security-investigator: Skill for Claude Code

.github/skills/ca-policy-investigation/SKILL.md

ca-policy-investigation is a skill for Claude Code, Codex from SCStelz/security-investigator. It costs 104 tokens per session (3,368 once invoked), scanned A, original, MIT.

A security investigation tool for Conditional Access, Microsoft Entra’s rules for deciding whether sign-ins are allowed. It compares policy changes with sign-in failures to assess troubleshooting, bypass attempts, or misuse of admin rights.

In plain words
What is it for?
Use it to investigate Conditional Access changes, sign-in errors such as 53000 or 50074, possible policy bypasses, and suspicious administrator actions.
Why use it?
It helps determine whether an access problem was caused by a legitimate policy change or by someone weakening security controls.

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 →

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/ca-policy-investigation/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 ca-policy-investigation

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/scstelz/security-investigator/ca-policy-investigation"><img src="https://agentmods.dev/badge/skills/scstelz/security-investigator/ca-policy-investigation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,368 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: 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 240
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 $0.00104 $0.03368
Opus 5 $0.00052 $0.01684
Sonnet 5 $0.00021 $0.00674
Haiku 4.5 $0.00010 $0.00337

Measured 13d ago against content hash d3b7fb7ce88f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

ca-policy-investigation 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 13d 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/ca-policy-investigation/SKILL.md · 383 lines

How it starts

The opening of the file, as written. The whole thing — 383 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Conditional Access Policy Investigation - Instructions

Purpose

This skill investigates Conditional Access (CA) policy changes in correlation with sign-in failures to detect:

  • Legitimate troubleshooting (authorized policy changes to resolve access issues)
  • Security control bypass (unauthorized policy modifications to circumvent blocks)
  • Privilege abuse (users with admin rights weakening security controls)

The key distinction is whether policy changes were authorized and necessary vs self-service bypass of security controls.


📑 TABLE OF CONTENTS

  1. Critical Investigation Rules - Mandatory workflow steps
  2. Common Error Codes - Sign-in failure reference
  3. CA Policy States - Understanding policy modes
  4. 5-Step Investigation Workflow - KQL queries and analysis
  5. Real-World Example - Complete walkthrough
  6. Critical Mistakes - What NOT to do
  7. Security Recommendations - Remediation guidance

Critical Investigation Rules

When investigating sign-in failures (error codes 53000, 50074) with CA policy correlation:

⚠️ MANDATORY STEPS - DO NOT SKIP:

  1. Query ALL CA policy changes in chronological order (±2 days from failure time)
  2. Parse policy state transitions from the JSON (enabled → disabled → report-only)
  3. Compare failure timeline with policy change timeline
  4. Verify logical consistency: Ask "does this make sense?"

Key Questions to Answer:

  • Was the user blocked BEFORE the policy change?
  • Did the policy change resolve the block?
  • Who initiated the policy change? (same user = suspicious)
  • What was the business justification?

Common Error Codes

Error Code Description Typical Cause
53000 Device not compliant Device not enrolled in Intune or failing compliance checks
50074 Strong authentication required MFA not satisfied
50074 User must enroll in MFA MFA not configured for user
530032 Blocked by CA policy Generic CA policy block
65001 User consent required Application consent needed
53003 Access blocked by CA policy Explicit block condition met
70044 Session expired User needs to re-authenticate

Read the full file on GitHub · 383 lines

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. 13d ago First seen · 383 lines · 104 tokens per session scan A d3b7fb7ce88f

Subscribe to this mod's changes

ca-policy-investigation is a skill published in the GitHub repository SCStelz/security-investigator (245 stars, last pushed 4d ago), licensed MIT. It adds 104 tokens to every session and 3,368 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 2026-08-30.

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