server/netlogon/srv_netlog_nt.c
index 2a2e2d0ac6e..c217fee9c43 100644
--- a/source3/rpc_server/netlogon/srv_netlog_nt.c
+++ b/source3/rpc_server/netlogon/srv_netlog_nt.c
@@ -48,6 +48,7 @@
#include "../lib/tsocket/tsocket.h"
#include "lib/param/param.h"
#include "libsmb/dsgetdcname.h"
+#include "lib/util/util_str_escape.h"
extern userdom_struct current_user_info;
@@ -841,8 +842,7 @@ NTSTATUS _netr_ServerReqChallenge(struct pipes_struct *p,
pipe_state->client_challenge = *r->in.credentials;
- generate_random_buffer(pipe_state->server_challenge.data,
- sizeof(pipe_state->server_challenge.data));
+ netlogon_creds_random_challenge(&pipe_state->server_challenge);
*r->out.return_credentials = pipe_state->server_challenge;
@@ -1074,20 +1074,25 @@ static NTSTATUS netr_creds_server_step_check(struct
pipes_struct *p,
{
NTSTATUS status;
bool schannel_global_required = (lp_server_schannel() == true) ?
true:false;
+ bool schannel_required = schannel_global_required;
+ const char *explicit_opt = NULL;
struct loadparm_context *lp_ctx;
+ struct netlogon_creds_CredentialState *creds = NULL;
+ enum dcerpc_AuthType auth_type = DCERPC_AUTH_TYPE_NONE;
+ uint16_t opnum = p->opnum;
+ const char *opname = "<unknown>";
+ static bool warned_global_once = false;
if (creds_out != NULL) {
*creds_out = NULL;
}
- if (schannel_global_required) {
- if (p->auth.auth_type != DCERPC_AUTH_TYPE_SCHANNEL) {
- DBG_ERR("[%s] is not using schannel\n",
- computer_name);
- return NT_STATUS_ACCESS_DENIED;
- }
+ if (opnum < ndr_table_netlogon.num_calls) {
+ opname = ndr_table_netlogon.calls[opnum].name;
}
+ auth_type = p->auth.auth_type;
+
lp_ctx = loadparm_init_s3(mem_ctx, loadparm_s3_helpers());
if (lp_ctx == NULL) {
DEBUG(0, ("loadparm_init_s3 failed\n"));
@@ -1096,9 +1101,97 @@ static NTSTATUS netr_creds_server_step_check(struct
pipes_struct *p,
status = schannel_check_creds_state(mem_ctx, lp_ctx,
computer_name,
received_authenticator,
- return_authenticator, creds_out);
+ return_authenticator, &creds);
talloc_unlink(mem_ctx, lp_ctx);
- return status;
+
+ if (!NT_STATUS_IS_OK(status)) {
+ ZERO_STRUCTP(return_authenticator);
+ return status;
+ }
+
+ /*
+ * We don't use lp_parm_bool(), as we
+ * need the explicit_opt pointer in order to
+ * adjust the debug messages.
+ */
+
+ explicit_opt = lp_parm_const_string(GLOBAL_SECTION_SNUM,
+ "server require schannel",
+ creds->account_name,
+ NULL);
+ if (explicit_opt != NULL) {
+ schannel_required = lp_bool(explicit_opt);
+ }
+
+ if (schannel_required) {
+ if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
+ *creds_out = creds;
+ return NT_STATUS_OK;
+ }
+
+ DBG_ERR("CVE-2020-1472(ZeroLogon): "
+ "%s request (opnum[%u]) without schannel from "
+ "client_account[%s] client_computer_name[%s]\n",
+ opname, opnum,
+ log_escape(mem_ctx, creds->account_name),
+ log_escape(mem_ctx, creds->computer_name));
+ DBG_ERR("CVE-2020-1472(ZeroLogon): Check if option "
+ "'server require schannel:%s = no' is needed! \n",
+ log_escape(mem_ctx, creds->account_name));
+ TALLOC_FREE(creds);
+ ZERO_STRUCTP(return_authenticator);
+ return NT_STATUS_ACCESS_DENIED;
+ }
+
+ if (!schannel_global_required && !warned_global_once) {
+ /*
+ * We want admins to notice their misconfiguration!
