Sigma rule: Scheduled TaskCache Change by Uncommon Program

Rule

Title

Scheduled TaskCache Change by Uncommon Program

Status

test

Level

high

Author

Syed Hasan (@syedhasan009)

Date

2021-06-18

Modified

2025-10-22

File

rules/windows/registry/registry_set/registry_set_taskcache_entry.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Monitor the creation of a new key under 'TaskCache' when a new scheduled task is registered by a process that is not svchost.exe, which is suspicious

Log source

product

windows

category

registry_set

Detection

selection:
    TargetObject|contains: 'SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\'
filter_main_empty:
    Details: '(Empty)'
filter_main_null:
    Details: null
filter_main_other:
    TargetObject|contains:
        - 'Microsoft\Windows\UpdateOrchestrator'
        - 'Microsoft\Windows\SoftwareProtectionPlatform\SvcRestartTask\Index'
        - 'Microsoft\Windows\Flighting\OneSettings\RefreshCache\Index'
filter_main_mousocoreworker:
    Image|endswith: 'C:\Windows\System32\MoUsoCoreWorker.exe'
filter_main_services:
    Image|endswith: 'C:\Windows\System32\services.exe'
filter_main_tiworker:
    Image|startswith: 'C:\Windows\'
    Image|endswith: '\TiWorker.exe'
filter_main_svchost:
    Image: 'C:\WINDOWS\system32\svchost.exe'
filter_main_ngen:
    Image|startswith: 'C:\Windows\Microsoft.NET\Framework' # \Framework\ and \Framework64\
    Image|endswith: '\ngen.exe'
    TargetObject|contains:
        - '\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tasks\{B66B135D-DA06-4FC4-95F8-7458E1D10129}'
        - '\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\Microsoft\Windows\.NET Framework\.NET Framework NGEN'
filter_main_office:
    Image:
        - 'C:\Program Files\Microsoft Office\root\Integration\Integrator.exe'
        - 'C:\Program Files (x86)\Microsoft Office\root\Integration\Integrator.exe'
        - 'C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe'
        - 'C:\Program Files (x86)\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe'
filter_main_msiexec:
    Image: 'C:\Windows\System32\msiexec.exe'
filter_main_explorer:
    Image: 'C:\Windows\explorer.exe'
    TargetObject|contains: '\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\Microsoft\Windows\PLA\Server Manager Performance Monitor\'
filter_main_system:
    Image: 'System'
filter_main_runtimebroker:
    Image: 'C:\Windows\System32\RuntimeBroker.exe'
filter_optional_dropbox_updater:
    Image:
        - 'C:\Program Files (x86)\Dropbox\Update\DropboxUpdate.exe'
        - 'C:\Program Files\Dropbox\Update\DropboxUpdate.exe'
filter_optional_edge:
    Image|endswith:
        - 'C:\Program Files (x86)\Microsoft\EdgeUpdate\MicrosoftEdgeUpdate.exe'
        - 'C:\Program Files\Microsoft\EdgeUpdate\MicrosoftEdgeUpdate.exe'
filter_optional_onedrive:
    Image|endswith:
        - 'C:\Program Files (x86)\Microsoft OneDrive\OneDrive.exe'
        - 'C:\Program Files\Microsoft OneDrive\OneDrive.exe'
condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*

False positives (as the rule lists them)

• Unknown

Tags

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

MITRE ATT&CK ids this rule names

• T1053
• T1053.005

References

• https://thedfirreport.com/2021/03/29/sodinokibi-aka-revil-ransomware/
• https://labs.f-secure.com/blog/scheduled-task-tampering/

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/registry/registry_set/registry_set_taskcache_entry.yml