SQL注入：Sql注入中时间函数的应用

时间窃取相关函数

休眠函数sleep()

mysql> select sleep(1);
+----------+
| sleep(1) |
+----------+
|        0 |
+----------+
1 row in set (1.00 sec)

压力测试函数

#计算10000000次
mysql> select benchmark(10000000,md5('xxxxxxxxxx'));
+----------------------------------------+
| benchmark(10000000,md5('xxxxxxxxxx')) |
+----------------------------------------+
|                                      0 |
+----------------------------------------+
1 row in set (3.51 sec)

if函数

mysql> select if(5>2,'a','b');
+-----------------+
| if(5>2,'a','b') |
+-----------------+
| a               |
+-----------------+

具体应用

#例子
select * from str and if(left(version(),1)>1,sleep(1),1);

#例子
mysql> select if(left(version(),1)>1,sleep(1),1);
+------------------------------------+
| if(left(version(),1)>1,sleep(1),1) |
+------------------------------------+
|                                  0 |
+------------------------------------+
1 row in set (1.00 sec)

原理：根据网页显示是否够存在延迟，来判断当前猜测的字符是否正常