What Is Reflected XSS? How to Know If You Are Attacked by Reflected XSS

Reflected XSS is easier to understand when the core ideas are explained in practical terms. This guide covers what it means, how it works, why it matters, and the main details you should know.

What Is Reflected XSS?

Reflected XSS is a type of cross-site scripting attack. Hackers will insert malicious JavaScript code into a website and then trick viewers into clicking on a link containing the malicious code. The code will be executed in their browser without being stored on the server when users select the link containing this malicious code. From there, the bad guys can access sensitive information such as cookies, session IDs,.

What is Reflected XSS?

Targets of Reflected XSS Attacks

Reflected XSS attacks are performed for the following purposes:

• Stealing user information: Attackers can steal cookies or session tokens, thereby taking control of the victim's account on the websites they are using.
• Perform unwanted actions: Once taken over, the attacker can perform actions such as sending fake messages, changing account information, or even spreading malware to other users.
• Browser Control: Malicious code executed in the victim's browser is a tool for attackers to modify, control the user interface or collect additional data from users without their knowledge.
• Spreading malware: Attackers can use Reflected XSS to spread malware to other computers, creating a network of infected devices.

How Is Reflected XSS Implemented?

The Reflected XSS implementation process is similar to other forms of cross-site scripting attacks, including the following four main steps:

• Step 1: The attacker creates a URL containing malicious code, usually JavaScript. For instance: http://example.com/search?query=.
• Step 2: The attacker sends a malicious link via email, social media, or other means to trick the victim into clicking on it.
• Step 3: When the victim clicks on the link, their browser sends a request to the server with the parameters in the URL. It will respond with the injected malicious code if the web application doesn't validate and handle the input safely.
• Step 4: The malicious code responded from the server will be executed in the victim's browser environment.

How to Check Reflected XSS

Use Automated Tools

You will find many automated tools available today that can help detect Reflected XSS vulnerabilities, such as Burp Suite, OWASP ZAP, and Acunetix. These tools are capable of scanning and analyzing a website's input parameters to determine if they are vulnerable to XSS.

You simply enter a URL and the tool will automatically perform the tests when using these tools. The tool will provide detailed information on how to fix it if a vulnerability is found.

Perform Manual Testing

In addition to using automated tools, it is also important to perform manual testing. Security personnel can test URL parameters by inserting JavaScript code to see if the code is executed.

For instance, you can experiment with input parameters like:

Http://example.com/search?q=alert('XSS').

This indicates that the website may be vulnerable to Reflected XSS if when you select this link and see a warning window appear.

Check All Data Entry Points

One way to check if you are vulnerable to Reflected XSS is to examine each entry point in your application's HTTP requests individually. An entry point is any data in a URL query string, file path, or message body, including parameters and HTTP headers. However, it can be more difficult to exploit HTTP headers for XSS attacks.

Use Random Values

Try sending unique, random alphanumeric values ​​to each data entry point to test whether the response reflects the values. These values ​​should be short and simple enough to pass most input validation, containing only letters and numbers. They should also have enough characters to reduce the chance of a random match, so values ​​around eight characters work best.

Conclude

From stealing personal information to conducting phishing attacks, Reflected XSS is a serious threat that everyone needs to pay attention to, especially businesses. Hopefully, through this article of this guide, readers have learned more about a popular form of cross-site scripting attack today.

Final Thoughts

The most reliable way to handle reflected XSS is to follow the process in order, verify each important setting, and test the result before moving on. Use the guidance above as a practical reference, then adjust the details for your device, software version, or specific goal.