Detection rules › Sigma

Task Scheduler DLL Loaded By Application Located In Potentially Suspicious Location

Status
test
Severity
low
Log source
product windows, category image_load
Author
Swachchhanda Shrawan Poudel
Source
github.com/SigmaHQ/sigma

Detects the loading of the "taskschd.dll" module from a process that located in a potentially suspicious or uncommon directory. The loading of this DLL might indicate that the application have the capability to create a scheduled task via the "Schedule.Service" COM object. Investigation of the loading application and its behavior is required to determining if its malicious.

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 7Image loaded

Rule body yaml

title: Task Scheduler DLL Loaded By Application Located In Potentially Suspicious Location
id: 3b92a1d0-8d4b-4d28-a1b4-1e29d49a6a3e
status: test
description: |
    Detects the loading of the "taskschd.dll" module from a process that located in a potentially suspicious or uncommon directory.
    The loading of this DLL might indicate that the application have the capability to create a scheduled task via the "Schedule.Service" COM object.
    Investigation of the loading application and its behavior is required to determining if its malicious.
references:
    - https://www.logpoint.com/en/blog/shenanigans-of-scheduled-tasks/
    - https://x.com/Max_Mal_/status/1826179497084739829
author: Swachchhanda Shrawan Poudel
date: 2024-09-02
tags:
    - attack.persistence
    - attack.execution
    - attack.privilege-escalation
    - attack.t1053.005
    - detection.threat-hunting
logsource:
    category: image_load
    product: windows
detection:
    selection_dll:
        - ImageLoaded|endswith: '\taskschd.dll'
        - OriginalFileName: 'taskschd.dll'
    selection_paths:
        Image|contains:
            - ':\Temp\'
            - ':\Users\Public\'
            - ':\Windows\Temp\'
            - '\AppData\Local\Temp\'
            - '\Desktop\'
            - '\Downloads\'
    condition: all of selection_*
falsepositives:
    - Some installers might generate false positives, apply additional filters accordingly.
level: low

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_dll

selection_dll:
    - ImageLoaded|endswith: '\taskschd.dll'
    - OriginalFileName: 'taskschd.dll'

Stage 2: selection_paths

selection_paths:
    Image|contains:
        - ':\Temp\'
        - ':\Users\Public\'
        - ':\Windows\Temp\'
        - '\AppData\Local\Temp\'
        - '\Desktop\'
        - '\Downloads\'

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
Imagematch
  • :\Temp\ corpus 13 (sigma 13)
  • :\Users\Public\ corpus 15 (sigma 15)
  • :\Windows\Temp\ corpus 9 (sigma 9)
  • \AppData\Local\Temp\ corpus 11 (sigma 11)
  • \Desktop\ corpus 7 (sigma 7)
  • \Downloads\ corpus 10 (sigma 10)
ImageLoadedends_with
  • \taskschd.dll
OriginalFileNameeq
  • taskschd.dll