MUTATED XSS

WHAT IS MUTATED XSS?

Mutated XSS (Cross-Site Scripting) refers to an advanced form of XSS attack where malicious scripts are dynamically transformed or obfuscated to bypass traditional security filters, such as input sanitization or WAFs (Web Application Firewalls). This is often achieved by encoding or manipulating the payload in creative ways that ensure it is processed correctly by the browser but not detected by security measures.

HOW DOES MUTATED XSS WORK?

Input Filtering – The application tries to sanitize user input to prevent XSS.

Mutation – The browser or server modifies the input unexpectedly, altering its structure.

Execution – The mutated input bypasses security filters and executes as a script.

Impact – Attackers can steal data, hijack sessions, or perform other malicious actions.

MITIGATION FOR MUTATED XSS:

CSP: Use Content Security Policy to control script execution sources.

Sanitize/Encode: Sanitize user input and encode output to prevent malicious code interpretation.

Modern Frameworks: Leverage frameworks like React or Angular with built-in XSS protection.

Regular Audits: Conduct frequent security audits and use automated tools to detect vulnerabilities.

CONCLUSION:

Mutated XSS is a sophisticated attack that exploits how browsers or applications modify input before execution, allowing malicious scripts to bypass security filters. Since traditional sanitization methods may fail against mutation, it is crucial to implement strong defenses like Content Security Policy (CSP), DOM-Purify, and proper input encoding. Developers should avoid using risky methods like inner-HTML and ensure thorough security testing to prevent such vulnerabilities.