security: require POST+CSRF for GET-triggered purge/disable actions (GHSA-x664-x4hf-p9xh) (#8236)

* security: require POST+CSRF for GET-triggered purge/disable actions (GHSA-x664-x4hf-p9xh)

* style: align rrdcheck purge array operators for php-cs-fixer

automation_devices.php

@@ -65,6 +65,8 @@ set_default_action();
 
 switch(grv('action')) {
 	case 'purge':
+		csrf_require_post();
+
 		purge_discovery_results();
 
 		break;
@@ -611,6 +613,7 @@ function create_automation_devices_filter() : array {
 				'display'  => __('Purge'),
 				'action'   => 'default',
 				'title'    => __('Purge the Discovered Devices from the Database'),
+				'callback' => 'postUrl({ url: \'automation_devices.php?action=purge\' }, { __csrf_magic: csrfMagicToken })'
 			]
 		],
 		'sort' => [

changelog.d/GHSA-x664-x4hf-p9xh.security

@@ -0,0 +1 @@
+Require a POST request with a CSRF token for state-changing GET actions (User Log purge, Automation Devices purge, RRDCheck purge, and plugin disable) so they can no longer be triggered cross-site via a GET request

include/csrf.php

@@ -414,3 +414,20 @@ function csrf_error_callback() : void {
 
 	exit;
 }
+
+/**
+ * csrf_require_post - reject a non-POST request for a state-changing action.
+ *
+ * State-changing actions reached through a direct action= URL must arrive by
+ * POST so they cannot be triggered cross-site with a GET (for example an <img>
+ * tag).  csrf-magic validates the token on the resulting POST.
+ *
+ * @return void
+ */
+function csrf_require_post() : void {
+	if (!isset($_SERVER['REQUEST_METHOD']) || $_SERVER['REQUEST_METHOD'] !== 'POST') {
+		header('Allow: POST');
+		http_response_code(405);
+		exit;
+	}
+}

plugins.php

@@ -307,6 +307,8 @@ switch($action) {
 
 		break;
 	case 'disable':
+		csrf_require_post();
+
 		api_plugin_disable($plugin);
 
 		header('Location: plugins.php');
@@ -945,6 +947,18 @@ function update_show_current() : void {
 					displayDialog(url, dialogTitle, dialogMessage, dialogForm, buttonContinue, buttonCancel, 80, 400);
 				});
 
+				$('.pidisable').off('click').on('click', function(event) {
+					event.preventDefault();
+
+					var url = $(this).attr('href');
+
+					if (url == '' || url == '#') {
+						return;
+					}
+
+					postUrl({ url: url }, { __csrf_magic: csrfMagicToken });
+				});
+
 				$('.piforceremove').off('click').on('click', function(event) {
 					event.preventDefault();
 

rrdcheck.php

@@ -39,6 +39,8 @@ if (read_config_option('rrdcheck_enable') != 'on') {
 
 switch(grv('action')) {
 	case 'purge':
+		csrf_require_post();
+
 		rrdcheck_purge();
 
 	default:
@@ -254,6 +256,7 @@ function create_rrdcheck_filter() : array {
 				'display'  => __('Purge'),
 				'action'   => 'default',
 				'title'    => __('Purge Data Source Checks from the Database'),
+				'callback' => 'postUrl({ url: \'rrdcheck.php?action=purge\' }, { __csrf_magic: csrfMagicToken })'
 			]
 		],
 		'sort' => [

user_log.php

@@ -29,6 +29,8 @@ set_default_action();
 
 switch (grv('action')) {
 	case 'purge_execute':
+		csrf_require_post();
+
 		clear_user_log();
 		raise_message('purge_user_log', __('User Log Purged.'), MESSAGE_LEVEL_INFO);
 		header('location: user_log.php');
@@ -220,7 +222,7 @@ function purge_user_log() : void {
 				$(function() {
 					$('#pc').click(function() {
 						strURL = location.pathname+'?action=purge_execute';
-						loadUrl({url:strURL})
+						postUrl({url: strURL}, {__csrf_magic: csrfMagicToken});
 					});
 
 					$('#cancel').click(function() {