Detection: Short Lived Scheduled Task

Updated Date: 2024-05-17 ID: 6fa31414-546e-11ec-adfa-acde48001122 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the creation and deletion of scheduled tasks within a short time frame (less than 30 seconds) using Windows Security EventCodes 4698 and 4699. This behavior is identified by analyzing Windows Security Event Logs and leveraging the Windows TA for parsing. Such activity is significant as it may indicate lateral movement or remote code execution attempts by adversaries. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or execution of malicious payloads, necessitating prompt investigation and response by security analysts.

Search

1 `wineventlog_security` EventCode=4698 OR EventCode=4699 
2| xmlkv Message 
3| transaction Task_Name  startswith=(EventCode=4698) endswith=(EventCode=4699) 
4| eval short_lived=case((duration<30),"TRUE") 
5| search  short_lived = TRUE 
6| rename ComputerName as dest
7| table _time, dest, Account_Name, Command, Task_Name, short_lived 
8| `short_lived_scheduled_task_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 4698	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
wineventlog_security	`eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security`
short_lived_scheduled_task_filter	`search *`

short_lived_scheduled_task_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1053.005	Scheduled Task	Execution

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

APT-C-36

APT29

APT3

APT32

APT33

APT37

APT38

APT39

APT41

BITTER

BRONZE BUTLER

Blue Mockingbird

Chimera

Cobalt Group

Confucius

Dragonfly

FIN10

FIN13

FIN6

FIN7

FIN8

Fox Kitten

GALLIUM

Gamaredon Group

HEXANE

Higaisa

Kimsuky

Lazarus Group

LuminousMoth

Machete

Magic Hound

Molerats

MuddyWater

Mustang Panda

Naikon

OilRig

Patchwork

Rancor

Silence

Stealth Falcon

TA2541

ToddyCat

Wizard Spider

menuPass

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, you need to be ingesting Windows Security Event Logs with 4698 EventCode enabled. The Windows TA is also required.

Known False Positives

Although uncommon, legitimate applications may create and delete a Scheduled Task within 30 seconds. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A windows scheduled task was created and deleted in 30 seconds on $dest$	81	90	90

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`WinEventLog:Security`	`WinEventLog`
Integration	✅ Passing	Dataset	`WinEventLog:Security`	`WinEventLog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 2