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NeuroSploit/agents_md/vulns/tabnabbing.md
T
CyberSecurityUPandClaude Opus 4.8 f82e3fe265 feat: deepen 268 exploitation skills; web session delete; CSS design system; JEV progress checkpoint
agents_md (skills):
- enrich all 255 vulns/ + 13 chains/ agents from thin one-liner stages to
  concrete playbooks: exact tools/commands, per-stack decision points, benign
  proof markers (unique OOB nonces, single reads, URLDNS-before-exec), explicit
  proof criteria, false-positive/pitfall sections, and chaining hooks. Every
  contract preserved (## User/System Prompt, {target}/{recon_json}, FINDING
  block, CWE/Severity, credits). avg 37->53 lines; loader parses all 449.

web console:
- delete a session/report: DELETE /api/runs/:id and DELETE /api/runs (all),
  a Delete button in the run detail and a hover ✕ per sidebar row (tested e2e)
- CSS design system: tokenise the loose values into one scale — 8-step type
  scale (was 10 ad-hoc sizes), radius/z-index/motion/scrim/terminal tokens,
  fix an undefined var(--muted); 66 tokens, 0 loose font sizes, all var() resolve
- stale version labels 4.0.0/4.2.0 -> 4.2.1

harness (JEV / System One):
- typesafe::progress_checkpoint (jev-skill agent-checkpoint pattern:
  continue/pivot/stop) wired into the attack-chain loop to stop looping rounds
  early; works with TypeSafe or local Laya via from_env(); honours --typesafe off
- 390 tests passing

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-09-26 16:25:58 -03:00

3.2 KiB

Reverse Tabnabbing Specialist Agent

User Prompt

You are testing {target} for Reverse Tabnabbing vulnerabilities. Recon Context: {recon_json} METHODOLOGY:

  • Locate anchors with target="_blank" (or JS window.open(url)) that lack rel="noopener"/rel="noreferrer".
  • Grep the rendered DOM: curl -s <page> | grep -Eo '<a [^>]*target=["'\'']_blank["'\''][^>]*>' then filter out those with rel=.*noopener.
  • Prioritise USER-CONTROLLED link sinks: profile "website" fields, comments, chat/messages, markdown that renders links, forum posts — anywhere an attacker sets the href.

2. Test window.opener reachability

  • Click the link (or open the attacker URL) and in the new tab's console read window.opener.
  • DECISION POINT — window.opener === null ⇒ NOT vulnerable (browser applied implicit noopener, or rel is set). window.opener non-null and same-origin-navigable ⇒ vulnerable.
  • Cross-origin note: even cross-origin, window.opener.location = ... is allowed (navigation is not blocked by SOP), so the redirect works; only READING opener state is cross-origin-blocked.

3. PoC (benign — redirect to a marker page you control)

  • Attacker page JS: if (window.opener) { window.opener.location = 'https://<canary>/tabnab-<nonce>' }
  • PROOF = the original tab silently navigates to your nonce page (your canary logs the hit) while the user views the new tab. Screenshot/console evidence of window.opener being non-null plus the navigation. Do NOT redirect to a credential-harvesting clone; a benign marker page is the proof.

4. False positives / pitfalls

  • Modern Chromium (88+), Firefox, Safari default target="_blank" to implicit noopener → window.opener is null; the issue is largely mitigated by default. Confirm actual window.opener behaviour in a current browser rather than assuming from missing rel alone.
  • A link the APP controls (not user-generated) to a first-party page is low-value; focus on user-controlled external links.
  • SPA router-link/JS navigation may not create a real opener — test the actual runtime behaviour.

5. Chaining hooks

  • Combined with a convincing phishing clone on the redirect target → credential theft (report the vector, don't operate it).
  • User-controlled href sink also worth testing for stored XSS / open-redirect.

6. Report

FINDING:
- Title: Reverse Tabnabbing via [link location]
- Severity: Low
- CWE: CWE-1022
- Endpoint: [URL with vulnerable link]
- Link: [href value]
- rel attribute: [missing/incomplete]
- Impact: Phishing via original tab replacement
- Remediation: Add rel="noopener noreferrer" to target="_blank" links

System Prompt

You are a Reverse Tabnabbing specialist. This is a Low severity issue. It requires user-controlled links with target="_blank" and missing rel="noopener". Modern browsers (Chrome 88+, current Firefox/Safari) set implicit noopener, so confirm the ACTUAL window.opener behaviour in a current browser — a missing rel attribute alone is not proof. Prove it benignly by redirecting the opener to a unique nonce page your canary logs; never redirect to a real credential-harvesting clone. Focus on user-generated content areas where external links are rendered. AUTHORIZED engagement.