Detection: Windows WinDBG Spawning AutoIt3

Description

The following analytic identifies instances of the WinDBG process spawning AutoIt3. This behavior is detected by monitoring endpoint telemetry for processes where 'windbg.exe' is the parent process and 'autoit3.exe' or similar is the child process. This activity is significant because AutoIt3 is frequently used by threat actors for scripting malicious automation, potentially indicating an ongoing attack. If confirmed malicious, this could allow attackers to automate tasks, execute arbitrary code, and further compromise the system, leading to data exfiltration or additional malware deployment.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes  where Processes.parent_process_name=windbg.exe  AND (Processes.process_name IN ("autoit3.exe", "autoit*.exe") OR Processes.original_file_name IN ("autoit3.exe", "autoit*.exe")) by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.original_file_name, Processes.process, Processes.process_id, Processes.parent_process_id 
 3| `drop_dm_object_name(Processes)` 
 4| `security_content_ctime(firstTime)` 
 5| `security_content_ctime(lastTime)` 
 6| eval matches_extension=if(match(process, "\\.(au3
 7|a3x
 8|exe
 9|aut
10|aup)$"), "Yes", "No") 
11| search matches_extension="Yes" 
12| `windows_windbg_spawning_autoit3_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'xmlwineventlog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

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

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

False positives will only be present if the WinDBG process legitimately spawns AutoIt3. Filter as needed.

Associated Analytic Story

• Compromised Windows Host

• DarkGate Malware

Risk Based Analytics (RBA)

References

• https://github.com/PaloAltoNetworks/Unit42-timely-threat-intel/blob/main/2023-10-25-IOCs-from-DarkGate-activity.txt

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: 5