Windows Indirect Command Execution Via Series Of Forfiles

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Description

This analytic is developed to detect suspicious excessive usage of forfiles.exe process. This event was seen in post exploitation tool WINPEAS that was used by Ransomware Prestige. Forfiles command lets you run a command on or pass arguments to multiple files. This Windows OS built-in tool being abused to list all files in specific directory or drive.

• Type: Anomaly
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2022-11-30
• Author: Teoderick Contreras, Splunk
• ID: bfdaabe7-3db8-48c5-80c1-220f9b8f22be

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1202	Indirect Command Execution	Defense Evasion

Kill Chain Phase

• Exploitation

NIST

• DE.AE

CIS20

• CIS 10

CVE

Search

| tstats `security_content_summariesonly` values(Processes.process) as process values(Processes.process_guid) as process_guid  values(Processes.process_name) as process_name 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 
| where count >=20 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_indirect_command_execution_via_series_of_forfiles_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

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

Required fields

List of fields required to use this analytic.

• _time
• Processes.dest
• Processes.user
• Processes.parent_process_name
• Processes.parent_process
• Processes.original_file_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_path
• Processes.process_path
• Processes.parent_process_id

How To Implement

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

• Windows Post-Exploitation
• Prestige Ransomware

RBA

Risk Score	Impact	Confidence	Message
9.0	30	30	excessive forfiles process execution in $dest$

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

Reference

• 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/

Test Dataset

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

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