Low

源码分析

<?php

if( isset( $_GET[ 'Login' ] ) ) {
    // 获取get传参
    $user = $_GET[ 'username' ];
    $pass = $_GET[ 'password' ];

    // md5加密
    $pass = md5( $pass );

    // 数据库查询语句
    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
    // 查询，查到就返回正确结果，查不到报错结果
    $result = mysql_query( $query ) or die( '<pre>' . mysql_error() . '</pre>' );

    // 基本识别，正确就返回Welcome，错误就返回Username
    if( $result && mysql_num_rows( $result ) == 1 ) {
        $avatar = mysql_result( $result, 0, "avatar" );

        echo "<p>Welcome to the password protected area {$user}</p>";
        echo "<img src=\"{$avatar}\" />";
    }
    else {
        echo "<pre><br />Username and/or password incorrect.</pre>";
    }
    mysql_close();
}
?>

破解

破解的思路：

1.暴力破解，直接调用字典进行破解

// 因为没有任何认证，直接破解无需顾忌什么。
// 尝试进行登录，截取到下面的URL：
http://127.0.0.1/vulnerabilities/brute/?username=name&password=123456&Login=Login
// 其中，出现关键变量，也即是账户信息：
username=name&password=123456
能更迭的是俩个变量：username和password
// 尝试使用BP进行暴力破解

Burp操作

Medium

源码

<?php

if( isset( $_GET[ 'Login' ] ) ) {
    // Sanitise username input
    $user = $_GET[ 'username' ];
    $pass = $_GET[ 'password' ];
    // 将传入的特殊字符进行转义处理，例如加斜杠
    $user = mysql_real_escape_string( $user );
    $pass = mysql_real_escape_string( $pass );

    // 加密
    $pass = md5( $pass );

    $query  = "SELECT * FROM `users` WHERE user = '$user' AND password = '$pass';";
    $result = mysql_query( $query ) or die( '<pre>' . mysql_error() . '</pre>' );

    if( $result && mysql_num_rows( $result ) == 1 ) {
        $avatar = mysql_result( $result, 0, "avatar" );
        echo "<p>Welcome to the password protected area {$user}</p>";
        echo "<img src=\"{$avatar}\" />";
    }
    else {
        sleep( 2 );
        echo "<pre><br />Username and/or password incorrect.</pre>";
    }
    mysql_close();
}
?>

解题

思路：
    和上面相比，多了一个转义语句，这道题目相当与加了一个屏障
    防止特殊语句的注入，单仍然无法防止暴力破解
    解题思路和LOW相同，使用字典破解即可
    具体步骤不赘述

height

源码

<?php

if( isset( $_GET[ 'Login' ] ) ) {
    // Token唯一身份认证（目前最大麻烦）
    checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

    // Sanitise username input
    $user = $_GET[ 'username' ];
    $pass = $_GET[ 'password' ];
    // 去除反斜杠、转义字符
    $user = stripslashes( $user );
    $pass = stripslashes( $pass );
    // 转义掉特殊字符，防止sql注入
    $user = mysql_real_escape_string( $user );
    $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();

?>

解题

针对Token的解决思路：实时捕获Token并且加入信息提交
Token本身是随机生成的，用于防止直接的暴力破解

=>使用BP解决Token的动态捕获和返还问题

新版BP貌似没有带单线程攻击，使用旧版BP即可

难度等级3的BP攻击

Impossible

源码

<?php
if( isset( $_POST[ 'Login' ] ) ) {
    // Token唯一身份认证
    //检查反CSRF令牌
    checkToken( $_REQUEST[ 'user_token' ], $_SESSION[ 'session_token' ], 'index.php' );

    // 清理用户名和密码输入
    $user = $_POST[ 'username' ];
    $pass = $_POST[ 'password' ];
    $user = stripslashes( $user );
    $pass = stripslashes( $pass );
    $user = mysql_real_escape_string( $user );
    $pass = mysql_real_escape_string( $pass );

    $pass = md5( $pass );

    //默认值
    # 登录失败总数
    $total_failed_login = 3;
    # 锁定时间
    $lockout_time       = 15;
    # 账户锁定
    $account_locked     = false;

    //检查数据库（检查用户信息）    
    # 准备SQL查询语句，:user是占位符
    $data = $db->prepare( 'SELECT failed_login, last_login FROM users WHERE user = (:user) LIMIT 1;' );
    # 用参数绑定将变量 $user 与 :user 占位符进行关联
    $data->bindParam( ':user', $user, PDO::PARAM_STR );
    # 上两句合起来就是一句完整的sql语句
    # 执行查询语句
    $data->execute();
    # 默认从执行方法取出一行数据
    $row = $data->fetch();

    
    //检查用户是否已被锁定。
    # 判断用户是否被锁定
    # 如果被锁定：阻止其登录
    
    # # $data->rowCount() == 1 
    #  ==> 判断用户是否存在
    #  - 判断之前查询的结果中是否返回一行数据 
    
    # # $row[ 'failed_login' ] >= $total_failed_login
    #  => 获取之前用户尝试登录的失败次数
    #  - 判断 $row 变量中的 failed_login 字段的值是否大于等于 $total_failed_login 变量的值
    #  - 这句就是限制访问次数的，限定3次锁定
    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>";
        //用户被锁定。请注意，使用此方法将允许用户枚举！
        //echo"<pre><br/>由于登录错误太多，此帐户已被锁定。</pre>"；


        //计算何时允许用户再次登录
        # 计算阻止登陆的时间
        $last_login = $row[ 'last_login' ];
        $last_login = strtotime( $last_login );
        $timeout    = strtotime( "{$last_login} +{$lockout_time} minutes" );
        $timenow    = strtotime( "now" );

        //检查是否已经过了足够的时间，是否还没有锁定帐户
        # 检测当前用户登录的时间是否大于阻止登录的时间
        if( $timenow > $timeout )
            $account_locked = true;
    }

    # 从用户表当中检测登录的用户名和密码是否正确
    $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...
    // 如果是有效登录
    if( ( $data->rowCount() == 1 ) && ( $account_locked == false ) ) {
        // Get users details
        // 获取用户详细信息
        $avatar       = $row[ 'avatar' ];
        $failed_login = $row[ 'failed_login' ];
        $last_login   = $row[ 'last_login' ];

        // Login successful
        // 登录成功
        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?
        // 自上次登录以来，帐户是否已被锁定？
        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
        // 重置错误登录计数
        $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
        // 登录失败
        sleep( rand( 2, 4 ) );

        // Give the user some feedback
        // 给用户一些反馈
        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
        // 更新错误登录计数
        $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
    // 设置上次登录时间
    $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
// 生成反CSRF令牌
generateSessionToken();

?>