#sigma

2 posts · Last used 11d

Back to Timeline
hasamba @hasamba@infosec.exchange · Jul 15, 2026
---------------- 🛠️ Clankerusecase — Threat-led Detection Library =================== Clankerusecase is a threat-led detection library providing detection rules across four platforms: Microsoft Defender KQL, Azure Sentinel KQL, Sigma, and Splunk SPL. The core value is reducing latency between threat intelligence publication and deployable detection content. 🔹 Two Content Tiers Generic use cases are rule files stored in use_cases/*.yml that activate when an article mentions a known trigger keyword. For example, an article referencing psexec fires the rule UC_LATERAL_PSXEC. These are broadly applicable but lack specificity to individual campaigns. They provide baseline coverage for well-known techniques and tools. AI-badged use cases represent a higher-fidelity tier. The pipeline feeds the source article to Claude, which generates bespoke detection logic targeting the exact campaign, threat actor, or malware family described. These rules are pinned to the specific IOCs and TTPs mentioned in the article. AI-badged use cases sort to the top of article cards and the matrix drawer to surface the highest-quality content first. 🔹 Cross-Verification Process AI-generated detections undergo a cross-verification step via web search against authoritative vendor advisories: Microsoft Threat Intelligence, Mandiant, CrowdStrike, MITRE ATT&CK, and abuse.ch. Each AI-badged rule includes "Cross-checked against:" references linking back to these verification sources. This adds a validation layer that pure LLM-generated detection rules typically lack. 🔹 Platform Coverage and Filtering Detection rules target four platforms, each with its own query language. The interface provides filter groups organized by Source, Content, Platform, Target, and Splunk category. On mobile viewports, the filter toolbar collapses behind a "Filters ▾" toggle to keep article cards above the fold. 🔹 Practical Considerations For detection engineers, the AI-badged use cases offer campaign-specific hunting logic without starting from scratch. The cross-check against vendor advisories provides some confidence, though this does not replace manual validation in production. The generic rules provide baseline coverage for known patterns, while AI rules address the gap for novel or recently reported threats. The quality of AI-generated rules depends on Claude's ability to accurately extract IOCs and TTPs from source articles. 🔹 detection_engineering #KQL #sigma #splunk #tool 🔗 Source: https://clankerusecase.com/
0
0
0
hasamba @hasamba@infosec.exchange · Jul 03, 2026

🛠️ Tool: SigmaLineage MCP

Sigma hits without context are noise. SigmaLineage MCP is a FastMCP server that wraps three capabilities into a single AI-callable interface, designed to solve the false-positive problem that plagues detection engineering.

What it does

  1. Sigma Hunt (run_sigma) — runs Chainsaw against an EVTX folder with the full SigmaHQ rule set.
  2. Process Lineage Tracing (run_sigma_lineage) — for every Sigma hit, automatically traces the parent→child execution tree up to 5+ generations, building a full kill-chain view.
  3. Rarity Baseline Engine (rare_events_baseline) — statistically surfaces anomalous process-to-port connections, suspicious user-log event combinations, and unusual URL lookups that don't fit the baseline.

The false positive problem

regsvr32.exe spawning a child process matches 40 Sigma rules and also matches every legitimate COM registration. wmic.exe executing a command could be lateral movement or your asset management tool. cmd.exe spawned by mmc.exe looks terrifying until you realize it is normal DCOM-based remote management. The alert alone tells you nothing. The parent chain tells you everything.

How lineage tracing works

SigmaLineage uses the Rust-backed evtx Python parser to build an in-memory process graph from Sysmon Event ID 1 (process creation) and Security Event ID 4688 in your EVTX corpus. It resolves ancestry using ProcessGuid strings for Sysmon events, and uses a PID + timestamp closest-fit algorithm for Security events that lack GUIDs. The result: for every Sigma hit, you get the full execution tree rendered in markdown.

Real example from EVTX-Attack-Samples — impacket wmiexec:

[WmiPrvSE.exe (PID: 836)] └─ [cmd.exe (PID: 2828)] (HIT) cmd.exe /Q /c whoami /all 1> \127.0.0.1\ADMIN$__1556656369.7 2>&1 └─ [whoami.exe (PID: 3328)] (HIT) whoami /all

One look and you know: cmd.exe spawned by WmiPrvSE.exe, writing output to the ADMIN$ share via a UNC path. Textbook WMI exec pattern. Not a false positive.

Compare to a surface-identical alert where lineage shows [services.exe] → [PSEXESVC.exe]. Same alert, different root cause (PsExec), instantly disambiguated.

The rarity engine solves anomaly discovery rather than false positive reduction. It statistically surfaces unusual process-to-port connections, suspicious user-log event combinations, and URL lookups without needing a predefined rule.

Plug into any MCP-compatible AI client (Cursor, Claude Desktop, Antigravity, OpenCode). Describe what you want to investigate in plain English, get structured analysis back.

Note: haven't tested personally.

🔹 SigmaLineage #tool #DetectionEngineering #Sigma #MCP

🔗 Source: https://mohitdabas.in/blog/sigmalineage-mcp-evtx-hunting-lineage-first-triage/

0
0
0

You've seen all posts