【DVWA】Brute Force(暴力破解)通關教程

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日期：2019-08-01 14:49:47
更新：
作者：Bay0net
介紹：一直以為爆破很簡單，直到學習了 Burp 的宏錄制和匹配關鍵詞，才發現 burp 能這么玩。。。

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0x01、 漏洞介紹

利用大量的用戶名和字典，去對賬號進行暴力破解，人的問題（弱密碼）可能是永遠都無法防御的一個點吧。

DVWA 沒模擬驗證碼缺陷的相關漏洞，在實戰中，會遇到很多驗證碼無效的栗子。

0x02、Low Security Level

查看源碼

<?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();
}

?> 

分析源碼

接受 username 和 password 的值，然后傳入數據庫做比較，直接使用爆破即可。

萬能密碼

此處也可以使用萬能密碼進行登錄。

admin'or '1'='1
admin' -- -
admin' # 

0x03、Medium Security Level

查看源碼

<?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();
}

?> 

分析源碼

1、對傳過來的值，使用了 mysql_real_escape_string() 函數，轉義了以下字符：

\x00
\n
\r
\
'
"
\x1a

2、使用了 sleep(2) 函數，如果密碼錯誤，則延時兩秒響應。

如果爆破的話，還是可以直接進行爆破的，只不過速度慢了些而已。。

萬能密碼

因為過濾了單引號，我們無法閉合掉前面的單引號，所以此處無法再使用萬能密碼了。

0x04、High Security Level

查看源碼

<?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();

?> 

分析源碼

可以發現，每次發送的時候，都帶上了一個 user_token，每次發送請求的時候 user_token 都是會變的，而 user_token 是來自於上一個數據包的。



使用 burp 爆破

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

選擇新建宏


添加的時候，選擇配置



爆破成功。。挺費勁的，不如直接寫 python 腳本。。



發現了一個問題，密碼為 b 的 user_token，並不是密碼 a 響應報文里面的 user_token，推測原理如下：

每次 burp 都會去訪問之前宏里面的頁面，然后獲取 user_token，再給爆破數據包里面的 user_token 替換上，所以流程不是 a -> b -> c，而是 get_user_token -> a -> get_user_token -> b .....

0x05、Impossible Security Level

查看源碼

<?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();

?> 

重點在於：

$total_failed_login = 3;
$lockout_time       = 15;
$account_locked     = false;

錯誤 3 次的話，就鎖定 15 分鍾，如果在實戰中遇到這種情況，可以采用爆破用戶名的方法來做。

0x06、burp 爆破匹配關鍵詞

設置如下：


爆破成功會這樣顯示：