claude-red is a library of structured skills that give Claude specialized offensive-security methods for areas such as web vulnerabilities, shellcode, exploit development, and identity systems. It is intended for authorized red-team work, bug-bounty triage, security research, CTF preparation, and operator training. Its catalogue contains the project's skills for loading these security specializations into Claude.
Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/SnailSploit/Claude-Rednpx agentmods add skills/snailsploit/claude-red/offensive-jwtWrote 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/snailsploit/claude-red/offensive-jwt)<a href="https://agentmods.dev/skills/snailsploit/claude-red/offensive-jwt"><img src="https://agentmods.dev/badge/skills/snailsploit/claude-red/offensive-jwt/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/snailsploit/claude-red/offensive-jwt"><img src="https://agentmods.dev/badge/skills/snailsploit/claude-red/offensive-jwt.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 13 findings, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high YARA Match · line 46 YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
- high Privilege Escalation · line 138 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 258 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- high Privilege Escalation · line 268 Code accesses credential files (SSH keys, AWS credentials, etc.). This could indicate credential theft attempts.Fix: Remove references to credential paths. Use environment variables or secrets managers. For docs, use placeholder paths (e.g., /path/to/config). Never load .env or token files in production code paths.
- medium Tool Misuse · line 110 Tool defaults are unsafe or overly permissive (e.g. disabled TLS verification, no authentication, world-writable permissions). Unsafe defaults widen the attack surface.Fix: Override unsafe defaults with secure settings (verify=True, auth required, restrictive permissions). Review and harden all tool configurations.
- medium Rogue Agent · line 122 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
- medium Rogue Agent · line 130 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
- medium Data Exfiltration · line 142 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 142 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 145 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 173 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 174 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
- medium Data Exfiltration · line 175 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 | $0.00097 | $0.02745 |
| Opus 5.5 | $0.00039 | $0.01098 |
| Sonnet 5.5 | $0.00019 | $0.00549 |
| Haiku 4.5 | $0.00010 | $0.00275 |
Grade A, and why
offensive-jwt scanned grade A with 1 finding 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 1mo 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -H "Authorization: Bearer <api_key>" https://api.target/resource Copies of this mod
1 near-identical copy found in the catalogue:
- offensive-jwt — 92% identical, 40 lines differ
How it starts
The opening of the file, as written. The whole thing — 275 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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
RSAandHMAC(confusion attack) - Weak or guessable HMAC secret (brute-forceable)
kid,jku,jwk,x5uheader parameters accepted without validation- Expired or tampered tokens accepted by server
- Sensitive data stored unencrypted in payload
Useful tool: 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:
- JWS/JWE confusion: server accepts encrypted token (JWE) where signed (JWS) is expected, or fails open on unexpected
typ/cty - JWKS retrieval: SSRF via
jku/x5u, insecure TLS, poisoned key caching,kidcollisions - Token binding (DPoP, mTLS): incorrectly implemented allows replay from other clients
Hunt: Identifying JWT Usage
- Check
Authorization: Bearer <token>headers in all requests - Look for cookies containing JWT structures (
eyJ...) - Examine browser local/session storage
- Decode the token at jwt.io or via BurpSuite JWT extension — inspect claims and header parameters
- Note any
kid,jku,jwk,x5ufields in the header — these are attack surfaces
Vulnerability Map
JWT Vulnerabilities
├── Algorithm Bypass
│ ├── alg:none attack
│ └── RS256→HS256 confusion (public key as HMAC secret)
├── Weak Secret Key → Brute force
├── kid Parameter Injection
│ ├── SQL injection via kid
│ └── Path traversal via kid
├── Header Injection
│ ├── jwk (inline fake key)
│ ├── jku/x5u (remote attacker-controlled JWKS)
│ └── JWKS cache poisoning
└── Missing / Broken Validation
├── No signature check
├── Expired tokens accepted
└── iss/aud/exp not validated
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.
- 1mo ago First seen · 275 lines · 97 tokens per session scan A f4062ca66c12
offensive-jwt is a skill published in the GitHub repository SnailSploit/Claude-Red (7,620 stars, last pushed 8d ago), licensed MIT. It adds 97 tokens to every session and 2,745 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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