CVE-2013-4881 (PHP, published 2013-08-19T13:07Z)
Description: 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.
Severity: MEDIUM (CVSS v3 base score: )
Weakness: CWE-352 \u2014 Cross-Site Request Forgery (CSRF)
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.
Repository: https://github.com/bigtreecms/BigTree-CMS
Files changed:
core/admin/modules/users/create.php
core/admin/modules/users/update.php
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.


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/");