owasp-llm-top10

owasp-llm-top10 is a skill for Claude Code from sigistry/marketplace. It costs 97 tokens per session (1,044 once invoked), scanned A, original, MIT.

A security review guide for applications built with large language models (LLMs), including the OWASP Top 10 risks for LLM applications. It connects risks such as prompt injection and unsafe tool use to code patterns and attacks to test.

In plain words
What is it for?
Use it to review prompts, retrieved documents, web content, tool outputs, capabilities, and data flows for injection, exfiltration, insecure output, and related LLM risks.
Why use it?
It helps developers recognize when untrusted text can influence an AI system's instructions or actions, leading to data leaks, unsafe tool calls, or other failures.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the llm-app-hardener plugin — 4 skills, 4 commands, 2 agents shipped together

Good fit Use it to review prompts, retrieved documents, web content, tool outputs, capabilities, and data flows for injection, exfiltration, insecure output, and related LLM risks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sigistry/marketplace/owasp-llm-top10
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add sigistry/marketplace --skill owasp-llm-top10
Clone the repo
git clone --depth 1 https://github.com/sigistry/marketplace

Made for: Claude Code.

Or install llm-app-hardener, the plugin that ships this one along with the rest of its 4 skills, 4 commands, 2 agents.

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 owasp-llm-top10

README.md
[![agentmods](https://agentmods.dev/badge/skills/sigistry/marketplace/owasp-llm-top10/github.svg)](https://agentmods.dev/skills/sigistry/marketplace/owasp-llm-top10)
Your own site
<a href="https://agentmods.dev/skills/sigistry/marketplace/owasp-llm-top10"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/owasp-llm-top10/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.

agentmods 80×15 button for owasp-llm-top10

Your own site · 80×15
<a href="https://agentmods.dev/skills/sigistry/marketplace/owasp-llm-top10"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/owasp-llm-top10.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,044 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.
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 $0.00097 $0.01044
Opus 5 $0.00048 $0.00522
Sonnet 5 $0.00019 $0.00209
Haiku 4.5 $0.00010 $0.00104

Measured 9d ago against content hash 5a9f9a42d212, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

owasp-llm-top10 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 9d 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.

plugins/llm-app-hardener/skills/owasp-llm-top10/SKILL.md · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

OWASP LLM Top 10

Purpose

Provide a standardized, code-level lens for auditing LLM applications against the OWASP Top 10 for LLM Applications, so a security review of prompt construction and tool wiring is consistent and grounded in the source, not hand-waved. The recurring, highest-impact failure is LLM01 prompt injection: untrusted content (user text, retrieved documents, tool outputs, fetched web/email) is concatenated into a prompt and then read as instructions, driving the model, and any tool it can call, to do the attacker's bidding. This skill maps each risk to the code pattern that causes it, the mitigation, and a concrete attack to test with.

The core mental model

An LLM has no reliable boundary between "instructions" and "data." Everything in the context window is a candidate instruction. Security follows from three questions asked at every call site:

  1. Provenance: is this text trusted (developer-authored) or untrusted (from a user, a document, a tool result, the web)?
  2. Capability: what tools can the model call, and what can each tool do (read secrets? send data? mutate state?)?
  3. Reachability: can untrusted text change the instructions in a way that reaches a dangerous capability?

If untrusted text and a dangerous capability meet with nothing between them, you have an exploitable path.

Risk-to-signal quick map

ID Risk Code-level signal
LLM01 Prompt injection Untrusted input interpolated into a prompt with no delimiting/labeling; RAG docs or tool outputs re-fed unfenced
LLM02 Insecure output handling Model output → HTML/SQL/shell/redirect/URL with no filtering
LLM03 Training-data / data poisoning Untrusted content ingested into the index or fine-tune set without provenance checks
LLM04 Model denial of service Unbounded output/context, recursive agent loops, no max_tokens/step limit
LLM05 Supply-chain Unpinned models, untrusted plugins/tools, unverified third-party prompts
LLM06 Sensitive information disclosure Secrets/PII in the prompt or reachable by a tool; model can echo them out
LLM07 Insecure plugin/tool design Over-broad tool (shell, arbitrary HTTP), no input validation, no least privilege
LLM08 Excessive agency Model can take irreversible/high-impact actions with no confirmation gate
LLM09 Overreliance App trusts model output as fact with no verification/grounding
LLM10 Model theft Unprotected model endpoints, prompt/weight leakage

Read the full file on GitHub · 47 lines

Files

What ships with it

2 files 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. 9d ago First seen · 47 lines · 97 tokens per session scan A 5a9f9a42d212

Subscribe to this mod's changes

owasp-llm-top10 is a skill published in the GitHub repository sigistry/marketplace (3 stars, last pushed today), licensed MIT. It adds 97 tokens to every session and 1,044 once invoked, about $0.0005 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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