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.
curl -O https://raw.githubusercontent.com/SCStelz/security-investigator/main/.github/skills/scope-drift-detection/spn/SKILL.mdgit clone --depth 1 https://github.com/SCStelz/security-investigatorWrote 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.
[](https://agentmods.dev/skills/scstelz/security-investigator/spn)<a href="https://agentmods.dev/skills/scstelz/security-investigator/spn"><img src="https://agentmods.dev/badge/skills/scstelz/security-investigator/spn/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.
<a href="https://agentmods.dev/skills/scstelz/security-investigator/spn"><img src="https://agentmods.dev/badge/skills/scstelz/security-investigator/spn.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
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 104 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.
- medium Agent Snooping · line 715 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.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00127 | $0.09392 |
| Opus 5 | $0.00063 | $0.04696 |
| Sonnet 5 | $0.00025 | $0.01878 |
| Haiku 4.5 | $0.00013 | $0.00939 |
Grade A, and why
scope-drift-detection-spn 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 721 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Service Principal Scope Drift Detection — Instructions
Purpose
Credit: The scope drift detection concept for service principals was inspired by Iftekhar Hussain's article The Agentic SOC Era: How Sentinel MCP Enables Autonomous Security Reasoning (Feb 2026), which demonstrated multi-source correlation across AADServicePrincipalSignInLogs, AuditLogs, and SecurityAlert to build 90-day behavioral baselines and surface drift via weighted scoring.
This skill detects scope drift — the gradual, often imperceptible expansion of access or behavior beyond an established baseline — in Entra ID service principals. Unlike sudden compromise (which triggers alerts), scope drift is a slow-burn pattern that evades threshold-based detections.
Entity Type: Service Principal
| Identifier | Primary Table(s) | Use Case |
|---|---|---|
| ServicePrincipalName / ServicePrincipalId | AADServicePrincipalSignInLogs |
App registrations, automation accounts, managed identities |
What this skill detects:
- Volume spikes in sign-in activity relative to historical baseline
- New target resources (APIs, services) not previously accessed
- New source IP addresses or geographic locations
- Increased failure rates indicating probing or misconfiguration
- Credential/permission changes correlated with behavioral shifts
- Security alerts involving the drifting entities
Related skills:
- User Scope Drift — for user accounts (UPNs)
- Device Scope Drift — for endpoints/devices
📑 TABLE OF CONTENTS
- Critical Workflow Rules - Start here!
- Output Modes - Inline chat vs. Markdown file
- Quick Start - 7-step investigation pattern
- Drift Score Formula - Weighted composite scoring (5 dimensions)
- Execution Workflow - Complete 4-phase process
- Sample KQL Queries - Validated query patterns (Queries 1-4)
- Report Template - Output format specification
- Known Pitfalls - Edge cases and false positives
- Error Handling - Troubleshooting guide
- SVG Dashboard Generation - Visual dashboard from report
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.
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.
- 10d ago First seen · 721 lines · 127 tokens per session scan A b078a5d36495
scope-drift-detection-spn is a skill published in the GitHub repository SCStelz/security-investigator (245 stars, last pushed 2d ago), licensed MIT. It adds 127 tokens to every session and 9,392 once invoked, about $0.0006 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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