Payload Xss Protection Strategies: A Developer’s Handbook

Payload Xss Protection Strategies: A Developer’s Handbook – This blog will help developers understand XSS, its types, how to detect and prevent it. XSS stands for cross-site scripting, a type of vulnerability.

Remember when a vulnerability was discovered in Microsoft Exchange Server that could allow a reflected cross-site scripting (XSS) attack? This RXSS could lead to unauthorized access to email accounts, phishing attacks, and other activities that could change the state of the affected application. XSS attacks are particularly dangerous because they allow attackers to execute malicious code in a user’s browser, potentially leading to the theft of sensitive information or even hijacking an entire account. However, Microsoft has resolved the issue by releasing a patch that addresses the vulnerability. This highlights the importance of updating software and regularly checking for security vulnerabilities.

Payload Xss Protection Strategies: A Developer’s Handbook

XSS stands for “cross-site scripting,” a type of security vulnerability that allows attackers to inject malicious scripts into a web page that other users can see.

Xss And Its Types In Web App Penetration Testing

What if a web application has XSS? When a user visits an application that has a cross-site scripting vulnerability, the attacker’s script is executed by the user’s browser. Unfortunately, this allows an attacker to obtain sensitive information such as login credentials, session tokens, or personal data. It can also enable other malicious actions, such as manipulating page content, redirecting the user to a malicious website, or infecting the user’s system with malware. The potential for danger is limitless!

XSS has several levels. Let’s dive deeper into XSS types in the next section.

In 2019, a security researcher discovered a reflected XSS vulnerability in Google Translator. This vulnerability allows attackers to inject malicious code into translated text, which can then be executed when other people see it. Look at this picture below!

Reflected XSS is a type of cross-site scripting vulnerability that occurs when an application repeats user input in a response without properly validating or encoding it. This attack typically involves the attacker creating a malicious link or form containing a script. When the victim clicks a link or submits a form, their browser executes the script.

Content Security Policy (csp) And Its Bypasses

Let’s say you have an API endpoint that gets a list of articles based on a search query. The server then returns a list of articles in a JSON response that includes the article title, author, and content. Here is an example of vulnerable code that repeats user input without proper coding or validation:

In this example, the $search_query variable is not sanitized or validated and is included directly in the JSON response to the user, making it vulnerable to reflected XSS attacks. So how does an attacker perform the XSS reflected here? An attacker could create a malicious URL that includes a script as a request parameter. See below:

The victim’s browser executes the script and displays an alert box with the message “XSS”. An attacker could use it to steal the victim’s session cookies, passwords, or other sensitive data or perform other malicious actions. Dangerous!

Don’t worry! you can prevent this by using input validation in your code. Here’s how you can sanitize and validate all user input and encode any special characters before including them in the response.

Html Tags Converting Into Entity Characters In Xss

In this improved code, the htmlspecialchars function cleverly encodes any special characters entered by the user, such as , before including them in the JSON response. This input validation method effectively prevents the browser from misinterpreting the input as HTML or JavaScript code and instead displays it as plain text. Read on as I will discuss additional input validation methods in the blog.

In 2018, a security researcher discovered a stored cross-site scripting (XSS) vulnerability in Snapchat that allowed attackers to inject malicious code into business.snapchat.com. The vulnerability could allow an attacker to steal user credentials or perform other malicious actions.

Stored XSS, also known as persistent XSS, is a cross-site scripting attack in which malicious code is permanently stored in the database or server of the target application. Unlike reflected XSS, where malicious code is injected in response to a user request, stored XSS attacks can affect all users who access the affected page or resource. Stored XSS attacks occur when an attacker can send malicious data to a website, for example through a form or comment field, which is then stored and displayed to other users.

Let’s say you have an API endpoint that allows users to leave comments on an article. The server then stores the comments in the database and returns them in a JSON response, including the comment text and author. Here is an example of vulnerable code that stores user input without proper encoding or validation:

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