Safe Browsing 101: What Is a Cross-Site Scripting Attack?

Many users naively believe they can browse the Internet, and as long as they don’t click on anything, they are safe. Unfortunately, that is not the case. Cross-site scripting (XSS) attacks are one of many malicious threats looming in the web world—in fact, XSS vulnerabilities are rampant out there. Read and learn how to browse as safely as possible.

What Are XSS Attacks?

The Open Web Application Security Project (OWASP) describes XSS attacks as injection attacks, where nefarious code is injected into a trustworthy site: “XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser-side script, to a different end user.” XSS vulnerabilities are widespread—basically anywhere users input data into a web application where the output is not validated or encoded.

What Happens When You Experience a XSS Attack?

In an XSS attack, the attacker inserts malicious code into otherwise trusted content, and the user’s browser assumes the content is from a trusted source and gives the code access to session tokens, cookies, and other sensitive information. Attackers can gather this data and use it to perform more advanced attacks like key logging, identity theft, and phishing.

How Do I Protect My Organization?

Although XSS vulnerabilities are everywhere, they’re also easy to test for. With an experienced security team or the help of a third-party security provider, you can run an automated vulnerability scan to determine whether your site or web application is vulnerable to XSS. OWASP also provides an XSS Prevention Cheat Sheet that provides specific rules to prevent an XSS attack, like Never Insert Untrusted Data Except in Allowed Locations.

Make Browsing as Safe as Possible

Just knowing about the existence of XSS attacks is the first step to combatting them. Sit down with your security team and go over the OWASP cheat sheet, scan your site and web applications for XSS vulnerabilities, and make sure your staff are aware of the risks of XSS threats. Combined, these strategies will get you one step closer to safe browsing.