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/ShulkwiSEC/bb-hugenpx agentmods add skills/shulkwisec/bb-huge/jwt-labsWrote 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/shulkwisec/bb-huge/jwt-labs)<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/jwt-labs"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/jwt-labs/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/shulkwisec/bb-huge/jwt-labs"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/jwt-labs.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00026 | $0.01146 |
| Opus 5 | $0.00013 | $0.00573 |
| Sonnet 5 | $0.00005 | $0.00229 |
| Haiku 4.5 | $0.00003 | $0.00115 |
Grade A, and why
JWT Authentication — Complete Deep Dive 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 7d 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.
tools: [burp-suite, curl, sqlmap, ffuf, python, hashcat, ysoserial] Copies of this mod
1 near-identical copy found in the catalogue:
- JWT Authentication — Complete Deep Dive — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.
JWT Authentication — Complete Deep Dive
Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. 🟢 Apprentice 🟡 Practitioner 🔴 Expert
When to Use
- BSCP certification prep
- Real-world bug bounty hunting
- Building exploitation chains
- Understanding bypass techniques
Prerequisites
- Burp Suite Professional
- Burp Collaborator / interactsh
- Browser with proxy configured
Workflow
Phase 1: Reconnaissance
- Identify input vectors, parameters, and application behavior.
Phase 2: Exploitation
- Apply standard lab payloads.
Phase 3: Zero-Day Escalation
- Fuzz filters, bypass WAFs, and chain with other vulns.
Lab Playbooks
Lab 1: Unverified signature 🟢 APPRENTICE
Decode JWT, change sub to administrator, re-encode (no signing needed — server doesn't verify).
Lab 2: Flawed signature verification 🟢 APPRENTICE
Remove the signature portion entirely. Server checks signature only if present.
Lab 3: Weak signing key 🟡 PRACTITIONER
hashcat -a 0 -m 16500 JWT_TOKEN /usr/share/wordlists/rockyou.txt
Crack HS256 secret → forge any token.
Lab 4: jwk header injection 🟡 PRACTITIONER
Generate RSA key, sign token with it, embed public key in jwk header parameter. Server uses embedded key to verify.
Lab 5: jku header injection 🟡 PRACTITIONER
Host JWK Set on exploit server, set jku header to your URL. Server fetches your keys.
Lab 6: kid header path traversal 🟡 PRACTITIONER
{"kid":"../../../dev/null","alg":"HS256"}
Sign with empty string (content of /dev/null). Server uses file content as verification key.
Lab 7: Algorithm confusion 🔴 EXPERT
Get server's RSA public key → change alg to HS256 → sign with public key as HMAC secret.
openssl s_client -connect TARGET:443 | openssl x509 -pubkey -noout > public.pem
# Use public.pem as HS256 key to sign forged JWT
Lab 8: Algorithm confusion no exposed key 🔴 EXPERT
Get two valid JWTs → derive RSA public key using rsa_sign2n tool → then do alg confusion attack.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 7d ago First seen · 134 lines · 26 tokens per session scan A f5ee60e4d956
JWT Authentication — Complete Deep Dive is a skill published in the GitHub repository ShulkwiSEC/bb-huge (22 stars, last pushed 2mo ago), licensed MIT. It adds 26 tokens to every session and 1,146 once invoked, about $0.0001 per session on Opus 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 2026-09-03.
Other skills, from other repositories
HTTP Request Smuggling — Complete Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.
Business Logic Vulnerabilities — Complete Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.
Server-Side Template Injection — Complete Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.
Race Conditions — Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.
SQL Injection — Complete Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.
Cross-Site Scripting (XSS) — Complete Deep Dive
Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques.