Prevent Cross-site Scripting with Kiuwan Code Security

What is Cross-site Scripting?

According to OWASP Top 10, XSS is the second-most prevalent issue found in the majority of web applications. By using XSS, attackers can bypass the Same Origin Policy (SOP) in a vulnerable application by entering malicious code which is mistakenly interpreted as user input. This can be done with technologies like VBScript, ActiveX, Flash and even CSS, but JavaScript attacks are the most common.

XSS differs from SQLi because it does not target the database of web applications; it mostly limits itself to their front end. 

These kinds of attack can be non-persistent, persistent and DOM-based. The consequences of XSS attacks can be very damaging, especially when combined with social engineering.

Websites or web interfaces can become corrupted and unsafe. Cookies and authentication information can be stolen, leading to identity theft. By hacking a vulnerable company website, attackers can gain control of the company’s computer clients.

Cookie theft

An attacker could post malicious JavaScript in the comment section of a forum to steal cookies from users of the same website.

Website damage

Hackers can edit the visual appearance of the website and use embarrassing images or messages to target the owners of the website.

Phishing

Injected JavaScript on a webpage could redirect users to other websites or phishing sites, where their data can be stolen.

Keylogging

An attacker could record keyboard events into his own server to steal sensitive information, like passwords.

Client access

In combination with social engineering, users could be unknowingly forced to give hackers access to their webcam, microphone or even file system.

Sanitize
HTML inputs

… specify which tags are designed as “safe” in the HTML documents created by user inputs, by blacklisting and whitelisting. Useful for websites that rely on user inputs, like forums, but it should not be used alone to combat XSS.

Escape
user input

… or encode the data on output. Ensure the data an application has received is safe before making it available to other users. Certain characters will not be rendered and will not be interpreted in a malicious way.

Use Content Security Policy (CSP)

… adding the HTTP response header Content-Security-Policy allows website owners to declare which content sources are trusted or not and can be loaded onto the web applications.

Use a SAST
solution

…with Static Application Security Testing, you can make your applications more secure already in the source code. Try out Kiuwan Code Security today and scan for XSS vulnerabilities in your code.