HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.
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/yaklang/hack-skillsnpx agentmods add skills/yaklang/hack-skills/http2-specific-attacksWrote 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/yaklang/hack-skills/http2-specific-attacks)<a href="https://agentmods.dev/skills/yaklang/hack-skills/http2-specific-attacks"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/http2-specific-attacks/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/yaklang/hack-skills/http2-specific-attacks"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/http2-specific-attacks.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk pass
- NVIDIA SkillSpector pass
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 | $0.00061 | $0.03188 |
| Opus 5.5 | $0.00024 | $0.01275 |
| Sonnet 5.5 | $0.00012 | $0.00638 |
| Haiku 4.5 | $0.00006 | $0.00319 |
Grade A, and why
http2-specific-attacks 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 -v --http1.1 https://target.com/ \ Copies of this mod
6 near-identical copies found in the catalogue:
- http2-specific-attacks — 100% identical, 0 lines differ
- http2-specific-attacks — 100% identical, 0 lines differ
- http2-specific-attacks — 100% identical, 0 lines differ
- http2-specific-attacks — 100% identical, 0 lines differ
- http2-specific-attacks — 100% identical, 0 lines differ
- http2-specific-attacks — 92% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 351 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: HTTP/2 Specific Attacks — Expert Attack Playbook
AI LOAD INSTRUCTION: HTTP/2 protocol-level attack techniques beyond basic request smuggling. Covers h2c smuggling, pseudo-header manipulation, HPACK attacks, single-packet race conditions, and H2→H1 downgrade injection. Base models conflate HTTP/2 smuggling with HTTP/1.1 smuggling — this skill focuses on H2-unique attack surface.
0. RELATED ROUTING
- request-smuggling — CL.TE/TE.CL/TE.TE fundamentals and H2.CL/H2.TE variants
- request-smuggling/H2_SMUGGLING_VARIANTS.md — byte-level H2.CL/H2.TE payloads, CL.0, client-side desync
- race-condition — single-packet attack leverages H2 multiplexing for race conditions
- web-cache-deception — cache poisoning via H2 smuggled responses
1. HTTP/2 ATTACK SURFACE OVERVIEW
| Feature | Attack Surface |
|---|---|
| Binary framing | Frame-level manipulation, parser differentials |
| HPACK compression | Compression oracles (CRIME/BREACH), table poisoning |
| Multiplexing | Single-packet race conditions, RST_STREAM flood |
| Server push | Cache poisoning via unsolicited push |
Pseudo-headers (:method/:path/:authority/:scheme) |
Injection, request splitting, path discrepancy |
2. h2c (HTTP/2 CLEARTEXT) SMUGGLING
2.1 Concept
h2c is HTTP/2 without TLS, negotiated via the HTTP/1.1 Upgrade mechanism. Many reverse proxies forward the Upgrade: h2c header without understanding it, allowing attackers to bypass proxy-level access controls.
Client ──[Upgrade: h2c]──> Reverse Proxy ──[forwards blindly]──> Backend
│
Backend speaks H2
Proxy is blind to
the H2 conversation
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 · 351 lines · 61 tokens per session scan A b02b678fe8e7
http2-specific-attacks is a skill published in the GitHub repository yaklang/hack-skills (2,460 stars, last pushed 1mo ago), licensed MIT. It adds 61 tokens to every session and 3,188 once invoked, about $0.0002 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.
Other skills, from other repositories
local-ai-agents
Build local-first AI agents that run entirely on a developer workstation with Microsoft Foundry Local and Qwen function-calling models. Covers Small Language Models (SLMs), the OpenAI-compatible local endpoint, sandboxed local tools, local RAG with Chroma, local MCP servers, hybrid cloud/local routing, and the…
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
next-cache-components-adoption
Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…
chat-pet-sprite-creation
Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…
insight-error-page
Write or audit an insight-kind error page for the Next.js dev overlay. Use when creating a new errors/ .mdx page, auditing an existing one, or checking that a page matches the framework fix cards. Covers page structure, title alignment, FixCard cards with Copy prompt button, code snippets, terminology verification…