Detection: Windows Enable Win32 ScheduledJob via Registry

Description

The following analytic detects the creation of a new DWORD value named "EnableAt" in the registry path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\Configuration". This modification enables the use of the at.exe or wmi Win32_ScheduledJob commands to add scheduled tasks on a Windows endpoint. The detection leverages registry event data from the Endpoint datamodel. This activity is significant because it may indicate that an attacker is enabling the ability to schedule tasks, potentially to execute malicious code at specific times or intervals. If confirmed malicious, this could allow persistent code execution on the system.

Search

1
2| tstats `security_content_summariesonly` count values(Registry.registry_key_name) as registry_key_name values(Registry.registry_path) as registry_path min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path="*\\CurrentVersion\\Schedule\\Configuration*" Registry.registry_value_name=EnableAt  by Registry.dest, Registry.user, Registry.registry_value_name, Registry.registry_value_type 
3| `security_content_ctime(lastTime)` 
4| `security_content_ctime(firstTime)` 
5| `drop_dm_object_name(Registry)` 
6| `windows_enable_win32_scheduledjob_via_registry_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon EventID 12	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Sysmon EventID 13	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Annotations

Default Configuration

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

Implementation

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Registry node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

In some cases, an automated script or system may enable this setting continuously, leading to false positives. To avoid such situations, it is recommended to monitor the frequency and context of the registry modification and modify or filter the detection rules as needed. This can help to reduce the number of false positives and ensure that only genuine threats are identified. Additionally, it is important to investigate any detected instances of this modification and analyze them in the broader context of the system and network to determine if further action is necessary.

Associated Analytic Story

• Active Directory Lateral Movement

• Scheduled Tasks

Risk Based Analytics (RBA)

References

• https://securityonline.info/wmiexec-regout-get-outputdata-response-from-registry/

• https://learn.microsoft.com/en-us/windows/win32/cimwin32prov/win32-scheduledjob

Detection Testing

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: 3