Detectionmediumtest

Schedule Task Creation From Env Variable Or Potentially Suspicious Path Via Schtasks.EXE

Detects Schtask creations that point to a suspicious folder or an environment variable often used by malware

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Florian Roth (Nextron Systems)Created Mon Feb 21Updated Tue Oct 0781325ce1-be01-4250-944f-b4789644556fwindows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection_1_create:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|windash: ' /create '
    selection_1_all_folders:
        CommandLine|contains:
            - ':\Perflogs'
            - ':\Users\All Users\'
            - ':\Users\Default\'
            - ':\Users\Public'
            - ':\Windows\Temp'
            - '\AppData\Local\'
            - '\AppData\Roaming\'
            - '%AppData%'
            - '%Public%'
    selection_2_parent:
        ParentCommandLine|endswith: '\svchost.exe -k netsvcs -p -s Schedule'
    selection_2_some_folders:
        CommandLine|contains:
            - ':\Perflogs'
            - ':\Windows\Temp'
            - '\Users\Public'
            - '%Public%'
    filter_optional_other:
        - ParentCommandLine|contains: 'unattended.ini'
        - CommandLine|contains: 'update_task.xml'
    filter_optional_team_viewer:
        CommandLine|contains: '/Create /TN TVInstallRestore /TR'
    filter_optional_avira_install:
        # Comment out this filter if you dont use AVIRA
        CommandLine|contains|all:
            - '/Create /Xml '
            - '\Temp\.CR.'
            - '\Avira_Security_Installation.xml'
    filter_optional_avira_other:
        # Comment out this filter if you dont use AVIRA
        CommandLine|contains|all:
            - '/Create /F /TN'
            - '/Xml '
            - '\Temp\'
            - 'Avira_'
        CommandLine|contains:
            - '.tmp\UpdateFallbackTask.xml'
            - '.tmp\WatchdogServiceControlManagerTimeout.xml'
            - '.tmp\SystrayAutostart.xml'
            - '.tmp\MaintenanceTask.xml'
    filter_optional_klite_codec:
        CommandLine|contains|all:
            - '\Temp\'
            - '/Create /TN "klcp_update" /XML '
            - '\klcp_update_task.xml'
    condition: ( all of selection_1_* or all of selection_2_* ) and not 1 of filter_optional_*