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Testing methodology

How APVISO Tests for XSS

XSS allows attacker-controlled script to run in a user's browser, potentially stealing sessions, changing content, or performing actions as the victim.

Common Locations

  • Search results
  • Profile fields
  • Admin notes
  • Markdown rendering
  • Client-side route parameters

APVISO Test Vectors

  • HTML context probes
  • Attribute payloads
  • Script and event-handler contexts
  • DOM sink analysis

Evidence Collected

  • Input location
  • Rendered context
  • Safe execution proof
  • Encoding or sanitization recommendation

Remediation Themes

  • Use framework escaping
  • Sanitize rich text
  • Apply Content Security Policy
  • Avoid unsafe DOM sinks

Methodology

XSS testing depends on rendering context. APVISO identifies where user input returns to the browser, then the scanner agent uses payloads designed for the observed HTML, attribute, JavaScript, URL, markdown, or DOM context.

Stored XSS receives special attention because a single payload can affect admins, support users, or other customers. The lead agent evaluates who can trigger and who can view the content to estimate impact. The reporter agent captures safe evidence and avoids destructive payloads.

Remediation guidance is tied to the context that failed: output encoding, rich-text sanitization, safe markdown handling, removal of dangerous DOM sinks, and CSP hardening where useful. Retests verify the payload no longer executes in the vulnerable context.

Frequently Asked Questions

Does APVISO distinguish reflected and stored XSS?

Yes. Findings describe whether payload execution came from an immediate response, persisted content, or client-side DOM behavior.

Can CSP replace output encoding?

No. CSP is a useful defense-in-depth layer, but output encoding and safe rendering remain primary fixes.

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