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

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-08-26 / 2025-10-25.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: dbc619c5361f577ba6f8e1fbea61cc472f6fe7df88aa1c911578ed2b6be92bbe

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 Index Value to Hide Schedule Task - Registry
id: 526cc8bc-1cdc-48ad-8b26-f19bff969cec
related:
    - id: acd74772-5f88-45c7-956b-6a7b36c294d2
      type: similar
    - id: 5b16df71-8615-4f7f-ac9b-6c43c0509e61
      type: similar
status: test
description: Detects when the "index" value of a scheduled task is removed or deleted from the registry. Which effectively hides it from any tooling such as "schtasks /query"
references:
    - https://blog.qualys.com/vulnerabilities-threat-research/2022/06/20/defending-against-scheduled-task-attacks-in-windows-environments
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-26
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\'
            - 'Index'
    condition: selection
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/registry/registry_delete/registry_delete_schtasks_hide_task_via_index_value_removal/info.yml

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://blog.qualys.com/vulnerabilities-threat-research/2022/06/20/defending-against-scheduled-task-attacks-in-windows-environments