一.Brute Force

中等难度无法使用sql注入，所以直接用Burp进行爆破

二.Command Injection

先看代码

<?php

if( isset( $_POST[ 'Submit' ]  ) ) {
    // Get input
    $target = $_REQUEST[ 'ip' ];

    // Set blacklist
    $substitutions = array(
        '&&' => '',
        ';'  => '',
    );

    // Remove any of the charactars in the array (blacklist).
    $target = str_replace( array_keys( $substitutions ), $substitutions, $target );

    // Determine OS and execute the ping command.
    if( stristr( php_uname( 's' ), 'Windows NT' ) ) {
        // Windows
        $cmd = shell_exec( 'ping  ' . $target );
    }
    else {
        // *nix
        $cmd = shell_exec( 'ping  -c 4 ' . $target );
    }

    // Feedback for the end user
    echo "<pre>{$cmd}</pre>";
}

?>   

可以看到该题对’&&‘和’;'进行了过滤，所以使用其他拼接符注入
例如：127.0.0.1 | whoami

三.CSRF

先看看代码

<?php

if( isset( $_GET[ 'Change' ] ) ) {
    // Checks to see where the request came from
    if( eregi( $_SERVER[ 'SERVER_NAME' ], $_SERVER[ 'HTTP_REFERER' ] ) ) {
        // Get input
        $pass_new  = $_GET[ 'password_new' ];
        $pass_conf = $_GET[ 'password_conf' ];

        // Do the passwords match?
        if( $pass_new == $pass_conf ) {
            // They do!
            $pass_new = mysql_real_escape_string( $pass_new );
            $pass_new = md5( $pass_new );

            // Update the database
            $insert = "UPDATE `users` SET password = '$pass_new' WHERE user = '" . dvwaCurrentUser() . "';";
            $result = mysql_query( $insert ) or die( '<pre>' . mysql_error() . '</pre>' );

            // Feedback for the user
            echo "<pre>Password Changed.</pre>";
        }
        else {
            // Issue with passwords matching
            echo "<pre>Passwords did not match.</pre>";
        }
    }
    else {
        // Didn't come from a trusted source
        echo "<pre>That request didn't look correct.</pre>";
    }

    mysql_close();
}

?> 

可以看到要求检查HTTP_REFERER中是否包含SERVER_NAME（http包头的Host参数，及要访问的主机名。）
​ 把网页文件名改为“访问主机名.html”即可绕过

四.File Inclusion

先看一手代码

<?php

// The page we wish to display
$file = $_GET[ 'page' ];

// Input validation
$file = str_replace( array( "http://", "https://" ), "", $file );
$file = str_replace( array( "../", "..\"" ), "", $file );

?>

可以发现这次服务器过滤了http://,https://,…/,…\

但是str_replace()函数可以使用双写来跳过防护措施

注：过滤措施对使用绝对路径方式进行文件包含无效。