How To Prevent XSS and CSRF

Cross-site scripting (also known as XSS) and cross-site request forgery (also known as CSRF) are two of the most common attacks hackers perform online. Both work in a similar fashion and can compromise vital data from websites and users. For that reason, you need to learn how to prevent XSS and CSRF attacks.

Sanitizing your code, working with the latest frameworks, and scanning for vulnerabilities is the best way to prevent XSS and CSRF attacks from taking place. Users should do their part by updating their browsers, following cybersecurity best practices, and storing little essential data online.

You can only defend yourself if you understand an attack, so we’ll explain how and why XSS and CSRF attacks happen. We’ll also explain how companies and users can protect themselves from threat actors performing these actions.

Why Do XSS and CSRF Attacks Happen?

Hackers prey on the same circumstances to perform  XSS and CSRF attacks. They target vulnerable websites that have access to data or people who can provide data (without knowing what they’re doing).

The circumstances that allow XSS and CSRF attacks to happen are the following:

  • Poorly coded websites. XSS and CSRF attacks follow similar patterns: they target outdated or poorly coded sites. Companies should frequently audit their websites to make sure they’re not allowing hackers to access their data or users’ data. Doing so is the first line of defense against these attacks.
  • Outdated browsers. Software developers work day and night to fight against the constant stream of hackers trying to make the most out of new vulnerabilities. It’s critical that you update your browser as soon as possible, so you have a fighting chance against the latest hacks coming your way. Certain browsers will warn you when they detect an XSS attack taking place.
  • Unsuspecting users. Unfortunately, it’s impossible to rely on software alone to stop hackers. Users must follow cybersecurity best practices to stay out of harm’s way. Avoiding links you can’t trust is the cornerstone of internet security.

Are XSS and CSRF the Same?

XSS and CSRF are similar – but not quite the same. However, they work in a similar fashion: hackers attempt to inject malicious code into websites to perform these attacks.

Although these cyber attacks don’t work in the exact way, their result is identical: having vital information fall in the hands of threat actors.

The biggest difference between XSS and CSRF attacks is this: XSS can compromise both ends (servers and users), while CSRF is a one-way attack, compromising only one end, meaning it can only force users to perform certain actions without them knowing.

Fortunately, following good cybersecurity practices is enough to prevent XSS and CSRF attacks. Both companies and users can do their part to protect data from threat actors.

Preventing XSS and CSRF

1. Make Your Team Aware of the Issue

Every employee should know how to conduct themselves online. In other words, they should train in cybersecurity to follow best practices – even if they’re not in the IT department.

Doing so will help them be aware of threat actors, including those performing XSS and CSRF attacks. By understanding the motive and procedure behind these vulnerabilities, they’ll do their best to stay safe.

Users are responsible for their behavior online, although that doesn’t exempt companies from having lousy security practices.

2. Inspect Your Site for Vulnerabilities

You must look for places where your code isn’t at its best, the small cracks where hackers could plant a small XSS attack that could do a lot of damage. In fact, the key to defending your site from these attacks is to routinely scan for vulnerabilities.

Scanning comes in two ways: manually and automatically. It’s safe to say that manually scanning for vulnerabilities is a long and tedious process. Therefore, you can use software to do the first scan.

The best vulnerability scanners are:

  • Burp Suite
  • Nessus

Unfortunately, the only way to thoroughly inspect for vulnerabilities is to do so manually – no matter how tedious that could be.

3. Sanitize Your Code

Simply put, XSS entails a hacker injecting malicious code into a website. Programmers have to overlook certain cybersecurity guidelines for that to happen. Otherwise, it’s rather difficult for threat actors to inject your site that way.

For that reason, you have to take the time to sanitize your HTML, CSS, and JavaScript, along with other coding languages you may be using. In other words, you have to prevent certain input formats from messing with your site’s code.

If you don’t want to edit your code for whatever reason, you can use tools such as HTML Purifier, Java Encoder, PHP Anti-XSS, and more.

4. Work With the Latest Frameworks

Programming in JavaScript is a double-edged sword: it provides countless tools to better your website, although it could also leave a minefield’s worth of opportunities for threat actors to act.

Fortunately, developers look for ways to prevent hackers from harming your site. Some of the latest frameworks include tools to help you defend your projects from the get-go.

For example, React works in a way that mitigates certain XSS attempts.

Nevertheless, that doesn’t mean relying on certain frameworks puts you out of harm’s way. You still have to deploy certain features to fully fortify your website.

5. Use Tokens for Protection

Using tokens to validate requests is one of the easiest ways to protect users from CSRF attacks. Although users never realize what’s going on, they have an extra layer of protection from hackers.

The main gist is simple: Each session receives a unique token (e.g., one is generated when you log in). This token will work as a secret, randomly generated, one-time-use password. Every time a logged-in user wants to do something (e.g., change their email, purchase something, etc.), the server has to verify that token.

How do tokens prevent CSRF attacks? A unique token is attached to each session, and a request to verify that token is sent to the server every time you try to do something. When you fall for a CSRF attack, the request made by the threat actor will not match the token you have, making the server refuse that request.

6. Employ SameSite Cookies

A cookie is generated and stored when you visit a website to help servers remember who you are. Threat actors abuse that mechanism to perform CSRF attacks, pushing developers to create SameSite cookies to prevent that from happening.

How do SameSite cookies work? Programmers can choose SameSite cookies to be strict, lax, or none. If the first one is chosen, any request made by third-party websites will be performed as if no cookies at all existed, meaning your stored data will not be used when performing a request.

In other words, it allows websites to hide cookies from threat actors trying to perform a CSRF attack. When no vital information is at stake, developers can disable the SameSite cookie feature from a webpage.

How Can Users Prevent XSS and CSRF Attacks

1. Never Click Something You Can’t Trust

One of the cardinal rules of cybersecurity is to never open any links or attached files you receive from people you can’t trust.

Chances are, the next data breach you’ll face will make its way from your inbox.

As you now know, you’re one wrong click away from falling prey to an XSS or CSRF attack, which could help hackers get vital information from you.

2. Log Out and Never Save Credentials

What if you’re not the only one who uses your computer? You may have friends, family, or colleagues that want to check their emails from one of your devices.

While that should be strictly forbidden for work devices, that doesn’t mean personal devices aren’t out of harm’s way.

For that reason, clearing your cookies, never saving login credentials to your browser, and logging out of potentially-critical websites (e.g., banking sites) is a must.

In a worst-case scenario (when one of these attacks succeeds), you want to minimize the amount of information that could be delivered to threat actors. Doing what’s stated above will help you cut your losses.

3. Keep Your Browser up to Date

We often think about updating our antivirus, firewall, VPN, and similar software. However, that leaves one critical program outside our scope: the link between our computer and the internet.

We have a handful of secure browsers to choose from, though that won’t make that much of a difference if you don’t update it. Hackers frequently look for new and ingenious ways of harming your computer, so engineers have to find how to stop them. That often results in a software update.

Software companies are doing their part to protect their site from attacks, so you should take care of your end and update your browser.


Companies should sanitize their code, work with the latest frameworks, and regularly inspect for issues to prevent XSS and CSRF attacks. Users should do their part: update their browsers, delete cookies, and follow cybersecurity best practices. Reducing the risk of these attacks involves storing the least amount of data online possible.

Herman McCargo

Herman is a Microsoft Certified Security Engineer and Cybersecurity Specialist. He’s been in the technology field for over 20 years and has expertise working with the most critical technology infrastructures. He has a deep understanding of cyber risks, threat mitigation and prevention, and overseeing infrastructure.