About

Imported from mukul975/anthropic-cybersecurity-skills (skills/hunting-for-anomalous-powershell-execution/SKILL.md). Install upstream with npx skills add mukul975/anthropic-cybersecurity-skills --skill hunting-for-anomalous-powershell-execution. Copyright stays with the author (Apache-2.0).

Hunting for Anomalous PowerShell Execution

Name: hunting-for-anomalous-powershell-execution
Author: mukul975

Overview

PowerShell Script Block Logging (Event ID 4104) records the full deobfuscated script text executed on a Windows endpoint, making it the primary data source for hunting malicious PowerShell. Combined with Module Logging (4103) and process creation events, analysts can detect encoded commands, AMSI bypass patterns, download cradles, credential theft tools, and fileless attack techniques even when the attacker uses obfuscation layers.

When to Use

When investigating security incidents that require hunting for anomalous powershell execution
When building detection rules or threat hunting queries for this domain
When SOC analysts need structured procedures for this analysis type
When validating security monitoring coverage for related attack techniques

Prerequisites

Windows Event Log exports (.evtx) from Microsoft-Windows-PowerShell/Operational
Python 3.8+ with python-evtx and lxml libraries
Script Block Logging enabled via Group Policy
Understanding of common PowerShell attack techniques

Steps

Parse EVTX files extracting Event 4104 script block text and metadata
Reassemble multi-part script blocks using ScriptBlock ID correlation
Scan script text for AMSI bypass indicators and obfuscation patterns
Detect encoded command execution and base64 payloads
Identify download cradles, credential dumping, and lateral movement commands
Score and prioritize findings by threat severity

Expected Output

{
  "total_events": 1247,
  "suspicious_events": 23,
  "amsi_bypass_attempts": 2,
  "encoded_commands": 8,
  "download_cradles": 5,
  "credential_access": 3
}

Use it

Copy one of these into your project. Installing also returns the manifest and these snippets.

yaml

targets:
  - https://api.opensmartroute.ai/api/v1/registry/mukul975-anthropic-cybersecurity-skills-hunting-for-anom-8f9140/manifest   # or paste the manifest below

Manifest

An Open Capability Manifest: the router reads it to know what this does, what it costs and when to pick it.

mukul975-anthropic-cybersecurity-skills-hunting-for-anom-8f9140.ocm.jsonjson

{
  "ocm": "1",
  "id": "mukul975-anthropic-cybersecurity-skills-hunting-for-anom-8f9140",
  "kind": "skill",
  "name": "hunting-for-anomalous-powershell-execution",
  "description": "Hunt for malicious PowerShell activity by analyzing Script Block Logging (Event 4104), Module Logging (Event 4103), and process creation events. The analyst parses Windows Event Log EVTX files to detect obfuscated commands, AMSI bypass attempts, encoded payloads, credential dumping keywords, and suspicious download cradles. Activates for requests involving PowerShell threat hunting, script block analysis, encoded command detection, or AMSI bypass identification.",
  "publisher": "mukul975",
  "version": "1.0.0",
  "capabilities": {
    "domains": [
      "general"
    ],
    "tags": [
      "skill-md",
      "powershell",
      "script-block-logging",
      "event-4104",
      "amsi",
      "threat-hunting",
      "evtx",
      "obfuscation",
      "skills-sh"
    ],
    "languages": [
      "en"
    ]
  },
  "quality_prior": 0.6,
  "examples": [
    "Hunt for malicious PowerShell activity by analyzing Script Block Logging (Event 4104), Module Logging (Event 4103), and process creation events. The analyst parses Windows Event Log EVTX files to detect obfuscated commands, AMSI bypass attempts, encoded payloads, credential dumping keywords, and suspicious download cradles. Activates for requests involving PowerShell threat hunting, script block analysis, encoded command detection, or AMSI bypass identification."
  ],
  "primary": false,
  "metadata": {
    "source": {
      "provider": "skills.sh",
      "repository": "https://github.com/mukul975/anthropic-cybersecurity-skills",
      "path": "skills/hunting-for-anomalous-powershell-execution/SKILL.md",
      "ref": "HEAD",
      "url": "https://github.com/mukul975/anthropic-cybersecurity-skills/blob/HEAD/skills/hunting-for-anomalous-powershell-execution/SKILL.md",
      "key": "mukul975/anthropic-cybersecurity-skills/skills/hunting-for-anomalous-powershell-execution/SKILL.md"
    },
    "license": "Apache-2.0"
  },
  "instructions": "# Hunting for Anomalous PowerShell Execution\n\n## Overview\n\nPowerShell Script Block Logging (Event ID 4104) records the full deobfuscated script text\nexecuted on a Windows endpoint, making it the primary data source for hunting malicious\nPowerShell. Combined with Module Logging (4103) and process creation events, analysts can\ndetect encoded commands, AMSI bypass patterns, download cradles, credential theft tools,\nand fileless attack techniques even when the attacker uses obfuscation layers.\n\n\n## When to Use\n\n- When investigating security incidents that require hunting for anomalous powershell e",
  "cost": {
    "context_tokens": 422
  }
}

Fetch it by URL: GET /api/v1/registry/mukul975-anthropic-cybersecurity-skills-hunting-for-anom-8f9140/manifest?version=1.0.0

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