offensive-jwt

Name: offensive-jwt
Availability: InStock
Author: riparino

Analyze JWT implementations for misconfigurations and weak signing vulnerabilities.

1|Updated Apr 27, 2026

Search Tags:#authentication #jwt #web-security #token-security #vulnerability-testing #jwt-tooling

Ready to run

npx skills add https://github.com/riparino/Claude-Cyber --skill offensive-jwt-riparino

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: offensive-jwt
Source: https://github.com/riparino/Claude-Cyber/tree/main/Claude-Red/Skills/offensive-jwt
Command: npx skills add https://github.com/riparino/Claude-Cyber --skill offensive-jwt-riparino

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

JWT-based systems often suffer from misconfigurations and weak verification that enable token forgery, confusion attacks, and data leakage. This Skill helps security testers identify and remediate these weaknesses in a controlled environment.

Core Features & Use Cases

Algorithm weakness detection: identify alg:none, alg downgrade, and confusion between RS256/HS256.
Header and claim validation checks: verify presence and validation of kid/jku/x5u, jwk, iss, aud, exp, iat, nbf.
Remediation guidance: provide actionable fixes and secure token design examples.

Quick Start

Provide a real JWT from the target application to begin the vulnerability assessment.

Frequently Asked Questions about offensive-jwt

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I test JWT vulnerabilities like alg:none and algorithm confusion?▼

Testing JWT algorithm confusion requires analyzing token implementations for weak signing and misconfigurations like alg:none or RS256/HS256 downgrade attacks. You can identify these vulnerabilities by providing a real token to evaluate header and claim validation flaws.

How do I check if my JWT header and claims are validated correctly?▼

Checking JWT header and claim validation involves verifying the presence and enforcement of kid, jku, x5u, jwk, iss, aud, exp, iat, and nbf. Proper analysis detects missing claim checks and token binding weaknesses across server-side and client-side validation scenarios.

What is the best way to detect JWKS cache issues and token binding weaknesses?▼

Detecting JWKS cache issues and token binding weaknesses requires analyzing JWT implementations for misconfigurations in key handling. Security testing identifies these flaws by evaluating how applications process token headers and validate claims during authentication.

Can I use this for both web and mobile API token security testing?▼

Yes, you can use JWT security testing for both web and mobile applications that use tokens for authentication, session management, or API access. The analysis covers server-side and client-side validation scenarios to identify misconfigurations and weak verification.

How do I get remediation guidance for weak JWT signing and misconfigurations?▼

To get remediation guidance for weak JWT signing, you analyze the token to identify vulnerabilities and then apply actionable fixes. Secure token design examples are provided to correct misconfigurations, algorithm weaknesses, and missing claim validations.