security-investigator: Skill for Claude Code

.github/skills/ai-agent-posture/SKILL.md

ai-agent-posture is a skill for Claude Code, Codex from SCStelz/security-investigator. It costs 222 tokens per session (19,901 once invoked), scanned A, original, MIT.

A security audit for AI agents used with Microsoft and third-party platforms. It examines agents that can access company data, send email, call outside services, or use MCP tools.

In plain words
What is it for?
Use it to report on an organization's AI-agent inventory and security posture across Copilot Studio, Microsoft 365 Copilot, Microsoft Foundry, and third-party agents, including broadly accessible agents and XPIA risks.
Why use it?
It helps identify risky settings such as missing login protection, overly broad access, agent-controlled email, and exposed credentials. It uses the AgentsInfo table in Microsoft Defender XDR Advanced Hunting.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

This is SCStelz/security-investigator's own configuration. It tells Claude Code and Codex how to work on security-investigator itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything security-investigator configures →

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is **Full enrichment query library:** [`queries/cloud/entra_agent_identity.md`](../../../queries/cloud/entra_agent_identity.md) — Queries 1–6, the validated cross-.

Reuse

Borrowing it

Nothing to install: this file belongs to SCStelz/security-investigator. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/SCStelz/security-investigator/main/.github/skills/ai-agent-posture/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/SCStelz/security-investigator

Made for: Claude Code, Codex.

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 ai-agent-posture

README.md
[![agentmods](https://agentmods.dev/badge/skills/scstelz/security-investigator/ai-agent-posture/github.svg)](https://agentmods.dev/skills/scstelz/security-investigator/ai-agent-posture)
Your own site
<a href="https://agentmods.dev/skills/scstelz/security-investigator/ai-agent-posture"><img src="https://agentmods.dev/badge/skills/scstelz/security-investigator/ai-agent-posture/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 ai-agent-posture

Your own site · 80×15
<a href="https://agentmods.dev/skills/scstelz/security-investigator/ai-agent-posture"><img src="https://agentmods.dev/badge/skills/scstelz/security-investigator/ai-agent-posture.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 222 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 19,901 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, 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 500
    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.
  • medium Agent Snooping · line 1256
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 $0.00222 $0.19901
Opus 5 $0.00111 $0.09950
Sonnet 5 $0.00044 $0.03980
Haiku 4.5 $0.00022 $0.01990

Measured 12d ago against content hash 5017394d3b30, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

ai-agent-posture 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 12d 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.

.github/skills/ai-agent-posture/SKILL.md · 1,262 lines

How it starts

The opening of the file, as written. The whole thing — 1,262 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AI Agent Security Posture — Instructions

Purpose

This skill audits the security posture of AI agents (Copilot Studio, Microsoft 365 Copilot / Agent Builder, Microsoft Foundry, and third-party platforms) across your organization using the AgentsInfo table in Microsoft Defender XDR Advanced Hunting.

🔄 Table migration (AIAgentsInfo → AgentsInfo): This skill was migrated from the deprecated AIAgentsInfo table to the unified multi-platform AgentsInfo table. AIAgentsInfo remains queryable until July 1, 2026, but it is Copilot Studio-only and uses a different schema. All queries in this skill target AgentsInfo. The new table is a different data model, not a rename — see Table Schema Reference and Known Pitfalls for the differences that shaped these queries.

AI agents are autonomous or semi-autonomous applications that can access organizational data, send emails, call external APIs, and use MCP tools. Misconfigured agents — missing authentication, overly broad access, AI-controlled email sending, hard-coded credentials — represent a growing attack surface. This skill systematically evaluates that surface.

What this skill covers:

Domain Key Questions Answered
🔍 Agent Inventory How many agents exist? What's their status, platform, environment?
🔐 Access Posture Which agents are broadly accessible (allowForAllUsers)? How are agents shared (appType: lob/shared)?
🛠️ Tools & MCP Which agents have MCP tools? What operations can they perform?
📚 Knowledge Sources What data sources are agents connected to?
📧 XPIA Email Risk Which agents can send email (data exfil precondition)?
🔑 Credential Exposure Are credentials hard-coded in agent instructions or connector metadata?
🌐 External Endpoint Risk What external hosts do agent connectors reach? Any insecure schemes or non-standard ports?
👥 Creator Governance Who creates agents? Is there naming hygiene? Abandoned agents?

Read the full file on GitHub · 1,262 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. 12d ago First seen · 1,262 lines · 222 tokens per session scan A 5017394d3b30

Subscribe to this mod's changes

ai-agent-posture is a skill published in the GitHub repository SCStelz/security-investigator (245 stars, last pushed 4d ago), licensed MIT. It adds 222 tokens to every session and 19,901 once invoked, about $0.0011 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 2026-08-30.

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