【DVWA】Brute Force(暴力破解)通关教程

日期：2019-08-01 14:49:47
更新：
作者：Bay0net
介绍：一直以为爆破很简单，直到学习了 Burp 的宏录制和匹配关键词，才发现 burp 能这么玩。。。

0x01、漏洞介绍

利用大量的用户名和字典，去对账号进行暴力破解，人的问题（弱密码）可能是永远都无法防御的一个点吧。

DVWA 没模拟验证码缺陷的相关漏洞，在实战中，会遇到很多验证码无效的栗子。

0x02、Low Security Level

查看源码

<?php

if( isset( $_GET[ 'Login' ] ) ) {

    // Get username

    $user = $_GET[ 'username' ];

    // Get password

    $pass = $_GET[ 'password' ];

    $pass = md5( $pass );

    // Check the database

    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";

    $result = mysql_query( $query ) or die( '<pre>' . mysql_error() . '</pre>' );

    if( $result && mysql_num_rows( $result ) == 1 ) {

        // Get users details

        $avatar = mysql_result( $result, 0, "avatar" );

        // Login successful

        echo "<p>Welcome to the password protected area {$user}</p>";

        echo "<img src=\"{$avatar}\" />";

    }

    else {

        // Login failed

        echo "<pre><br />Username and/or password incorrect.</pre>";

    }

    mysql_close();

}

?>

分析源码

接受 username 和 password 的值，然后传入数据库做比较，直接使用爆破即可。

万能密码

此处也可以使用万能密码进行登录。

admin'or '1'='1

admin' -- -

admin' #

0x03、Medium Security Level

查看源码

<?php

if( isset( $_GET[ 'Login' ] ) ) {

    // Sanitise username input

    $user = $_GET[ 'username' ];

    $user = mysql_real_escape_string( $user );

    // Sanitise password input

    $pass = $_GET[ 'password' ];

    $pass = mysql_real_escape_string( $pass );

    $pass = md5( $pass );

    // Check the database

    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";

    $result = mysql_query( $query ) or die( '<pre>' . mysql_error() . '</pre>' );

    if( $result && mysql_num_rows( $result ) == 1 ) {

        // Get users details

        $avatar = mysql_result( $result, 0, "avatar" );

        // Login successful

        echo "<p>Welcome to the password protected area {$user}</p>";

        echo "<img src=\"{$avatar}\" />";

    }

    else {

        // Login failed

        sleep( 2 );

        echo "<pre><br />Username and/or password incorrect.</pre>";

    }

    mysql_close();

}

?>

分析源码

1、对传过来的值，使用了 mysql_real_escape_string() 函数，转义了以下字符：

\x00

\n

\r

\

'

"

\x1a

2、使用了 sleep(2) 函数，如果密码错误，则延时两秒响应。

如果爆破的话，还是可以直接进行爆破的，只不过速度慢了些而已。。

万能密码

因为过滤了单引号，我们无法闭合掉前面的单引号，所以此处无法再使用万能密码了。

0x04、High Security Level

查看源码

<?php

if( isset( $_GET[ 'Login' ] ) ) {

    // Check Anti-CSRF token

    checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

    // Sanitise username input

    $user = $_GET[ 'username' ];

    $user = stripslashes( $user );

    $user = mysql_real_escape_string( $user );

    // Sanitise password input

    $pass = $_GET[ 'password' ];

    $pass = stripslashes( $pass );

    $pass = mysql_real_escape_string( $pass );

    $pass = md5( $pass );

    // Check database

    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";

    $result = mysql_query( $query ) or die( '<pre>' . mysql_error() . '</pre>' );

    if( $result && mysql_num_rows( $result ) == 1 ) {

        // Get users details

        $avatar = mysql_result( $result, 0, "avatar" );

        // Login successful

        echo "<p>Welcome to the password protected area {$user}</p>";

        echo "<img src=\"{$avatar}\" />";

    }

    else {

        // Login failed

        sleep( rand( 0, 3 ) );

        echo "<pre><br />Username and/or password incorrect.</pre>";

    }

    mysql_close();

}

// Generate Anti-CSRF token

generateSessionToken();

?>

分析源码

可以发现，每次发送的时候，都带上了一个 user_token，每次发送请求的时候 user_token 都是会变的，而 user_token 是来自于上一个数据包的。

使用 burp 爆破

依次选择【Project options】->【Sessions】->【add】-> 【add a Rule Description】-> 【Run a macro(宏)】

选择新建宏

添加的时候，选择配置

爆破成功。。挺费劲的，不如直接写 python 脚本。。

发现了一个问题，密码为 b 的 user_token，并不是密码 a 响应报文里面的 user_token，推测原理如下：

每次 burp 都会去访问之前宏里面的页面，然后获取 user_token，再给爆破数据包里面的 user_token 替换上，所以流程不是 a -> b -> c，而是 get_user_token -> a -> get_user_token -> b .....

