waf-bypass-techniques

waf-bypass-techniques is a skill for Claude Code, Codex from yaklang/hack-skills. It costs 57 tokens per session (3,075 once invoked), scanned A, original, MIT.

A security testing guide for checking how web application firewalls handle altered versions of SQL injection, cross-site scripting, and remote-code-execution inputs.

In plain words
What is it for?
Use it during authorized tests to identify a firewall, choose an evasion approach, and assess whether filtering can be bypassed.
Why use it?
It helps explain why a firewall may block obvious attack tests while missing requests changed through encoding, HTTP behavior, or duplicate parameters.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is └── See ../request-smuggling/SKILL.md.

Good fit Use it during authorized tests to identify a firewall, choose an evasion approach, and assess whether filtering can be bypassed.

Compare 6 skills from other repositories ↓
About the project

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.

yaklang/hack-skills · 2,143 stars · on GitHub

Install

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.

Clone the repo
git clone --depth 1 https://github.com/yaklang/hack-skills
agentmods
npx agentmods add skills/yaklang/hack-skills/waf-bypass-techniques

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for waf-bypass-techniques

README.md
[![agentmods](https://agentmods.dev/badge/skills/yaklang/hack-skills/waf-bypass-techniques/github.svg)](https://agentmods.dev/skills/yaklang/hack-skills/waf-bypass-techniques)
Your own site
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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.

agentmods 80×15 button for waf-bypass-techniques

Your own site · 80×15
<a href="https://agentmods.dev/skills/yaklang/hack-skills/waf-bypass-techniques"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/waf-bypass-techniques.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,075 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 30 Apr 2026
  • Snyk fail 30 Apr 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00057 $0.03075
Opus 5 $0.00028 $0.01537
Sonnet 5 $0.00011 $0.00615
Haiku 4.5 $0.00006 $0.00308

Measured 6d ago against content hash 28544c354da1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

waf-bypass-techniques scanned grade A with 0 findings 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 6d 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

3 near-identical copies found in the catalogue:

skills/waf-bypass-techniques/SKILL.md · 291 lines

How it starts

The opening of the file, as written. The whole thing — 291 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: WAF Bypass Techniques — Evasion Playbook

AI LOAD INSTRUCTION: Covers WAF identification, generic bypass categories (encoding, protocol abuse, HTTP/2, parameter pollution), and a decision tree. For product-specific bypasses (Cloudflare, AWS WAF, ModSecurity, Akamai, etc.), load WAF_PRODUCT_MATRIX.md. Base models often suggest basic encoding but miss protocol-level bypasses and WAF behavioral quirks.

  • sqli-sql-injection for payloads to deliver after bypassing WAF
  • xss-cross-site-scripting for XSS payloads that need WAF evasion
  • request-smuggling when smuggling can route requests around WAF entirely
  • http-parameter-pollution HPP is itself a WAF bypass primitive
  • csp-bypass-advanced when WAF blocks inline scripts but CSP bypass is available
  • ghost-bits-cast-attack Java backends only — when every encoding trick above is blocked, use Ghost Bits: Java's 16-bit char to 8-bit byte narrowing produces 255 Unicode bypass variants per dangerous ASCII byte; re-enables WAF-patched CVEs in Tomcat, Spring, Jetty, Jackson, Fastjson, BCEL, and more

Product-Specific Reference

Load WAF_PRODUCT_MATRIX.md when you need per-product bypass techniques for Cloudflare, AWS WAF, ModSecurity CRS, Akamai, Imperva, F5 BIG-IP, or Sucuri.


1. PHASE 0 — IDENTIFY THE WAF

Before bypassing, know what you're fighting.

1.1 Tools

Tool Usage
wafw00f target.com Fingerprint WAF vendor from response headers/behavior
nmap --script=http-waf-detect NSE script for WAF detection
Manual header inspection Server, X-CDN, X-Cache, cf-ray (Cloudflare), x-sucuri-id, x-akamai-*

1.2 Behavioral Fingerprinting

1. Send benign request → record baseline response (status, headers, body size)
2. Send obvious attack: /?q=<script>alert(1)</script>
3. Compare: 403? Custom block page? Redirect? Connection reset?
4. Block page content reveals WAF: "Cloudflare", "Access Denied (Imperva)", "ModSecurity"
5. If transparent proxy: check response time difference (WAF adds latency)

Read the full file on GitHub · 291 lines

Files

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.

Changes

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.

  1. 6d ago First seen · 291 lines · 57 tokens per session scan A 28544c354da1

Subscribe to this mod's changes

waf-bypass-techniques is a skill published in the GitHub repository yaklang/hack-skills (2,143 stars, last pushed 2mo ago), licensed MIT. It adds 57 tokens to every session and 3,075 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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