Sigma rule: Suspicious Schtasks Schedule Types

Rule

Title

Suspicious Schtasks Schedule Types

Status

test

Level

high

Author

Nasreddine Bencherchali (Nextron Systems)

Date

2022-09-09

File

rules/windows/process_creation/proc_creation_win_schtasks_schedule_type.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects scheduled task creations or modification on a suspicious schedule type

Log source

product

windows

category

process_creation

Detection

selection_img:
    - Image|endswith: '\schtasks.exe'
    - OriginalFileName: 'schtasks.exe'
selection_time:
    CommandLine|contains:
        - ' ONLOGON '
        - ' ONSTART '
        - ' ONCE '
        - ' ONIDLE '
filter_privs:
    CommandLine|contains:
        - 'NT AUT' # This covers the usual NT AUTHORITY\SYSTEM
        - ' SYSTEM' # SYSTEM is a valid value for schtasks hence it gets it's own value with space
        - 'HIGHEST'
condition: all of selection_* and not 1 of filter_*

False positives (as the rule lists them)

• Legitimate processes that run at logon. Filter according to your environment

Tags

• attack.privilege-escalation
• attack.persistence
• attack.execution
• attack.t1053.005

MITRE ATT&CK ids this rule names

• T1053.005

Related rules

• 7a02e22e-b885-4404-b38b-1ddc7e65258a (similar)

References

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/schtasks-change
• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/schtasks-create
• http://blog.talosintelligence.com/2022/09/lazarus-three-rats.html

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_schtasks_schedule_type.yml