offensive-jwt SKILL.md skillA
offensive-jwt from miosa-osa/osa is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add miosa-osa/osa/offensive-jwt@git:20260913.e13b6b8Pins git:20260913.e13b6b8 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- miosa-osa/osa
- Path
priv/skills/offensive-jwt/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260913.e13b6b8, committed Sep 13, 2026
- Size
- 11,947 bytes
- Repository stars
- 78
- License
- Apache-2.0
JWT attack methodology for penetration testers. Covers algorithm confusion (alg:none, RS256→HS256), weak HMAC secret brute force, kid parameter injection (SQLi, path traversal), jku/x5u/jwk header injection, JWKS cache poisoning, JWS/JWE confusion, timing attacks, and mobile JWT storage extraction. Use when testing JWT-based authentication, hunting auth bypass via token manipulation, or evaluating JWT implementation security in web or mobile apps.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
## Overview Comprehensive JWT attack checklist for offensive security engagements. Follow steps in order; apply each technique to the current target context and track which items have been completed. ## Quick Reference: Misconfigurations to Check - Algorithm set to `none` — signature verification bypassed entirely - Algorithm switching between `RSA` and `HMAC` (confusion attack) - Weak or guessable HMAC secret (brute-forceable) - `kid`, `jku`, `jwk`, `x5u` header parameters accepted without validation - Expired or tampered tokens accepted by server - Sensitive data stored unencrypted in payload Useful tool: [JWT Tool](https://github.com/ticarpi/jwt_tool) ## Mechanisms JWTs (RFC 7519) consist of three Base64URL-encoded parts: `header.payload.signature`. **Signing algorithms:** | Algorithm | Type | Notes | |-----------|------|-------| | HS256/384/512 | Symmetric HMAC | Shared secret; confusion target | | RS256/384/512 | Asymmetric RSA | Public key can be misused as HMAC secret | | ES256/384/512 | Asymmetric ECDSA | | | PS256/384/512 | RSASSA-PSS | | | EdDSA (Ed25519/Ed448) | Asymmetric | | | none | Unsigned | Critically insecure | **Additional pitfalls:** …
Read the whole file at its exact version.
How to install
mdr add miosa-osa/osa/offensive-jwt@sha256:b284c9550e89fb77The line at the top of this page pins the label git:20260913.e13b6b8, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_mmjcxdmpnhaewtsj)
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Versions
The registry has recorded 1 version of this file, committed on Sep 13, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (11947 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
miosa-osa/osa · 78 stars · license Apache-2.0 · pushed 2026-10-29 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_mmjcxdmpnhaewtsj GET https://markdownregistry.com/api/v1/resolve?ref=miosa-osa/osa/offensive-jwt GET https://markdownregistry.com/api/v1/blob/b284c9550e89fb77b9ded6027e90ca454b4f62f8cb665dd917c8e9307cdb713e
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.