Cross Site Scripting (Persistent) - Spider

Cross Site Scripting (Persistent) - Spider vulnerability detected. This detector identifies locations where previously injected persistent XSS payloads are retrieved and executed during the spider/crawling phase, confirming that stored malicious scripts are being rendered without proper sanitization.

This finding confirms successful persistent XSS exploitation where stored malicious payloads execute when pages are accessed. The spider phase verifies that injected scripts survived storage and are being rendered to users without neutralization. Attackers exploit this by injecting scripts into forums, comments, profiles, or any user-generated content areas. Every user viewing the compromised page becomes a victim, with their browsers executing the attacker’s code, enabling mass account compromise, session theft, and automated malware distribution.

Apply proper output encoding for all stored user content based on the rendering context (HTML entity encoding, JavaScript escaping, URL encoding). Implement Content Security Policy headers to block inline scripts and restrict script sources. Use template engines with automatic escaping enabled by default. Perform input validation on data entry and output sanitization on data retrieval. Review all locations where user-supplied data is displayed and ensure proper encoding is applied consistently.