PowerShell Suspicious Payload Encoded and Compressededit

Identifies the use of .Net functionality for decompression and base64 decoding combined in PowerShell scripts, which Malware and security tools heavily use to deobfuscate payloads and load them directly in memory to bypass defenses.

Rule type: query

Rule indices:

  • winlogbeat-*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100


  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 1

Added (Elastic Stack release): 8.0.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positivesedit

Legitimate PowerShell Scripts which makes use of compression and encoding

Rule queryedit

event.category:process and powershell.file.script_block_text : (
(System.IO.Compression.DeflateStream or
System.IO.Compression.GzipStream or IO.Compression.DeflateStream or
IO.Compression.GzipStream) and FromBase64String )

Threat mappingedit