Potential PowerShell Obfuscated Script via High Entropy

Last updated 2 months ago on 2026-01-08

Created 2 months ago on 2026-01-08

About

Identifies PowerShell script blocks with high entropy and non-uniform character distributions. Attackers may obfuscate PowerShell scripts using encoding, encryption, or compression techniques to evade signature-based detections and hinder manual analysis by security analysts.

Tags

Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: Defense EvasionData Source: PowerShell LogsLanguage: kuery

Severity

low

Risk Score

MITRE ATT&CK™

Defense Evasion (TA0005)(external, opens in a new tab or window)

↳ Obfuscated Files or Information (T1027)(external, opens in a new tab or window)

↳ Deobfuscate/Decode Files or Information (T1140)(external, opens in a new tab or window)

Execution (TA0002)(external, opens in a new tab or window)

↳ Command and Scripting Interpreter (T1059)(external, opens in a new tab or window)

False Positive Examples

Legitimate large or encoded PowerShell scripts (automation frameworks, installers, or admin tooling) can exhibit high entropy or uneven character distributions.

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type: Query (Kibana Query Language)
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: logs-windows.powershell*
Related Integrations: windows(external, opens in a new tab or window)
Query

✄𐘗text code block:
✄𐘗event.category:process and host.os.type:windows and powershell.file.script_block_length > 1000 and
  powershell.file.script_block_entropy_bits >= 5.3 and powershell.file.script_block_surprisal_stdev > 0.7 and
  not file.directory: "C:\Program Files (x86)\Microsoft Intune Management Extension\Content\DetectionScripts"

Install detection rules in Elastic Security

Detect Potential PowerShell Obfuscated Script via High Entropy in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).