Windows Scheduled Task Index Registry Tampering Hiding Tasks from Query Tools

title: Windows Scheduled Task Index Registry Tampering Hiding Tasks from Query Tools
id: 7620ccf8-5009-4bc2-b2be-dd8e9efcf331
related:
  - id: acd74772-5f88-45c7-956b-6a7b36c294d2
    type: similar
  - id: 526cc8bc-1cdc-48ad-8b26-f19bff969cec
    type: similar
  - id: 5b16df71-8615-4f7f-ac9b-6c43c0509e61
    type: derived
status: test
description: This rule identifies modifications where the DWORD value named "Index" under the scheduled task TaskCache Tree registry path is set to 0x00000000. Attackers can use this to impair defenses by hiding scheduled tasks from common management and query tooling. It relies on registry set telemetry that records the TargetObject path containing the TaskCache Tree location, along with the specific value and data type.
references:
  - https://blog.qualys.com/vulnerabilities-threat-research/2022/06/20/defending-against-scheduled-task-attacks-in-windows-environments
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_hide_scheduled_task_via_index_tamper.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2022-08-26
modified: 2023-08-17
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  category: registry_set
  product: windows
detection:
  selection:
    TargetObject|contains|all:
      - \SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\
      - Index
    Details: DWORD (0x00000000)
  condition: selection
falsepositives:
  - Unlikely
level: high
license: DRL-1.1