Hide Schedule Task Via Index Value Tamper

Hunt Hypothesis

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 ab

Detection Rule

Sigma (Original)

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

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey endswith "\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Schedule\\TaskCache\\Tree*" and RegistryKey contains "Index") and RegistryValueData =~ "DWORD (0x00000000)"

KQL (Microsoft 365 Defender)

DeviceRegistryEvents
| where (RegistryKey endswith "\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Schedule\\TaskCache\\Tree*" and RegistryKey contains "Index") and RegistryValueData =~ "DWORD (0x00000000)"

Required Data Sources

False Positive Guidance

• Unlikely

MITRE ATT&CK Context

• Technique: T1685 — T1685

References

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