Learn how to exploit a stored XSS vulnerability in onclick events, bypassing HTML-encoded angle brackets, double quotes, and escaped single quotes and backslashes. Step-by-step guide for solving the PortSwigger lab challenge

InfoSecWriteUps' platform is  dedicated to providing insights and resources for cybersecurity professionals and enthusiasts. Through articles, tutorials, and security research, InfoSecWriteUps offers insights into cybersecurity vulnerabilities, attack techniques, and defense strategies. Readers can learn about penetration testing, threat intelligence, and incident response to enhance their cybersecurity knowledge and skills.

InfoSec Write-ups

The post explores a stored cross-site scripting (XSS) vulnerability in a web application's comment functionality, focusing on how to bypass sanitization measures that HTML-encode angle brackets and double quotes, and escape single quotes and backslashes. It provides a step-by-step guide to inject a malicious JavaScript payload that triggers when a user clicks the comment author's name. Mitigation strategies include using libraries like DOMPurify for sanitization and replacing onclick event handlers with safer alternatives.

[Write-up] Stored XSS into Onclick Event with Angle Brackets and Double Quotes HTML-encoded and Single Quotes and Backlash Escaped