Hide Schedule Task Via Index Value Tamper — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-08-26 / 2023-08-17.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 5cdd07e59ded29ee8e2c017e615915c4575c236ad3b08621b52dcf0d05529e27

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: Hide Schedule Task Via Index Value Tamper
id: 5b16df71-8615-4f7f-ac9b-6c43c0509e61
related:
    - id: acd74772-5f88-45c7-956b-6a7b36c294d2
      type: similar
    - id: 526cc8bc-1cdc-48ad-8b26-f19bff969cec
      type: similar
status: test
description: |
  Detects when the "index" value of a scheduled task is modified from the registry
  Which effectively hides it from any tooling such as "schtasks /query" (Read the referenced link for more information about the effects of this technique)
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: 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

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

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