SAVVYDFIR-MCP: Skill for Claude Code

.claude/skills/sigma-detection/SKILL.md

sigma-detection is a skill for Claude Code from kismatkunwar89/SAVVYDFIR-MCP. It costs 43 tokens per session (941 once invoked), scanned A, original, MIT.

A guide for finding unusual behavior in Windows forensic evidence and connecting findings to MITRE ATT&CK, a catalogue of common attack techniques.

In plain words
What is it for?
Use it when running Sigma scans, interpreting suspicious processes or network connections, and pivoting to injection, DLL, or file-hash checks.
Why use it?
It explains what the detection checks mean, how severity is assigned, and which investigation to perform next.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

This is kismatkunwar89/SAVVYDFIR-MCP's own configuration. It tells Claude Code how to work on SAVVYDFIR-MCP 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 SAVVYDFIR-MCP configures →

Reuse

Borrowing it

Nothing to install: this file belongs to kismatkunwar89/SAVVYDFIR-MCP. 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/kismatkunwar89/SAVVYDFIR-MCP/master/.claude/skills/sigma-detection/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/kismatkunwar89/SAVVYDFIR-MCP

Made for: Claude Code.

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 sigma-detection

README.md
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Your own site
<a href="https://agentmods.dev/skills/kismatkunwar89/savvydfir-mcp/sigma-detection"><img src="https://agentmods.dev/badge/skills/kismatkunwar89/savvydfir-mcp/sigma-detection/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 sigma-detection

Your own site · 80×15
<a href="https://agentmods.dev/skills/kismatkunwar89/savvydfir-mcp/sigma-detection"><img src="https://agentmods.dev/badge/skills/kismatkunwar89/savvydfir-mcp/sigma-detection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 941 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.
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 $0.00043 $0.00941
Opus 5 $0.00022 $0.00470
Sonnet 5 $0.00009 $0.00188
Haiku 4.5 $0.00004 $0.00094

Measured 11d ago against content hash 5e388adbf6a9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

sigma-detection 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 11d 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.

.claude/skills/sigma-detection/SKILL.md · 84 lines

How it starts

The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Sigma Detection - Universal Anomaly Detection Guide

How sigma_scan() Works

sigma_scan(case_id) reads ALL findings from the case state and runs 5 independent detectors. Each detector implements case-agnostic logic - no hardcoded IPs, usernames, or filenames.

Detector 1: Process Anomalies

What it checks:

  • svchost.exe not spawned by services.exe → masquerading (T1036.005)
  • System processes (smss, csrss, lsass, etc.) from non-System32 paths → masquerading
  • Orphan processes (PPID points to non-existent process) → possible DKOM or parent terminated

When it fires CRITICAL:

  • svchost wrong parent
  • System process wrong path

Pivot from hit:

  1. detect_injection(pid=FLAGGED_PID) - check for code injection
  2. list_dlls(pid=FLAGGED_PID) - check for suspicious DLLs
  3. Hash the binary: sha256sum <path>

Detector 2: Network Anomalies

What it checks:

  • System processes (svchost, lsass, etc.) with external (non-RFC1918) connections → C2
  • Outbound connections on non-standard ports (not 80/443/53/445/etc.) → covert channel
  • Listening sockets owned by unexpected processes

RFC1918 exclusion logic:

  • 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 are IGNORED (normal internal traffic)
  • Only external IPs trigger alerts

Pivot from hit:

  1. YARA scan memory for C2 signatures
  2. Check if the remote IP appears in other findings
  3. Timeline query around the connection timestamp

Detector 3: MFT Timestomping

What it checks:

  • $STANDARD_INFORMATION Created vs $FILE_NAME Created
  • If delta > 1 hour → timestomping detected (T1070.006)
  • SI timestamps are user-modifiable; FN timestamps require kernel access

Pivot from hit:

  1. Check prefetch for true first execution time
  2. Check amcache for SHA-1 hash of the binary
  3. run_analysis() on MFT CSV to find nearby file operations

Detector 4: EVTX High-Value Events

Auto-tagged events with ATT&CK mapping:

EventID Meaning Tactic Technique
4624 Logon success TA0001 T1078
4625 Logon failure TA0006 T1110
4648 Explicit logon TA0008 T1021
4672 Special privileges TA0004 T1134
4688 Process creation TA0002 T1059
4697 Service installed TA0003 T1543
4698 Scheduled task TA0003 T1053
4720 User created TA0003 T1136
7045 New service TA0003 T1543.003
1116 Defender detection TA0005 T1562

Read the full file on GitHub · 84 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. 11d ago First seen · 84 lines · 43 tokens per session scan A 5e388adbf6a9

Subscribe to this mod's changes

sigma-detection is a skill published in the GitHub repository kismatkunwar89/SAVVYDFIR-MCP (4 stars, last pushed 3mo ago), licensed MIT. It adds 43 tokens to every session and 941 once invoked, about $0.0002 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 2026-08-31.

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