+ */
+ DBG_ERR("CVE-2020-1472(ZeroLogon): "
+ "Please configure 'server schannel = yes', "
+ "See
https://bugzilla.samba.org/show_bug.cgi?id=14497\n";);
+ warned_global_once = true;
+ }
+
+ if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
+ DBG_ERR("CVE-2020-1472(ZeroLogon): "
+ "%s request (opnum[%u]) WITH schannel from "
+ "client_account[%s] client_computer_name[%s]\n",
+ opname, opnum,
+ log_escape(mem_ctx, creds->account_name),
+ log_escape(mem_ctx, creds->computer_name));
+ DBG_ERR("CVE-2020-1472(ZeroLogon): "
+ "Option 'server require schannel:%s = no' not
needed!?\n",
+ log_escape(mem_ctx, creds->account_name));
+
+ *creds_out = creds;
+ return NT_STATUS_OK;
+ }
+
+ if (explicit_opt != NULL) {
+ DBG_INFO("CVE-2020-1472(ZeroLogon): "
+ "%s request (opnum[%u]) without schannel from "
+ "client_account[%s] client_computer_name[%s]\n",
+ opname, opnum,
+ log_escape(mem_ctx, creds->account_name),
+ log_escape(mem_ctx, creds->computer_name));
+ DBG_INFO("CVE-2020-1472(ZeroLogon): "
+ "Option 'server require schannel:%s = no' still
needed!\n",
+ log_escape(mem_ctx, creds->account_name));
+ } else {
+ DBG_ERR("CVE-2020-1472(ZeroLogon): "
+ "%s request (opnum[%u]) without schannel from "
+ "client_account[%s] client_computer_name[%s]\n",
+ opname, opnum,
+ log_escape(mem_ctx, creds->account_name),
+ log_escape(mem_ctx, creds->computer_name));
+ DBG_ERR("CVE-2020-1472(ZeroLogon): Check if option "
+ "'server require schannel:%s = no' might be needed!\n",
+ log_escape(mem_ctx, creds->account_name));
+ }
+
+ *creds_out = creds;
+ return NT_STATUS_OK;
}
@@ -1345,9 +1438,14 @@ NTSTATUS _netr_ServerPasswordSet2(struct pipes_struct *p,
{
NTSTATUS status;
struct netlogon_creds_CredentialState *creds = NULL;
- DATA_BLOB plaintext;
+ DATA_BLOB plaintext = data_blob_null;
+ DATA_BLOB new_password = data_blob_null;
+ size_t confounder_len;
+ DATA_BLOB dec_blob = data_blob_null;
+ DATA_BLOB enc_blob = data_blob_null;
struct samr_CryptPassword password_buf;
struct _samr_Credentials_t cr = { CRED_TYPE_PLAIN_TEXT, {0}};
+ bool ok;
become_root();
status = netr_creds_server_step_check(p, p->mem_ctx,
@@ -1387,21 +1485,103 @@ NTSTATUS _netr_ServerPasswordSet2(struct pipes_struct
*p,
516);
}
if (!NT_STATUS_IS_OK(status)) {
+ TALLOC_FREE(creds);
return status;
}
- if (!decode_pw_buffer(p->mem_ctx,
- password_buf.data,
- (char**) &plaintext.data,
- &plaintext.length,
- CH_UTF16)) {
+ if (!extract_pw_from_buffer(p->mem_ctx, password_buf.data,
&new_password)) {
DEBUG(2,("_netr_ServerPasswordSet2: unable to extract password "
"from a buffer. Rejecting auth request as a wrong
password\n"));
TALLOC_FREE(creds);
return NT_STATUS_WRONG_PASSWORD;
}
+ /*
+ * Make sure the length field was encrypted,
+ * otherwise we are under attack.
