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hunt-clickjacking

Hunt Clickjacking — missing X-Frame-Options / CSP frame-ancestors lets an attacker embed the target page in an invisible iframe and trick victims into clicking buttons they cannot see (UI redressing). Targets: login flows, money transfers, account settings, OAuth confirmation pages. Confirm by fetching the page, then PROVE it frames in a real browser and a sensitive state-changing action survives the cross-site context (SameSite cookies / framebusting JS can defeat it) — header-absence alone is not a finding.

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SKILL.md
Quality
Evals
Security

What is Clickjacking

Clickjacking (UI Redressing) lets an attacker load a target page inside a transparent iframe on a malicious site. The victim sees the attacker's decoy UI but clicks the hidden target UI beneath it. No JavaScript on the target is required.

Highest-value targets:

  • Login / authentication pages — force login with attacker credentials
  • Money transfer / checkout / "confirm payment" buttons
  • Account settings (email change, password change, 2FA disable)
  • OAuth / social-login "Authorize app" confirmation dialogs
  • Admin actions (delete, promote user, change role)

Protection Headers

Two mechanisms prevent framing:

X-Frame-Options: DENY              # strongest — blocks all framing
X-Frame-Options: SAMEORIGIN        # allows same-origin frames only
Content-Security-Policy: frame-ancestors 'none'     # CSP equivalent of DENY
Content-Security-Policy: frame-ancestors 'self'     # CSP equivalent of SAMEORIGIN

If NEITHER is present, the page is frameable from any origin.

How to Test

Header-absence is the trigger for investigation, not the finding. Two steps:

Step 1 — Header check (screening). Fetch the target page and inspect the response headers:

curl -sI https://target.example/account/transfer | grep -iE 'x-frame-options|content-security-policy'

If BOTH X-Frame-Options and CSP frame-ancestors are absent, the page is a candidate. If either is present and restrictive (DENY/SAMEORIGIN/frame-ancestors 'none'|'self'), stop — it's protected.

Step 2 — Prove it actually frames and clicks (required for a real finding). Build a minimal PoC and load it in a real browser:

<!doctype html>
<h1>Win a prize — click below</h1>
<iframe src="https://target.example/account/transfer"
        style="opacity:0.1;position:absolute;top:0;left:0;width:1000px;height:800px"></iframe>

Confirm ALL of the following, or it is not exploitable:

  • The page actually renders inside the iframe (no framebusting JS that blanks/redirects it — e.g. if(top!==self) breakout, or a Sec-Fetch-Dest/JS frame check).
  • The sensitive action still works while framed — critically, the action must succeed cross-site. If it relies on a session cookie set SameSite=Lax or SameSite=Strict (the modern default), the cookie is not sent on the cross-site framed request, and the clickjack fails. Verify the victim's authenticated state carries into the frame.
  • The target is a state-changing action (transfer, settings/email/password change, 2FA disable, OAuth authorize, admin action), not a read-only page.

Strategy: target the most sensitive action pages first — severity scales directly with what the victim is tricked into doing.

False Positives

  • Public, read-only pages (home/marketing) lacking frame protection are low/informational — no sensitive action to redress.
  • APIs and non-HTML endpoints (JSON, images) are not clickjacking targets.
  • Header-absence alone is NOT a finding. SameSite cookies, framebusting JS, or the lack of any sensitive framed action can each fully defeat it — which is why Step 2 is mandatory.

Proof Requirements

A valid clickjacking report shows: (1) the target page rendered inside an attacker-controlled iframe in a real browser, (2) a sensitive state-changing action reachable by a framed click while the victim is authenticated (cookies survive the cross-site context), and (3) a screenshot/recording of the overlay. Reporting missing headers with no working frame PoC is a documentation-quality issue, not a vulnerability.

Repository
elementalsouls/Claude-BugHunter
Path

skills/hunt-clickjacking/SKILL.md

Commit

6b9c96e

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