0x05、Impossible Security Level

查看源码

<?php

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

    // Check Anti-CSRF token

    checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

    // Sanitise username input

    $user = $_POST[ 'username' ];

    $user = stripslashes( $user );

    $user = mysql_real_escape_string( $user );

    // Sanitise password input

    $pass = $_POST[ 'password' ];

    $pass = stripslashes( $pass );

    $pass = mysql_real_escape_string( $pass );

    $pass = md5( $pass );

    // Default values

    $total_failed_login = 3;

    $lockout_time       = 15;

    $account_locked     = false;

    // Check the database (Check user information)

    $data = $db->prepare( 'SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;' );

    $data->bindParam( ':user', $user, PDO::PARAM_STR );

    $data->execute();

    $row = $data->fetch();

    // Check to see if the user has been locked out.

    if( ( $data->rowCount() == 1 ) && ( $row[ 'failed_login' ] >= $total_failed_login ) )  {

        // User locked out.  Note, using this method would allow for user enumeration!

        //echo "<pre><br />This account has been locked due to too many incorrect logins.</pre>";

        // Calculate when the user would be allowed to login again

        $last_login = $row[ 'last_login' ];

        $last_login = strtotime( $last_login );

        $timeout    = strtotime( "{$last_login} +{$lockout_time} minutes" );

        $timenow    = strtotime( "now" );

        // Check to see if enough time has passed, if it hasn't locked the account

        if( $timenow > $timeout )

            $account_locked = true;

    }

    // Check the database (if username matches the password)

    $data = $db->prepare( 'SELECT * FROM users WHERE user = (:user) AND password = (:password) LIMIT 1;' );

    $data->bindParam( ':user', $user, PDO::PARAM_STR);

    $data->bindParam( ':password', $pass, PDO::PARAM_STR );

    $data->execute();

    $row = $data->fetch();

    // If its a valid login...

    if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) {

        // Get users details

        $avatar       = $row[ 'avatar' ];

        $failed_login = $row[ 'failed_login' ];

        $last_login   = $row[ 'last_login' ];

        // Login successful

        echo "<p>Welcome to the password protected area <em>{$user}</em></p>";

        echo "<img src=\"{$avatar}\" />";

        // Had the account been locked out since last login?

        if( $failed_login >= $total_failed_login ) {

            echo "<p><em>Warning</em>: Someone might of been brute forcing your account.</p>";

            echo "<p>Number of login attempts: <em>{$failed_login}</em>.<br />Last login attempt was at: <em>${last_login}</em>.</p>";

        }

        // Reset bad login count

        $data = $db->prepare( 'UPDATE users SET failed_login = "0" WHERE user = (:user) LIMIT 1;' );

        $data->bindParam( ':user', $user, PDO::PARAM_STR );

        $data->execute();

    }

    else {

        // Login failed

        sleep( rand( 2, 4 ) );

        // Give the user some feedback

        echo "<pre><br />Username and/or password incorrect.<br /><br/>Alternative, the account has been locked because of too many failed logins.<br />If this is the case, <em>please try again in {$lockout_time} minutes</em>.</pre>";

        // Update bad login count

        $data = $db->prepare( 'UPDATE users SET failed_login = (failed_login + 1) WHERE user = (:user) LIMIT 1;' );

        $data->bindParam( ':user', $user, PDO::PARAM_STR );

        $data->execute();

    }

    // Set the last login time

    $data = $db->prepare( 'UPDATE users SET last_login = now() WHERE user = (:user) LIMIT 1;' );

    $data->bindParam( ':user', $user, PDO::PARAM_STR );

    $data->execute();

}

// Generate Anti-CSRF token

generateSessionToken();

?>

重点在于：

$total_failed_login = 3;

$lockout_time       = 15;

$account_locked     = false;

错误 3 次的话，就锁定 15 分钟，如果在实战中遇到这种情况，可以采用爆破用户名的方法来做。

0x06、burp 爆破匹配关键词

设置如下：

爆破成功会这样显示：