CVE-2013-4881: Cross-Site Request Forgery (CSRF) (CWE-352)
value: Cross-site request forgery (CSRF) vulnerability in core/admin/modules/users/create.php in BigTree CMS 4.0 RC2 and earlier allows remote attackers to hijack the authentication of administrators for requests that create an administrative user via an add user action to index.php.
CWE description: The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.
Published: 2013-08-19T13:07Z
Repository: https://github.com/bigtreecms/BigTree-CMS
Language: PHP
Files changed: core/admin/modules/users/create.php, core/admin/modules/users/update.php
Commit date: 2013-07-17 11:19:11 -0400
Commit message: Fixed a Cross-Site Request Forgery exploit that would allow logged-in BigTree admins hitting a malicious page to automatically create / update users.

Diff: diff --git a/core/admin/modules/users/create.php b/core/admin/modules/users/create.php
index f6dd3e26..be26643a 100755
--- a/core/admin/modules/users/create.php
+++ b/core/admin/modules/users/create.php
@@ -1,13 +1,23 @@
 <?
-	$admin->requireLevel(1);
-	$id = $admin->createUser($_POST);	
+	if ($_SERVER["HTTP_REFERER"] != ADMIN_ROOT."users/add/") {
+?>
+<div class="container">
+	<section>
+		<p>To create a user, please access the <a href="<?=ADMIN_ROOT?>users/add/">Add User</a> page.</p>
+	</section>
+</div>
+<?
+	} else {
+		$admin->requireLevel(1);
+		$id = $admin->createUser($_POST);	
+		
+		if (!$id) {
+			$_SESSION["bigtree_admin"]["create_user"] = $_POST;
+			$admin->growl("Users","Creation Failed","error");
+			BigTree::redirect(ADMIN_ROOT."users/add/");
+		}
 	
-	if (!$id) {
-		$_SESSION["bigtree_admin"]["create_user"] = $_POST;
-		$admin->growl("Users","Creation Failed","error");
-		BigTree::redirect(ADMIN_ROOT."users/add/");
+		$admin->growl("Users","Added User");
+		BigTree::redirect(ADMIN_ROOT."users/edit/$id/");
 	}
-
-	$admin->growl("Users","Added User");
-	BigTree::redirect(ADMIN_ROOT."users/edit/$id/");
 ?>
\ No newline at end of file
diff --git a/core/admin/modules/users/update.php b/core/admin/modules/users/update.php
index 266bb7ec..8896dfd5 100755
--- a/core/admin/modules/users/update.php
+++ b/core/admin/modules/users/update.php
@@ -1,16 +1,26 @@
 <?
-	$perms = json_decode($_POST["permissions"],true);
-	$_POST["permissions"] = array("page" => $perms["Page"],"module" => $perms["Module"],"resources" => $perms["Resource"],"module_gbp" => $perms["ModuleGBP"]);
-	$_POST["alerts"] = json_decode($_POST["alerts"],true);
-	$success = $admin->updateUser($_POST["id"],$_POST);
-	
-	if (!$success) {
-		$_SESSION["bigtree_admin"]["update_user"] = $_POST;
-		$admin->growl("Users","Update Failed","error");
-		BigTree::redirect(ADMIN_ROOT."users/edit/".end($bigtree["path"])."/");
+	if ($_SERVER["HTTP_REFERER"] != ADMIN_ROOT."users/edit/".$_POST["id"]."/") {
+?>
+<div class="container">
+	<section>
+		<p>To update a user, please access the <a href="<?=ADMIN_ROOT?>users/edit/<?=$_POST["id"]?>/">Edit User</a> page.</p>
+	</section>
+</div>
+<?
+	} else {
+		$perms = json_decode($_POST["permissions"],true);
+		$_POST["permissions"] = array("page" => $perms["Page"],"module" => $perms["Module"],"resources" => $perms["Resource"],"module_gbp" => $perms["ModuleGBP"]);
+		$_POST["alerts"] = json_decode($_POST["alerts"],true);
+		$success = $admin->updateUser($_POST["id"],$_POST);
+		
+		if (!$success) {
+			$_SESSION["bigtree_admin"]["update_user"] = $_POST;
+			$admin->growl("Users","Update Failed","error");
+			BigTree::redirect(ADMIN_ROOT."users/edit/".end($bigtree["path"])."/");
+		}
+		
+		$admin->growl("Users","Updated User");
+		
+		BigTree::redirect(ADMIN_ROOT."users/");
 	}
-	
-	$admin->growl("Users","Updated User");
-	
-	BigTree::redirect(ADMIN_ROOT."users/");
 ?>
\ No newline at end of file

Vulnerable code: 	$admin->requireLevel(1);
	$id = $admin->createUser($_POST);	
	if (!$id) {
		$_SESSION["bigtree_admin"]["create_user"] = $_POST;
		$admin->growl("Users","Creation Failed","error");
		BigTree::redirect(ADMIN_ROOT."users/add/");

	$admin->growl("Users","Added User");
	BigTree::redirect(ADMIN_ROOT."users/edit/$id/");
	$perms = json_decode($_POST["permissions"],true);
	$_POST["permissions"] = array("page" => $perms["Page"],"module" => $perms["Module"],"resources" => $perms["Resource"],"module_gbp" => $perms["ModuleGBP"]);
	$_POST["alerts"] = json_decode($_POST["alerts"],true);
	$success = $admin->updateUser($_POST["id"],$_POST);
	
	if (!$success) {
		$_SESSION["bigtree_admin"]["update_user"] = $_POST;
		$admin->growl("Users","Update Failed","error");
		BigTree::redirect(ADMIN_ROOT."users/edit/".end($bigtree["path"])."/");
	
	$admin->growl("Users","Updated User");
	
	BigTree::redirect(ADMIN_ROOT."users/");
Fixed code: 	if ($_SERVER["HTTP_REFERER"] != ADMIN_ROOT."users/add/") {
?>
<div class="container">
	<section>
		<p>To create a user, please access the <a href="<?=ADMIN_ROOT?>users/add/">Add User</a> page.</p>
	</section>
</div>
<?
	} else {
		$admin->requireLevel(1);
		$id = $admin->createUser($_POST);	
		
		if (!$id) {
			$_SESSION["bigtree_admin"]["create_user"] = $_POST;
			$admin->growl("Users","Creation Failed","error");
			BigTree::redirect(ADMIN_ROOT."users/add/");
		}
		$admin->growl("Users","Added User");
		BigTree::redirect(ADMIN_ROOT."users/edit/$id/");
	if ($_SERVER["HTTP_REFERER"] != ADMIN_ROOT."users/edit/".$_POST["id"]."/") {
?>
<div class="container">
	<section>
		<p>To update a user, please access the <a href="<?=ADMIN_ROOT?>users/edit/<?=$_POST["id"]?>/">Edit User</a> page.</p>
	</section>
</div>
<?
	} else {
		$perms = json_decode($_POST["permissions"],true);
		$_POST["permissions"] = array("page" => $perms["Page"],"module" => $perms["Module"],"resources" => $perms["Resource"],"module_gbp" => $perms["ModuleGBP"]);
		$_POST["alerts"] = json_decode($_POST["alerts"],true);
		$success = $admin->updateUser($_POST["id"],$_POST);
		
		if (!$success) {
			$_SESSION["bigtree_admin"]["update_user"] = $_POST;
			$admin->growl("Users","Update Failed","error");
			BigTree::redirect(ADMIN_ROOT."users/edit/".end($bigtree["path"])."/");
		}
		
		$admin->growl("Users","Updated User");
		
		BigTree::redirect(ADMIN_ROOT."users/");