Suspicious Portable Executable Encoded in Powershell Script

Elastic Stack Serverless Security

Detects the presence of portable executables (PE) in a PowerShell script by looking for its encoded header. Attackers embed PEs into PowerShell scripts for injecting them into the memory, avoiding defenses by not writing to disk.

Rule type: query

Rule indices:

• winlogbeat-*
• logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Execution

Version: 2

Rule authors:

• Elastic

Rule license: Elastic License v2

event.category:process and
  powershell.file.script_block_text : (
    TVqQAAMAAAAEAAAA
  )

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Execution
  • ID: TA0002
  • Reference URL: https://attack.mitre.org/tactics/TA0002/

• Technique:

  • Name: Command and Scripting Interpreter
  • ID: T1059
  • Reference URL: https://attack.mitre.org/techniques/T1059/

• Sub-technique:

  • Name: PowerShell
  • ID: T1059.001
  • Reference URL: https://attack.mitre.org/techniques/T1059/001/