analyzing-powershell-script-block-logging

name	analyzing-powershell-script-block-logging
description	Parse Windows PowerShell Script Block Logs (Event ID 4104) from EVTX files to detect obfuscated commands, encoded payloads, and living-off-the-land techniques. Uses python-evtx to extract and reconstruct multi-block scripts, applies entropy analysis and pattern matching for Base64-encoded commands, Invoke-Expression abuse, download cradles, and AMSI bypass attempts. Use when working with analyzing powershell script block logging.
domain	cybersecurity
tags	["powershell","script-block-logging","event-id-4104","obfuscation-detection","windows-forensics","endpoint-security"]
subdomain	security-operations
version	1.0
author	oyi77
license	Apache-2.0
nist_csf	["DE.CM-01","RS.MA-01","GV.OV-01","DE.AE-02"]

Analyzing Powershell Script Block Logging

Overview

Cybersecurity skill for analyzing powershell script block logging. Follows industry best practices and security standards.

When to Use

Trigger phrases:

• "analyzing powershell script block logging"

• "Parse Windows PowerShell Script Block Logs (Event ID 4104) from EVTX files to de"

• When investigating security incidents that require analyzing powershell script block logging

• 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

When NOT to Use

• When you lack proper authorization for testing
• For production systems without change management
• When the task requires legal or compliance expertise beyond technical scope

Prerequisites

• Familiarity with security operations concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Workflow

# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}

1. Scope the Analysis — Define what powershell script block logging artifacts or data sources to examine and the investigation timeline.
2. Preserve Evidence — Create forensic copies of relevant data. Maintain chain of custody documentation.