Zploit 0-Day Shell

:: Editing File: send_otp.php

<?php 
session_start();
include('db.php');
$mobile_no = $_POST['mobile_no'];
$email = $_POST['email'];
$otp = rand(100000, 999999);
$sql_chk_mobile = "SELECT * FROM user_details WHERE mobile = '$mobile_no'";
$result_chk_mobile = mysqli_query($conn, $sql_chk_mobile);
if (mysqli_num_rows($result_chk_mobile) > 0) {
	echo "4"; //mobile already register
}
else{
	$sql_chk_email = "SELECT * FROM user_details WHERE email = '$email'";
	$result_chk_email = mysqli_query($conn, $sql_chk_email);
	if (mysqli_num_rows($result_chk_email) > 0) {
		echo "3"; //email already register
	}
	else{

$fields = array(
    "sender_id" => "DMSCLG",
    "message" => "159475",
    "variables_values" => $otp,
    "route" => "dlt",
    "numbers" => $mobile_no,
    );

$curl = curl_init();

curl_setopt_array($curl, array(
	  CURLOPT_URL => "https://www.fast2sms.com/dev/bulkV2",
	  CURLOPT_RETURNTRANSFER => true,
	  CURLOPT_ENCODING => "",
	  CURLOPT_MAXREDIRS => 10,
	  CURLOPT_TIMEOUT => 30,
	  CURLOPT_SSL_VERIFYHOST => 0,
	  CURLOPT_SSL_VERIFYPEER => 0,
	  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
	  CURLOPT_CUSTOMREQUEST => "POST",
	  CURLOPT_POSTFIELDS => json_encode($fields),
	  CURLOPT_HTTPHEADER => array(
	    "authorization: enMHh29XWRsEAT3km1iwtDl8YyF5b0gcSLx7p4qIP6odBjzCOraYMyRohu7BNKvmZbS8jqdL59kcg4zl",
	    "accept: */*",
	    "cache-control: no-cache",
	    "content-type: application/json"
	  ),
	));

$response = curl_exec($curl);
	$err = curl_error($curl);

curl_close($curl);

$_SESSION['otp'] = $otp;
		echo "1";
	}
}
?>