Detection: Windows Indirect Command Execution Via Series Of Forfiles

Description

The following analytic detects excessive usage of the forfiles.exe process, which is often indicative of post-exploitation activities. The detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include process GUID, process name, and parent process. This activity is significant because forfiles.exe can be abused to execute commands on multiple files, a technique used by ransomware like Prestige. If confirmed malicious, this behavior could allow attackers to enumerate files, potentially leading to data exfiltration or further malicious actions.

Search

1
2| tstats `security_content_summariesonly` values(Processes.action) as action values(Processes.original_file_name) as original_file_name values(Processes.parent_process_exec) as parent_process_exec values(Processes.parent_process_guid) as parent_process_guid values(Processes.parent_process_id) as parent_process_id values(Processes.parent_process_path) as parent_process_path values(Processes.process) as process values(Processes.process_exec) as process_exec values(Processes.process_guid) as process_guid values(Processes.process_hash) as process_hash values(Processes.process_id) as process_id values(Processes.process_integrity_level) as process_integrity_level values(Processes.process_name) as process_name values(Processes.process_path) as process_path values(Processes.user) as user  values(Processes.user_id) as user_id values(Processes.vendor_product) as vendor_product count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "forfiles.exe" OR Processes.original_file_name = "forfiles.exe" by Processes.parent_process_name Processes.parent_process Processes.dest Processes.user _time span=1m 
3| where count >=20 
4| `drop_dm_object_name(Processes)` 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `windows_indirect_command_execution_via_series_of_forfiles_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

unknown

Associated Analytic Story

• Prestige Ransomware

• Windows Post-Exploitation

Risk Based Analytics (RBA)

Risk Message:

excessive forfiles process execution on $dest$

References

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/forfiles

• https://github.com/carlospolop/PEASS-ng/tree/master/winPEAS

• https://www.microsoft.com/en-us/security/blog/2022/10/14/new-prestige-ransomware-impacts-organizations-in-ukraine-and-poland/

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: 6