Scheduled Task Created by a Windows Script

Elastic Stack Serverless Security

A scheduled task was created by a Windows script via cscript.exe, wscript.exe or powershell.exe. This can be abused by an adversary to establish persistence.

Rule type: eql

Rule indices:

• winlogbeat-*
• logs-endpoint.events.registry-*
• logs-endpoint.events.library-*
• logs-windows.sysmon_operational-*
• endgame-*

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:

• Domain: Endpoint
• OS: Windows
• Use Case: Threat Detection
• Tactic: Persistence
• Tactic: Execution
• Data Source: Elastic Endgame
• Data Source: Elastic Defend
• Data Source: Sysmon
• Resources: Investigation Guide

Version: 209

Rule authors:

• Elastic

Rule license: Elastic License v2

Triage and analysis

Decode the base64 encoded Tasks Actions registry value to investigate the task’s configured action.

sequence by host.id with maxspan = 30s
  [any where host.os.type == "windows" and
    (event.category : ("library", "driver") or (event.category == "process" and event.action : "Image loaded*")) and
    (?dll.name : "taskschd.dll" or file.name : "taskschd.dll") and
    process.name : ("cscript.exe", "wscript.exe", "powershell.exe", "pwsh.exe", "powershell_ise.exe")]
  [registry where host.os.type == "windows" and event.type == "change" and registry.value : "Actions" and
    registry.path : (
      "HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Schedule\\TaskCache\\Tasks\\*\\Actions",
      "\\REGISTRY\\MACHINE\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Schedule\\TaskCache\\Tasks\\*\\Actions"
  )]

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Persistence
  • ID: TA0003
  • Reference URL: https://attack.mitre.org/tactics/TA0003/

• Technique:

  • Name: Scheduled Task/Job
  • ID: T1053
  • Reference URL: https://attack.mitre.org/techniques/T1053/

• Sub-technique:

  • Name: Scheduled Task
  • ID: T1053.005
  • Reference URL: https://attack.mitre.org/techniques/T1053/005/

• 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/

• Sub-technique:

  • Name: Visual Basic
  • ID: T1059.005
  • Reference URL: https://attack.mitre.org/techniques/T1059/005/