How do XSS vulnerabilities work?-JS Tutorial-php.cn

Home

Web Front-end

JS Tutorial

How do XSS vulnerabilities work?

王林

Feb 19, 2024 pm 07:31 PM

principlexss attackCross-site scripting attack

How do XSS vulnerabilities work?

What is the principle of XSS attack, specific code examples are needed

With the popularity and development of the Internet, the security of Web applications has gradually become the focus of attention. Among them, Cross-Site Scripting (XSS) is a common security vulnerability that web developers must pay attention to.

XSS attack is to inject malicious script code into the web page and execute it in the user's browser. This way the attacker can control the user's browser, obtain the user's sensitive information, or perform other malicious operations. . XSS attacks can be divided into three types: storage, reflection and DOM.

A stored XSS attack is when the attacker stores malicious script code in the database of the target website. When the user browses the attacked page, the server sends the malicious script to the user's browser for execution. This attack can steal users' sensitive information, such as login credentials, personal data, etc.

Reflected XSS attack is when the attacker constructs a malicious URL and sends the URL containing malicious script code to the target user. After the user clicks on the URL, the server will return the malicious script code as a parameter to the user's browser, and the browser will execute the script. This type of attack is commonly seen on phishing websites and social engineering attacks.

DOM-type XSS attacks are carried out by modifying the DOM structure of the page. The attacker constructs a URL that contains malicious script code. When the user clicks on this URL, the browser will execute the script and change the DOM structure of the page, thus achieving the attack. This attack method is common in some highly interactive web applications, such as online editors, message boards, etc.

The following uses specific code examples to demonstrate the principles of XSS attacks.

Suppose there is a webpage with a guestbook function, where users can post messages and display them. The following is the code for a simple message display function:

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>留言本</title>
</head>
<body>
    <h1 id="留言本">留言本</h1>
    <div id="messages">
        <!-- 留言内容展示在这里 -->
    </div>
    <form action="save_message.php" method="POST">
        <input type="text" name="message" placeholder="请输入留言">
        <input type="submit" value="提交留言">
    </form>
</body>
</html>

In the above code, after the user enters the message content in the text box and clicks the "Submit Message" button, the message will be sent to save_message. php to save. The following is the code of save_message.php:

<?php
$message = $_POST['message'];
// 实现留言的保存操作，略...
echo "<div>" . $message . "</div>";
?>

In this simple example, the message is stored on the server side, and the message content is dynamically displayed on the . However, without proper verification and filtering measures, attackers can inject malicious script code into the message content to conduct XSS attacks.

For example, an attacker may enter the following content as the message content:

<script>
    alert('你的帐号已被攻击');
    // 或者发送用户的cookie信息到攻击者的服务器
</script>

When other users browse the guestbook page, this malicious script code will be dynamically generated into <div> to execute in their browser. This will pop up a dialog box prompting the user that their account has been attacked. <p>To prevent XSS attacks, web developers need to perform input validation and output filtering. Input validation refers to checking the data entered by the user to ensure that it conforms to the expected format and content. Output filtering refers to processing the data to be output to the page and escaping special characters in it to protect the security of the user's browser. </p> <p>To sum up, the principle of XSS attack is to perform malicious operations in the user's browser by injecting malicious script code. To protect the security of web applications, developers should pay attention to input validation and output filtering to prevent XSS attacks from occurring. </p> </div>

The above is the detailed content of How do XSS vulnerabilities work?. For more information, please follow other related articles on the PHP Chinese website!

