Detection rules › Sigma

Scheduled Task Creation Masquerading as System Processes

Status
experimental
Severity
high
Log source
product windows, category process_creation
Author
Swachchhanda Shrawan Poudel (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects the creation of scheduled tasks that involve system processes, which may indicate malicious actors masquerading as or abusing these processes to execute payloads or maintain persistence.

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Scheduled Task Creation Masquerading as System Processes
id: 9f8573c9-22b4-40e3-89c1-72bc2b8d49ab
status: experimental
description: Detects the creation of scheduled tasks that involve system processes, which may indicate malicious actors masquerading as or abusing these processes to execute payloads or maintain persistence.
references:
    - https://tria.ge/241015-l98snsyeje/behavioral2
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-02-05
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.stealth
    - attack.t1053.005
    - attack.t1036.004
    - attack.t1036.005
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\schtasks.exe'
        - OriginalFileName: 'schtasks.exe'
    selection_cli:
        CommandLine|contains|windash: ' /create '
        CommandLine|contains:
            - ' audiodg'
            - ' conhost'
            - ' dwm.exe'
            - ' explorer'
            - ' lsass'
            - ' lsm'
            - ' mmc'
            - ' msiexec'
            - ' regsvr32'
            - ' rundll32'
            - ' services'
            - ' spoolsv'
            - ' svchost'
            - ' taskeng'
            - ' taskhost'
            - ' wininit'
            - ' winlogon'
    condition: all of selection_*
falsepositives:
    - Legitimate system administration tasks scheduling trusted system processes.
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\schtasks.exe'
    - OriginalFileName: 'schtasks.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains|windash: ' /create '
    CommandLine|contains:
        - ' audiodg'
        - ' conhost'
        - ' dwm.exe'
        - ' explorer'
        - ' lsass'
        - ' lsm'
        - ' mmc'
        - ' msiexec'
        - ' regsvr32'
        - ' rundll32'
        - ' services'
        - ' spoolsv'
        - ' svchost'
        - ' taskeng'
        - ' taskhost'
        - ' wininit'
        - ' winlogon'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • /create transforms: windash corpus 15 (sigma 15)
  • audiodg
  • conhost
  • dwm.exe
  • explorer
  • lsass
  • lsm
  • mmc
  • msiexec corpus 2 (sigma 2)
  • regsvr32
  • rundll32 corpus 3 (sigma 2, splunk 1)
  • services
  • spoolsv
  • svchost
  • taskeng
  • taskhost
  • wininit
  • winlogon
Imageends_with
  • \schtasks.exe corpus 56 (sigma 56)
OriginalFileNameeq
  • schtasks.exe corpus 23 (sigma 18, splunk 4, elastic 1)