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ClaudSkills / Security / web-security

Offensive API Abuse

Category: Security  ·  Sub-category: web-security  ·  Last updated:
Advanced API exploitation methodology focused on business logic abuse and sophisticated attack patterns that bypass traditional security controls. Covers business logic bypass through API call chaining and workflow manipulation. Addresses GraphQL-specific attacks including batching for credential brute-force, query depth exploitation, and introspection abuse. Includes pagination exploitation for data exfiltration, webhook hijacking for SSRF and data interception, and resource exhaustion through algorithmic complexity attacks. Covers race conditions in API transactions using parallel request techniques. Provides comprehensive JWT manipulation including algorithm confusion, kid injection, jku/x5u abuse, and claim tampering. Details API key leakage detection across source repositories, client-side code, and error messages. Covers undocumented endpoint discovery through predictable naming, debug routes, and source map analysis. Tooling includes Arjun, ParamSpider, jwt_tool, and GraphQL Voyager. Designed for authorized penetration testers targeting business logic layers that automated scanners miss.
Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

You are conducting authorized security assessments targeting the business logic layer of API-driven applications. Traditional vulnerability scanners miss the attack patterns in this skill because they require understanding of application workflows, state transitions, and trust relationships between API endpoints. Your goal is to identify vulnerabilities that allow financial manipulation, data exfiltration through legitimate channels, privilege escalation via workflow abuse, and service disruption through logic-layer attacks.

What this skill does

Offensive API Abuse 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-abuse/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Offensive API Abuse 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-abuse
curl -L https://claudskills.com/skills/offensive-api-abuse/SKILL.md \
  -o ~/.claude/skills/offensive-api-abuse/SKILL.md

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

Skills live at ~/.claude/skills/offensive-api-abuse/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\offensive-api-abuse\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 Abuse Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/offensive-api-abuse/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Offensive API Abuse skill do?
Advanced API exploitation methodology focused on business logic abuse and sophisticated attack patterns that bypass traditional security controls. Covers business logic bypass through API call chaining and workflow manipulation. Addresses GraphQL-specific attacks including batching for credential brute-force, query depth exploitation, and introspection abuse. Includes pagination exploitation for data exfiltration, webhook hijacking for SSRF and data interception, and resource exhaustion through algorithmic complexity attacks. Covers race conditions in API transactions using parallel request techniques. Provides comprehensive JWT manipulation including algorithm confusion, kid injection, jku/x5u abuse, and claim tampering. Details API key leakage detection across source repositories, client-side code, and error messages. Covers undocumented endpoint discovery through predictable naming, debug routes, and source map analysis. Tooling includes Arjun, ParamSpider, jwt_tool, and GraphQL Voyager. Designed for authorized penetration testers targeting business logic layers that automated scanners miss.
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 Abuse skill?
Use Offensive API Abuse 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 Abuse" 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 Abuse 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 Abuse 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 Abuse [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/offensive-api-abuse/
BibTeX
@misc{offensive-api-abuse-2026,
  author    = {SnailSploit},
  title     = {Offensive API Abuse [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/offensive-api-abuse/}
}

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Security scan

Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 3 of 10 categories (filesystem, network, obfuscation), 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.

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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
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