SchoolCMS version 2.3.1 allows file upload via the theme upload feature at admin.php?m=admin&c=theme&a=upload by using the .zip extension along with the _Static substring, changing the Content-Type to application/zip, and placing PHP code after the ZIP header. This ultimately allows execution of arbitrary PHP code in Public\Home\1_Static.php because of mishandling in the Application\Admin\Controller\ThemeController.class.php Upload() function.