From: Stefan Metzmacher <metze@samba.org>
Date: Wed, 16 Sep 2020 14:04:57 +0000 (+0200)
Subject: CVE-2020-1472(ZeroLogon): libcli/auth: add netlogon_creds_random_challenge()
X-Git-Tag: samba-4.10.18~19
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3e816443470860a93793117b26328d2ebaa36a6;p=thirdparty%2Fsamba.git

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 <metze@samba.org>
---

diff --git a/libcli/auth/credentials.c b/libcli/auth/credentials.c
index b6c8ba281ba..dbbef9e7a3c 100644
--- a/libcli/auth/credentials.c
+++ b/libcli/auth/credentials.c
@@ -26,9 +26,17 @@
 #include "libcli/auth/libcli_auth.h"
 #include "../libcli/security/dom_sid.h"
 
+
+void netlogon_creds_random_challenge(struct netr_Credential *challenge)
+{
+	ZERO_STRUCTP(challenge);
+	generate_random_buffer(challenge->data, sizeof(challenge->data));
+}
+
 static void netlogon_creds_step_crypt(struct netlogon_creds_CredentialState *creds,
 				      const struct netr_Credential *in,
 				      struct netr_Credential *out)
+
 {
 	if (creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) {
 		AES_KEY key;
diff --git a/libcli/auth/proto.h b/libcli/auth/proto.h
index 82febe74440..82797d453ed 100644
--- a/libcli/auth/proto.h
+++ b/libcli/auth/proto.h
@@ -11,6 +11,8 @@
 
 /* The following definitions come from /home/jeremy/src/samba/git/master/source3/../source4/../libcli/auth/credentials.c  */
 
+void netlogon_creds_random_challenge(struct netr_Credential *challenge);
+
 void netlogon_creds_des_encrypt_LMKey(struct netlogon_creds_CredentialState *creds, struct netr_LMSessionKey *key);
 void netlogon_creds_des_decrypt_LMKey(struct netlogon_creds_CredentialState *creds, struct netr_LMSessionKey *key);
 void netlogon_creds_des_encrypt(struct netlogon_creds_CredentialState *creds, struct samr_Password *pass);