DVWA 靶场（一）暴力破解

前言

Brute Force(暴力破解)，就是指黑客利用黑客字典，通过穷举法猜测用户口令。

Low

源码分析

<?php
//检查变量是否设置（先看有没有Login参数）
if( isset( $_GET[ 'Login' ] ) ) {
    //获取用户
    $user = $_GET[ 'username' ];
    //获取密码
    $pass = $_GET[ 'password' ];
    //将密码使用md5加密
    $pass = md5( $pass );
    //构建SQL语句，查询结果保存在query变量中
    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
    //数据库查询，将查询结果保存在result变量中，查到了，保存用户具体信息；未查到，就在页面上输入错误结果，result为空
    $result = mysqli_query($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>' );
    //结果存在并且返回一条记录，说明查到了
    if( $result && mysqli_num_rows( $result ) == 1 ) {
    //查询结果关联数据row，row已经变成键值对
        $row    = mysqli_fetch_assoc( $result );
    //获取登录成功图片
        $avatar = $row["avatar"];
        // Login successful
        //登录成功，输出到页面上
        echo "<p>Welcome to the password protected area {$user}</p>";
        echo "<img src=\"{$avatar}\" />";
    }
    else {
        // Login failed
    //未查到，错误信息输出到页面上
        echo "<pre><br />Username and/or password incorrect.</pre>";
    }
    //释放资源
    ((is_null($___mysqli_res = mysqli_close($GLOBALS["___mysqli_ston"]))) ? false : $___mysqli_res);
}

?>

手动检测

我们先尝试随便输一个账号密码
靶场会直接返回明文账号密码在URL上

使用大佬的万能密码语句

admin' or '1'='1

然后我们发现这里存在SQL注入漏洞

既然如此~
我们直接上工具爆破吧

BurpSuite

抓取数据包

Proxy（代理） --> Intercept（拦截） --> 发送到 Intruder

自动化枚举

1. 清除全文 Payload 位置
2. 为需要测试字段添加 Payload 位置

3. 为 Payload 添加 Password 字典

4. 点击 开始攻击 稍等片刻

5. 输入爆破出来的账号密码

Medium

源码分析

通过和Low源码比较
我们不难发现Medium源码中
加入了 mysqli_real_escape_string() 函数
该函数可过滤部分特殊符号进而抵御由此引起的SQL Injection

<?php
//是否存在Login变量（标签里面的name），检查是否存在Login按钮
if( isset( $_GET[ 'Login' ] ) ) {
    // Sanitise username input
    //获取用户名，存入user变量里
    $user = $_GET[ 'username' ];
    //user中x00，n，r，，’，”，x1a转义，防SQL注入
    $user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));

    // Sanitise password input
    $pass = $_GET[ 'password' ];
    //pass中x00，n，r，，’，”，x1a转义，防SQL注入
    $pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
    //密码加密
    $pass = md5( $pass );

    // Check the database
    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
    $result = mysqli_query($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>' );

    if( $result && mysqli_num_rows( $result ) == 1 ) {
        // Get users details
        $row    = mysqli_fetch_assoc( $result );
        $avatar = $row["avatar"];

        // Login successful
        echo "<p>Welcome to the password protected area {$user}</p>";
        echo "<img src=\"{$avatar}\" />";
    }
    else {
        // Login failed，失败后会延时2s
        sleep( 2 );
        echo "<pre><br />Username and/or password incorrect.</pre>";
    }

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

?>

手动检测

我们再来试一试万能语句
这次SQL注入就已经被拦截掉了

BurpSuite

抓取数据包

Proxy（代理） --> Intercept（拦截） --> 发送到 Intruder

自动化枚举

因为Medium没有从代码层面防止爆破行为
所以还是直接使用Low方法进行爆破即可

1. 清除全文 Payload 位置
2. 为需要测试字段添加 Payload 位置

3. 为 Payload 添加 Password 字典

4. 点击 开始攻击 稍等片刻

5. 输入爆破出来的账号密码

High

源码分析

通过对High源码的分析
不难发现加入了Token机制
每次登录请求时都会生成新的Token

<?php

if( isset( $_POST[ 'Login' ] ) && isset ($_POST['username']) && isset ($_POST['password']) ) {
    // Check Anti-CSRF token
    checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

    // Sanitise username input
    $user = $_POST[ 'username' ];
    $user = stripslashes( $user );
    $user = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $user ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));

    // Sanitise password input
    $pass = $_POST[ 'password' ];
    $pass = stripslashes( $pass );
    $pass = ((isset($GLOBALS["___mysqli_ston"]) && is_object($GLOBALS["___mysqli_ston"])) ? mysqli_real_escape_string($GLOBALS["___mysqli_ston"],  $pass ) : ((trigger_error("[MySQLConverterToo] Fix the mysql_escape_string() call! This code does not work.", E_USER_ERROR)) ? "" : ""));
    $pass = md5( $pass );

    // Default values
    $total_failed_login = 3;
    $lockout_time       = 15;
    $account_locked     = false;

    // Check the database (Check user information)
    //如果在锁定状态就输出已被锁定
    $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
        //计算用户能再次登录的时间
        $last_login = strtotime( $row[ 'last_login' ] );
        $timeout    = $last_login + ($lockout_time * 60);
        $timenow    = time();

        /*
        print "The last login was: " . date ("h:i:s", $last_login) . "<br />";
        print "The timenow is: " . date ("h:i:s", $timenow) . "<br />";
        print "The timeout is: " . date ("h:i:s", $timeout) . "<br />";
        */

        // Check to see if enough time has passed, if it hasn't locked the account
        if( $timenow < $timeout ) {
            $account_locked = true;
            // print "The account is locked<br />";
        }
    }

    // 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();

?>

BurpSuite

抓取数据包

Proxy（代理） --> Intercept（拦截） --> 发送到 Intruder

自动化枚举

1. 清除全文 Payload 位置
2. 为需要测试字段添加 Payload 位置

3. 多字段枚举需要修改攻击类型

4. 为 Payload(Password) 添加 Password 字典

5. 资源池（Resource Pool） 设置爆破最大并发线程设置为1

6. 设置（Options） --> 检索 - 提取（Grep - Extract） --> 添加

7. 获取响应（Fetch response） --> 选择 Token

8. 重定向（Redirections） 选择 总是（Always）

9. 为 Payload(Token) 使用 递归提取（Recursive grep） 并填写之前获取到的 Token

10. 然后我们开始攻击

参考 & 引用

https://zhuanlan.zhihu.com/p/565945383
https://www.cnblogs.com/chadlas/articles/15706231.html