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zseano:escalation

Bug Chaining & Escalation

Individual low/medium bugs often chain together into critical impact. Always ask: can this go further?

Common Chains

Chain Result
Open Redirect + OAuth Token theft = account takeover
Self-XSS + CSRF Stored XSS affecting other users
XSS + no email change confirmation Account takeover
CSRF + email change Account takeover
SSRF + open redirect Internal network access
IDOR + mass enumeration Data breach
File upload (SVG) + same domain XSS on main domain
Clickjacking + CSRF State change without user's knowledge
Host header injection + password reset Intercept reset token

Raising Severity

  • Low bugs alone may be informational – find the chain that makes them critical
  • Self-XSS becomes high if you can deliver it via CSRF
  • Open redirect becomes critical if chained with OAuth
  • CORS misconfiguration + sensitive API endpoint = high/critical
  • IDOR on non-sensitive data + mass enumeration = data breach = high

Impact to Report

Always frame bugs in terms of what an attacker can actually do:

  • “Attacker can read all users' private messages” (data breach)
  • “Attacker can take over any account without interaction” (ATO)
  • “Attacker can access the admin panel and modify all user data” (full compromise)

Generic impact (“this could be used for phishing”) is weak. Show the chain.

Post-Fix Testing

  • After a bug is fixed, test the exact fix
  • Devs usually only fix the specific reported endpoint
  • Check if the root cause is patched everywhere in the app
  • The same code pattern is often reused – look for it elsewhere

See Also

zseano/escalation.txt · Last modified: by drew

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