Cross-site scripting facts for kids

Cross-site scripting (often called XSS) is a type of cyber attack. It happens when a bad actor, called an attacker, tries to sneak harmful computer code into a website. This code then runs in your web browser when you visit that website. Imagine someone putting a secret message into a game you play online. This message isn't part of the game, but it tries to do something sneaky on your computer.

How Does XSS Work?

In an XSS attack, the attacker uses a website that isn't very secure. They hide their harmful code, usually a type of code called JavaScript, within the website. When you visit that website, your web browser doesn't know the code is bad. It runs the harmful JavaScript on your computer.

Think of it like this:

• A website has a comment section.
• An attacker posts a comment, but instead of words, they put in secret code.
• When you read the comments, your browser sees the secret code.
• Your browser thinks it's part of the website and runs the code.

This sneaky code runs on your computer, not on the website's main server. About one out of every three websites might have a small crack where XSS attacks can happen.

What Can an XSS Attack Do?

Even though the attack happens in your browser, it can still cause big problems for the website you are visiting. For example, an attacker might use XSS to:

• Steal your login details: The harmful code could try to trick you into giving away your username and password.
• Take over your account: If the attacker gets your login details, they can log in as you.
• Control the website: If the stolen account belongs to a website administrator, the attacker could gain control of the entire website!

How Can Websites Stop XSS Attacks?

Protecting against XSS attacks is very important for website owners. Here are some ways they can do it:

• Regular Scans: Website owners should regularly check their websites for weaknesses. They can use special tools to scan for XSS vulnerabilities.
• Fixing the Code: If a weakness is found, the website's developers must fix the computer code. This makes it harder for attackers to sneak in their harmful scripts.
• Being Careful with User Input: Websites should always be careful about what users type into forms or comment sections. They need to clean or "sanitize" any text before showing it to others. This removes any hidden harmful code.

Some people think that special tools called "web application firewalls" can stop XSS. While these tools can make attacks harder, they don't fix the actual problem in the website's code. The best way to be safe is to fix the code itself.