securing-ai-systems

securing-ai-systems is a skill for Claude Code from trilwu/secskills. It costs 85 tokens per session (2,591 once invoked), scanned A, original, MIT.

A security assessment guide for applications that use large language models, AI agents, tools, memory, or retrieval systems. It covers attacks where untrusted text changes instructions, causes unsafe tool use, or exposes stored data.

In plain words
What is it for?
Use it to review chatbots, copilots, agents, MCP servers, plugins, and RAG pipelines; assess prompt injection, excessive permissions, data leakage, memory poisoning, and model or dependency supply-chain risks.
Why use it?
AI systems can treat data as instructions, so ordinary checks may not stop prompt injection or poisoned content. The guide helps identify risks in the model, tools, memory, retrieved documents, and supporting software.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is modelscan -p ./models/.

Part of the secskills-core plugin — 30 skills shipped together

Good fit Use it to review chatbots, copilots, agents, MCP servers, plugins, and RAG pipelines; assess prompt injection, excessive permissions, data leakage, memory poisoning, and model or dependency supply-chain risks.

Compare 6 skills from other repositories ↓
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/trilwu/secskills
agentmods
npx agentmods add skills/trilwu/secskills/securing-ai-systems

Made for: Claude Code.

Or install secskills-core, the plugin that ships this one along with the rest of its 30 skills.

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 securing-ai-systems

README.md
[![agentmods](https://agentmods.dev/badge/skills/trilwu/secskills/securing-ai-systems/github.svg)](https://agentmods.dev/skills/trilwu/secskills/securing-ai-systems)
Your own site
<a href="https://agentmods.dev/skills/trilwu/secskills/securing-ai-systems"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/securing-ai-systems/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 securing-ai-systems

Your own site · 80×15
<a href="https://agentmods.dev/skills/trilwu/secskills/securing-ai-systems"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/securing-ai-systems.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 85 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,591 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 172
    Skill grants unrestricted tool access without appropriate constraints. An agent with unfettered tool access can perform arbitrary actions including file modification, network requests, and code execution.
    Fix: Restrict tool access to only the tools required for the skill's stated purpose. Use an explicit allowlist rather than granting blanket access.
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 $0.00085 $0.02591
Opus 5 $0.00043 $0.01295
Sonnet 5 $0.00017 $0.00518
Haiku 4.5 $0.00009 $0.00259

Measured 9d ago against content hash 053891fb6ff7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

securing-ai-systems scanned grade A with 1 finding 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -sL "https://defuddle.md/<url>" # scheme in the path is optional
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

secskills-core/skills/securing-ai-systems/SKILL.md · 257 lines

How it starts

The opening of the file, as written. The whole thing — 257 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Securing AI Systems

LLM applications break the assumption every other security control is built on: that instructions and data are separable. In an LLM, data is instructions. Every design that reads untrusted content and then acts has to be evaluated with that in mind, and no amount of prompt engineering fixes it.

When to Use

  • Security review of an LLM-backed feature, chatbot, or copilot
  • Threat modeling an agentic system: tools, autonomy, memory, multi-agent
  • Reviewing an MCP server, tool definition, or plugin surface
  • Assessing a RAG pipeline for data leakage and poisoning
  • Evaluating model, dataset, and dependency supply chain
  • Red teaming an AI system with authorization

When NOT to Use

  • Conventional web/API vulnerabilities in the surrounding app — use auditing-code-for-vulnerabilities, testing-web-applications, testing-apis. Most real AI-app breaches are still ordinary IDOR and SSRF.
  • Building jailbreaks or attacks against third-party models you do not own or have authorization to test — out of scope
  • Model safety alignment research — different discipline

Route to a Depth Skill

Focus Skill
Auditing an MCP server specifically — tool-definition injection, per-tool authorization, transport security, resource exposure auditing-mcp-servers

The MCP review here is one part of a wider AI threat model; reach for auditing-mcp-servers when the server implementation itself is the target.

The Core Rule

Treat every model output as untrusted user input, and every input the model reads as potentially adversarial instructions.

From that single rule, most of the correct architecture follows: never route model output into a sink without the same validation you would apply to a form field, and never grant the model an authority the least trusted content it will read should not have.

The Lethal Trifecta

An agent is exposed to serious compromise when it has all three of:

  1. Access to private data (files, DB, internal APIs, user context)
  2. Exposure to untrusted content (web pages, email, tickets, PRs, docs)
  3. A way to communicate externally (HTTP, email, writes to a shared surface)

Read the full file on GitHub · 257 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. 9d ago First seen · 257 lines · 85 tokens per session scan A 053891fb6ff7

Subscribe to this mod's changes

securing-ai-systems is a skill published in the GitHub repository trilwu/secskills (137 stars, last pushed 4d ago), licensed MIT. It adds 85 tokens to every session and 2,591 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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