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Detection rules › Sigma

Uncommon One Time Only Scheduled Task At 00:00

Status
test
Severity
high
Log source
product windows, category process_creation
Author
pH-T (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects scheduled task creation events that include suspicious actions, and is run once at 00:00

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1053.005 Scheduled Task/Job: Scheduled Task
PersistenceT1053.005 Scheduled Task/Job: Scheduled Task
Privilege EscalationT1053.005 Scheduled Task/Job: Scheduled Task

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Uncommon One Time Only Scheduled Task At 00:00
id: 970823b7-273b-460a-8afc-3a6811998529
status: test
description: Detects scheduled task creation events that include suspicious actions, and is run once at 00:00
references:
    - https://www.trendmicro.com/vinfo/us/security/news/ransomware-spotlight/ransomware-spotlight-blackbyte
author: pH-T (Nextron Systems)
date: 2022-07-15
modified: 2023-02-03
tags:
    - attack.execution
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1053.005
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|contains: '\schtasks.exe'
        - OriginalFileName: 'schtasks.exe'
    selection_cli:
        CommandLine|contains:
            - 'wscript'
            - 'vbscript'
            - 'cscript'
            - 'wmic '
            - 'wmic.exe'
            - 'regsvr32.exe'
            - 'powershell'
            - '\AppData\'
    selection_time:
        CommandLine|contains|all:
            - 'once'
            - '00:00'
    condition: all of selection_*
falsepositives:
    - Software installation
level: high

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

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

Stage 2: selection_cli

selection_cli:
    CommandLine|contains:
        - 'wscript'
        - 'vbscript'
        - 'cscript'
        - 'wmic '
        - 'wmic.exe'
        - 'regsvr32.exe'
        - 'powershell'
        - '\AppData\'

Stage 3: selection_time

selection_time:
    CommandLine|contains|all:
        - 'once'
        - '00:00'

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
  • 00:00
  • \AppData\ corpus 8 (sigma 8)
  • cscript corpus 15 (sigma 15)
  • once
  • powershell corpus 25 (sigma 24, chronicle 1)
  • regsvr32.exe corpus 3 (sigma 3)
  • vbscript corpus 3 (sigma 2, splunk 1)
  • wmic corpus 2 (sigma 2)
  • wmic.exe corpus 2 (sigma 2)
  • wscript corpus 16 (sigma 16)
Imagematch
  • \schtasks.exe
OriginalFileNameeq
  • schtasks.exe corpus 23 (sigma 18, splunk 4, elastic 1)