Removal Of SD Value to Hide Schedule Task - Registry — Sigma Rule

Rule metadata and linked tags

Author: Sittikorn S. Source status: test; severity: medium. Source dates: 2022-04-15 / 2025-10-25.

{
  "product": "windows",
  "category": "registry_delete"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: f58cd85f440f172074572f9c6e6454d954210aa6c15b01c1f45ccda6fcb8f7e4

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Removal Of SD Value to Hide Schedule Task - Registry
id: acd74772-5f88-45c7-956b-6a7b36c294d2
related:
    - id: 526cc8bc-1cdc-48ad-8b26-f19bff969cec
      type: similar
status: test
description: Remove SD (Security Descriptor) value in \Schedule\TaskCache\Tree registry hive to hide schedule task. This technique is used by Tarrask malware
references:
    - https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/
author: Sittikorn S
date: 2022-04-15
modified: 2025-10-25
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: windows
    category: registry_delete
detection:
    selection:
        TargetObject|contains|all:
            - '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\'
            - 'SD'
    condition: selection
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/registry/registry_delete/registry_delete_schtasks_hide_task_via_sd_value_removal/info.yml

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.microsoft.com/security/blog/2022/04/12/tarrask-malware-uses-scheduled-tasks-for-defense-evasion/