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.
npx skills add Liberty91LTD/cti-skills --skill sigma-writinggit clone --depth 1 https://github.com/Liberty91LTD/cti-skillsWrote 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/liberty91ltd/cti-skills/sigma-writing)<a href="https://agentmods.dev/skills/liberty91ltd/cti-skills/sigma-writing"><img src="https://agentmods.dev/badge/skills/liberty91ltd/cti-skills/sigma-writing/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/liberty91ltd/cti-skills/sigma-writing"><img src="https://agentmods.dev/badge/skills/liberty91ltd/cti-skills/sigma-writing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00052 | $0.01274 |
| Opus 5.5 | $0.00021 | $0.00510 |
| Sonnet 5.5 | $0.00010 | $0.00255 |
| Haiku 4.5 | $0.00005 | $0.00127 |
Grade A, and why
sigma-writing 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 2mo 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 — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SIGMA Rule Writing Guide
SIGMA rules are vendor-agnostic detection rules written in YAML. They can be converted to platform-specific query languages (Splunk SPL, Elastic KQL, Microsoft Sentinel KQL, etc.).
Rule Structure
title: Descriptive title of the detection
id: <UUID> # Generate a unique UUID
status: experimental|test|stable
description: >
Detailed description of what this rule detects and why.
references:
- https://reference-url.com # Source intelligence, blog posts, CVE
author: CTI Platform
date: YYYY/MM/DD
modified: YYYY/MM/DD
tags:
- attack.initial_access # ATT&CK tactic (lowercase, dots)
- attack.t1566.001 # ATT&CK technique
- cve.2024.12345 # CVE if applicable
logsource:
category: process_creation # Log category
product: windows # OS/product
service: # Optional: specific service
detection:
selection:
FieldName|modifier:
- 'value1'
- 'value2'
filter_known_good:
FieldName: 'legitimate_value'
condition: selection and not filter_known_good
falsepositives:
- Description of known false positive scenario
level: critical|high|medium|low|informational
Log Source Categories
| Category | Description | Common fields |
|---|---|---|
process_creation |
New process started | Image, CommandLine, ParentImage, User |
network_connection |
Network connection initiated | DestinationIp, DestinationPort, SourceIp |
file_event |
File created/modified/deleted | TargetFilename, Image |
registry_event |
Registry key/value change | TargetObject, Details |
dns_query |
DNS resolution | QueryName, QueryType |
image_load |
DLL/module loaded | ImageLoaded, Image |
pipe_created |
Named pipe created | PipeName |
ps_script |
PowerShell script execution | ScriptBlockText |
webserver |
Web server access logs | cs-uri-query, c-ip |
firewall |
Firewall logs | src-ip, dst-ip, dst-port, action |
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.
- 2mo ago First seen · 145 lines · 52 tokens per session scan A 110d3d7fe1d2
sigma-writing is a skill published in the GitHub repository Liberty91LTD/cti-skills (36 stars, last pushed 4d ago), licensed MIT. It adds 52 tokens to every session and 1,274 once invoked, about $0.0002 per session on Opus 5.5. 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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