Claude Code Skills·Claude Skills·The open SKILL.md registry for Claude
ClaudSkills / Security / web-security

Harden Waf

Category: Security  ·  Sub-category: web-security  ·  Last updated:
cloud:cloudflare
Defensive methodology for web application firewall evasion, where an attacker wraps an injection payload (SQLi, XSS, RCE, path traversal) in encodings the WAF misses but the backend still decodes, or abuses chunked Transfer-Encoding and duplicate length headers to desync the front-end filter from the origin (HTTP request smuggling). Maps to MITRE ATT&CK T1190 and T1027. Keys off WAF logs (AWS WAF, Azure WAF, Cloudflare, OWASP CRS / ModSecurity / Coraza, F5 ASM), CDN and reverse-proxy access logs, and backend error logs. Gives a normalization-first detection approach, a WAF-miss and desync hunt, and rule-tuning and protocol-strictness hardening. Use when hardening or tuning a WAF, closing encoding and double-encoding evasion gaps, defending against request-smuggling desync, raising OWASP CRS paranoia level, triaging requests that pass the WAF but error at the backend, or hunting for signature-evasion against a public web app.
Security AStatic scan found no risk patternsHow grading works ›

What this skill does

Harden Waf is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/harden-waf/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when hardening or tuning a WAF, closing encoding and double-encoding evasion gaps, defending against request-smuggling desync, raising OWASP CRS paranoia level, triaging requests that pass the WAF but error at the backend, or hunting for signature-evasion against a public web app.

Who uses this skill

The Harden Waf Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/harden-waf
curl -L https://claudskills.com/skills/harden-waf/SKILL.md \
  -o ~/.claude/skills/harden-waf/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/harden-waf/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/harden-waf/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\harden-waf\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Harden Waf Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/harden-waf/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Harden Waf skill do?
Defensive methodology for web application firewall evasion, where an attacker wraps an injection payload (SQLi, XSS, RCE, path traversal) in encodings the WAF misses but the backend still decodes, or abuses chunked Transfer-Encoding and duplicate length headers to desync the front-end filter from the origin (HTTP request smuggling). Maps to MITRE ATT&CK T1190 and T1027. Keys off WAF logs (AWS WAF, Azure WAF, Cloudflare, OWASP CRS / ModSecurity / Coraza, F5 ASM), CDN and reverse-proxy access logs, and backend error logs. Gives a normalization-first detection approach, a WAF-miss and desync hunt, and rule-tuning and protocol-strictness hardening. Use when hardening or tuning a WAF, closing encoding and double-encoding evasion gaps, defending against request-smuggling desync, raising OWASP CRS paranoia level, triaging requests that pass the WAF but error at the backend, or hunting for signature-evasion against a public web app.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Harden Waf skill?
Use Harden Waf when your Claude Code task falls under the Security category — specifically in the web security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Harden Waf" or describe the task and let Claude pick). Browse related skills at /category/security/.
What is a Claude Code skill and how does the Harden Waf skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Harden Waf is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
umbrasec-labs. (2026). Harden Waf [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/harden-waf/
BibTeX
@misc{harden-waf-2026,
  author    = {umbrasec-labs},
  title     = {Harden Waf [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/harden-waf/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge
[![ClaudSkills](https://claudskills.com/badge/harden-waf.svg)](https://claudskills.com/skills/harden-waf/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)
<script>
<script src="https://claudskills.com/embed/harden-waf.js" async></script>
<iframe>
<iframe src="https://claudskills.com/embed/harden-waf.html" width="100%" height="160" frameborder="0" loading="lazy" title="ClaudSkills: Harden Waf"></iframe>

Security scan

Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/harden-waf/#security)

Free. No spam. Unsubscribe in one click.

More Security skills

Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills
Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills.  ·  What's New  ·  Install guide  ·  About  ·  llms.txt

Part of Acreator Store — Adam Lankamer's AI tools: PerfectStudio · Ucaption · UTagger · AutoXPoster · TestYourSkills · AutomationFlows · Au Naturel · Telegram @acreatorstore

Categories

Use cases

Popular tags

Learn

Site