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

趣谈ChatGPT原理及算法Apr 27, 2023 pm 08:46 PM

去年12月1日，OpenAI推出人工智能聊天原型ChatGPT，再次赚足眼球，为AI界引发了类似AIGC让艺术家失业的大讨论。ChatGPT是一种专注于对话生成的语言模型。它能够根据用户的文本输入，产生相应的智能回答。这个回答可以是简短的词语，也可以是长篇大论。其中GPT是GenerativePre-trainedTransformer（生成型预训练变换模型）的缩写。通过学习大量现成文本和对话集合（例如Wiki），ChatGPT能够像人类那样即时对话，流畅的回答各种问题。（当然回答速度比人还是

深入解析MySQL MVCC 原理与实现Sep 09, 2023 pm 08:07 PM

深入解析MySQLMVCC原理与实现MySQL是目前最流行的关系型数据库管理系统之一，它提供了多版本并发控制（MultiversionConcurrencyControl，MVCC）机制来支持高效并发处理。MVCC是一种在数据库中处理并发事务的方法，可以提供高并发和隔离性。本文将深入解析MySQLMVCC的原理与实现，并结合代码示例进行说明。一、M

深入解析Struts2框架的工作原理与实现方式Jan 05, 2024 pm 04:08 PM

解读Struts2框架的原理及实现方式引言：Struts2作为一种流行的MVC（Model-View-Controller）框架，被广泛应用于JavaWeb开发中。它提供了一种将Web层与业务逻辑层分离的方式，并且具有灵活性和可扩展性。本文将介绍Struts2框架的基本原理和实现方式，同时提供一些具体的代码示例来帮助读者更好地理解该框架。一、框架原理：St

Golang实现继承方法的基本原理和方式Jan 20, 2024 am 09:11 AM

Golang继承方法的基本原理与实现方式在Golang中，继承是面向对象编程的重要特性之一。通过继承，我们可以使用父类的属性和方法，从而实现代码的复用和扩展性。本文将介绍Golang继承方法的基本原理和实现方式，并提供具体的代码示例。继承方法的基本原理在Golang中，继承是通过嵌入结构体的方式实现的。当一个结构体嵌入另一个结构体时，被嵌入的结构体就拥有了嵌

深入探究Maven生命周期的功能和机制Jan 04, 2024 am 09:09 AM

深入理解Maven生命周期的作用与原理Maven是一款非常流行的项目管理工具，它使用一种灵活的构建模型来管理项目的构建、测试和部署等任务。Maven的核心概念之一就是生命周期（Lifecycle），它定义了一系列阶段（Phase）和每个阶段的目标（Goal），帮助开发人员和构建工具按照预定的顺序执行相关操作。Maven的生命周期主要分为三套：Clean生命周

深入理解Java反射机制的原理与应用Dec 23, 2023 am 09:09 AM

深入理解Java反射机制的原理与应用一、反射机制的概念与原理反射机制是指在程序运行时动态地获取类的信息、访问和操作类的成员（属性、方法、构造方法等）的能力。通过反射机制，我们可以在程序运行时动态地创建对象、调用方法和访问属性，而不需要在编译时知道类的具体信息。反射机制的核心是java.lang.reflect包中的类和接口。其中，Class类代表一个类的字节

了解PHP底层开发原理：基础知识和概念介绍Sep 10, 2023 pm 02:31 PM

了解PHP底层开发原理：基础知识和概念介绍作为一名PHP开发者，了解PHP底层开发原理是非常重要的。正因为如此，本文将介绍PHP底层开发的基础知识和概念，帮助读者更好地理解和应用PHP。一、什么是PHP？PHP（全称：HypertextPreprocessor）是一门开源的脚本语言，主要用于Web开发。它可以嵌入到HTML文档中，通过服务器解释执行，并生成

PHP邮件队列系统的原理和实现方式是什么？Sep 13, 2023 am 11:39 AM

PHP邮件队列系统的原理和实现方式是什么？随着互联网的发展，电子邮件已经成为人们日常生活和工作中必不可少的通信方式之一。然而，随着业务的增长和用户数量的增加，直接发送电子邮件可能会导致服务器性能下降、邮件发送失败等问题。为了解决这个问题，可以使用邮件队列系统来通过串行队列的方式发送和管理电子邮件。邮件队列系统的实现原理如下：邮件入队列当需要发送邮件时，不再直

See all articles