Offensive API Security
Comprehensive API security testing methodology covering REST, gRPC, and WebSocket attack surfaces. Addresses the full OWASP API Security Top 10 2023 including BOLA/IDOR, broken authentication, excessive data exposure, rate limiting bypass, BFLA, mass assignment, SSRF, and security misconfiguration. Includes REST-specific attacks such as HTTP verb tampering, content-type switching, and parameter pollution. Covers gRPC exploitation through protobuf interception, reflection API enumeration, and metadata injection. Addresses WebSocket vulnerabilities including origin bypass, message injection, and cross-site WebSocket hijacking. Provides tooling guidance for Burp Suite, Postman, grpcurl, websocat, and mitmproxy. Each technique includes detection signatures and defensive indicators so you understand what artifacts your testing leaves behind. Designed for authorized penetration testing engagements against API-driven architectures.
Security AStatic scan found no risk patternsHow grading works ›
From the source SKILL.md
You are conducting authorized security assessments against API-driven applications. This skill covers REST, gRPC, and WebSocket attack surfaces with emphasis on the OWASP API Security Top 10 2023. Every technique assumes you have written authorization and a defined scope. Your goal is to identify vulnerabilities that allow unauthorized data access, privilege escalation, or service disruption through API-layer attacks.
What this skill does
Offensive API Security 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/offensive-api-security/ and loads when your prompt matches the skill's trigger.
Who uses this skill
The Offensive API Security 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 196,000+ 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/offensive-api-security
curl -L https://claudskills.com/skills/offensive-api-security/SKILL.md \
-o ~/.claude/skills/offensive-api-security/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/offensive-api-security/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/offensive-api-security/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\offensive-api-security\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.
Frequently asked questions
How do I install the Offensive API Security Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy
SKILL.md from the source repository to
~/.claude/skills/offensive-api-security/SKILL.md and restart Claude Code. Both flows are detailed at
claudskills.com/install/.
What does the Offensive API Security skill do?
Comprehensive API security testing methodology covering REST, gRPC, and WebSocket attack surfaces. Addresses the full OWASP API Security Top 10 2023 including BOLA/IDOR, broken authentication, excessive data exposure, rate limiting bypass, BFLA, mass assignment, SSRF, and security misconfiguration. Includes REST-specific attacks such as HTTP verb tampering, content-type switching, and parameter pollution. Covers gRPC exploitation through protobuf interception, reflection API enumeration, and metadata injection. Addresses WebSocket vulnerabilities including origin bypass, message injection, and cross-site WebSocket hijacking. Provides tooling guidance for Burp Suite, Postman, grpcurl, websocat, and mitmproxy. Each technique includes detection signatures and defensive indicators so you understand what artifacts your testing leaves behind. Designed for authorized penetration testing engagements against API-driven architectures.
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 Offensive API Security skill?
Use Offensive API Security 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 Offensive API Security" or describe the task and let Claude pick). Browse related skills at
/category/security/.
What is a Claude Code skill and how does the Offensive API Security 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. Offensive API Security 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
SnailSploit. (2026). Offensive API Security [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/offensive-api-security/
BibTeX
@misc{offensive-api-security-2026,
author = {SnailSploit},
title = {Offensive API Security [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/offensive-api-security/}
}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
[](https://claudskills.com/skills/offensive-api-security/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)
<script>
<script src="https://claudskills.com/embed/offensive-api-security.js" async></script>
<iframe>
<iframe src="https://claudskills.com/embed/offensive-api-security.html" width="100%" height="160" frameborder="0" loading="lazy" title="ClaudSkills: Offensive API Security"></iframe>
Security scan
Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.
The scan flagged 1 of 10 categories (network), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.
- ✓ Prompt injection
- ✓ Data exfiltration
- ✓ Supply chain
- ✓ Reverse shell
- ✓ Credentials
- ✓ Execution
- ✓ Filesystem
- ✓ Persistence
- ✓ Obfuscation
- ⚠ Network
Show this grade on your repo (click to copy):
[](https://claudskills.com/skills/offensive-api-security/#security)
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