mukul975/analyzing-powershell-script-block-logging
skills/analyzing-powershell-script-block-logging/SKILL.md
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.
$ install --global
skillsauthnpx skillsauth add mukul975/anthropic-cybersecurity-skills analyzing-powershell-script-block-loggingInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
Security Scan Results
3 of 9 scanners reported clean
Some scanners were skipped, did not run, or reported a non-clean status. Review each row below.
3
Scanners Passed
9
Scanners in report
Clean
TrivyContainer and dependency vulnerability scanner
95%
Clean
SemgrepStatic code analysis for vulnerabilities
95%
Clean
mcp-scan (Snyk)Model Context Protocol security validation
95%
Skipped
Snyk (dep)Open source security scanning
50%
Skipped
Socket.devSupply chain security analysis
50%
Skipped
VirusTotalMulti-engine malware detection
50%
Skipped
CrowdStrikeAdvanced threat intelligence
50%
Skipped
OSV-ScannerOpen Source Vulnerability database check
50%
Skipped
OWASP Dep-Check
50%
Last scanned: Jun 2, 2026, 3:53 AM230.9s3 files scanned
SKILL.md
- name:
- analyzing-powershell-script-block-logging
- description:
- Parse Windows PowerShell Script Block Logs (Event ID 4104) from EVTX
- domain:
- cybersecurity
- subdomain:
- security-operations
- version:
- 1.0
- author:
- mahipal
- license:
- Apache-2.0
Analyzing PowerShell Script Block Logging
When to Use
- 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
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
Instructions
- Install dependencies:
pip install python-evtx lxml - Collect PowerShell Operational logs:
Microsoft-Windows-PowerShell%4Operational.evtx - Parse Event ID 4104 entries using python-evtx to extract ScriptBlockText, ScriptBlockId, and MessageNumber/MessageTotal for multi-part script reconstruction.
- Apply detection heuristics:
- Base64-encoded commands (
-EncodedCommand,FromBase64String) - Download cradles (
DownloadString,DownloadFile,Invoke-WebRequest,Net.WebClient) - AMSI bypass patterns (
AmsiUtils,amsiInitFailed) - Obfuscation indicators (high entropy, tick-mark insertion, string concatenation)
- Base64-encoded commands (
- Generate a report with reconstructed scripts, risk scores, and MITRE ATT&CK mappings.
python scripts/agent.py --evtx-file /path/to/PowerShell-Operational.evtx --output ps_analysis.json
Examples
Detect Encoded Command Execution
import base64
if "-encodedcommand" in script_text.lower():
encoded = script_text.split()[-1]
decoded = base64.b64decode(encoded).decode("utf-16-le")
Reconstruct Multi-Block Script
Scripts split across multiple 4104 events share a ScriptBlockId. Concatenate blocks ordered by MessageNumber to recover the full script.
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