+ */
+ if (new_password.length == r->in.new_password->length) {
+ DBG_WARNING("Length[%zu] field not encrypted\n",
+ new_password.length);
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /*
+ * We don't allow empty passwords for machine accounts.
+ */
+ if (new_password.length < 2) {
+ DBG_WARNING("Empty password Length[%zu]\n",
+ new_password.length);
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /*
+ * Make sure the confounder part of CryptPassword
+ * buffer was encrypted, otherwise we are under attack.
+ */
+ confounder_len = 512 - new_password.length;
+ enc_blob = data_blob_const(r->in.new_password->data, confounder_len);
+ dec_blob = data_blob_const(password_buf.data, confounder_len);
+ if (data_blob_cmp(&dec_blob, &enc_blob) == 0) {
+ DBG_WARNING("Confounder buffer not encrypted Length[%zu]\n",
+ confounder_len);
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /*
+ * Check that the password part was actually encrypted,
+ * otherwise we are under attack.
+ */
+ enc_blob = data_blob_const(r->in.new_password->data + confounder_len,
+ new_password.length);
+ dec_blob = data_blob_const(password_buf.data + confounder_len,
+ new_password.length);
+ if (data_blob_cmp(&dec_blob, &enc_blob) == 0) {
+ DBG_WARNING("Password buffer not encrypted Length[%zu]\n",
+ new_password.length);
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /*
+ * don't allow zero buffers
+ */
+ if (all_zero(new_password.data, new_password.length)) {
+ DBG_WARNING("Password zero buffer Length[%zu]\n",
+ new_password.length);
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /* Convert from UTF16 -> plaintext. */
+ ok = convert_string_talloc(p->mem_ctx,
+ CH_UTF16,
+ CH_UNIX,
+ new_password.data,
+ new_password.length,
+ (void *)&plaintext.data,
+ &plaintext.length);
+ if (!ok) {
+ DBG_WARNING("unable to extract password from a buffer. "
+ "Rejecting auth request as a wrong password\n");
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
+ /*
+ * We don't allow empty passwords for machine accounts.
+ */
+
cr.creds.password = (const char*) plaintext.data;
+ if (strlen(cr.creds.password) == 0) {
+ DBG_WARNING("Empty plaintext password\n");
+ TALLOC_FREE(creds);
+ return NT_STATUS_WRONG_PASSWORD;
+ }
+
status = netr_set_machine_account_password(p->mem_ctx,
p->session_info,
p->msg_ctx,
diff --git a/source4/rpc_server/netlogon/dcerpc_netlogon.c
b/source4/rpc_server/netlogon/dcerpc_netlogon.c
index 0351e2d286c..0c5ed1f0665 100644
--- a/source4/rpc_server/netlogon/dcerpc_netlogon.c
+++ b/source4/rpc_server/netlogon/dcerpc_netlogon.c
@@ -92,8 +92,7 @@ static NTSTATUS dcesrv_netr_ServerReqChallenge(struct
dcesrv_call_state *dce_cal
pipe_state->client_challenge = *r->in.credentials;
- generate_random_buffer(pipe_state->server_challenge.data,
- sizeof(pipe_state->server_challenge.data));
+ netlogon_creds_random_challenge(&pipe_state->server_challenge);
*r->out.return_credentials = pipe_state->server_challenge;
@@ -627,26 +626,114 @@ static NTSTATUS
dcesrv_netr_creds_server_step_check(struct dcesrv_call_state *dc
NTSTATUS nt_status;
int schannel = lpcfg_server_schannel(dce_call->conn->dce_ctx->lp_ctx);
bool schannel_global_required = (schannel == true);
+ bool schannel_required = schannel_global_required;
--
Samba Shared Repository
