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CVE-2020-1472(ZeroLogon): s4:rpc_server/netlogon: log warnings about unsecure configurations

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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 <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>
This commit is contained in:
Stefan Metzmacher 2020-09-17 13:37:26 +02:00
parent f9b772bf28
commit ca8a0098ac
1 changed files with 63 additions and 3 deletions
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66
source4/rpc_server/netlogon/dcerpc_netlogon.c
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@ -627,10 +627,12 @@ static NTSTATUS dcesrv_netr_creds_server_step_check(struct dcesrv_call_state *dc
int schannel = lpcfg_server_schannel(dce_call->conn->dce_ctx->lp_ctx); int schannel = lpcfg_server_schannel(dce_call->conn->dce_ctx->lp_ctx);
bool schannel_global_required = (schannel == true); bool schannel_global_required = (schannel == true);
bool schannel_required = schannel_global_required; bool schannel_required = schannel_global_required;
const char *explicit_opt = NULL;
struct netlogon_creds_CredentialState *creds = NULL; struct netlogon_creds_CredentialState *creds = NULL;
enum dcerpc_AuthType auth_type = DCERPC_AUTH_TYPE_NONE; enum dcerpc_AuthType auth_type = DCERPC_AUTH_TYPE_NONE;
uint16_t opnum = dce_call->pkt.u.request.opnum; uint16_t opnum = dce_call->pkt.u.request.opnum;
const char *opname = "<unknown>"; const char *opname = "<unknown>";
static bool warned_global_once = false;
if (opnum < ndr_table_netlogon.num_calls) { if (opnum < ndr_table_netlogon.num_calls) {
opname = ndr_table_netlogon.calls[opnum].name; opname = ndr_table_netlogon.calls[opnum].name;
@ -649,11 +651,18 @@ static NTSTATUS dcesrv_netr_creds_server_step_check(struct dcesrv_call_state *dc
return nt_status; return nt_status;
} }
schannel_required = lpcfg_parm_bool(dce_call->conn->dce_ctx->lp_ctx, /*
* We don't use lpcfg_parm_bool(), as we
* need the explicit_opt pointer in order to
* adjust the debug messages.
*/
explicit_opt = lpcfg_get_parametric(dce_call->conn->dce_ctx->lp_ctx,
NULL, NULL,
"server require schannel", "server require schannel",
creds->account_name, creds->account_name);
schannel_global_required); if (explicit_opt != NULL) {
schannel_required = lp_bool(explicit_opt);
}
if (schannel_required) { if (schannel_required) {
if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) { if (auth_type == DCERPC_AUTH_TYPE_SCHANNEL) {
@ -667,11 +676,62 @@ static NTSTATUS dcesrv_netr_creds_server_step_check(struct dcesrv_call_state *dc
opname, opnum, opname, opnum,
log_escape(mem_ctx, creds->account_name), log_escape(mem_ctx, creds->account_name),
log_escape(mem_ctx, creds->computer_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); TALLOC_FREE(creds);
ZERO_STRUCTP(return_authenticator); ZERO_STRUCTP(return_authenticator);
return NT_STATUS_ACCESS_DENIED; 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; *creds_out = creds;
return NT_STATUS_OK; return NT_STATUS_OK;
} }