Detection: Windows File Association Modification via Ftype

Description

This analytic detects the use of the ftype command to modify Windows file associations. Attackers can abuse this functionality to change how specific file types are handled, potentially redirecting legitimate file execution to malicious payloads. If confirmed malicious, this behavior may enable persistence, execution of unauthorized code, or evasion of security controls.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8Processes.process="*ftype*=*"
 9
10by Processes.process Processes.vendor_product Processes.user_id
11   Processes.process_hash Processes.parent_process_name
12   Processes.parent_process_exec Processes.action Processes.dest
13   Processes.process_current_directory Processes.process_path
14   Processes.process_integrity_level Processes.original_file_name
15   Processes.parent_process Processes.parent_process_path
16   Processes.parent_process_guid Processes.parent_process_id
17   Processes.process_guid Processes.process_id
18   Processes.user Processes.process_name
19
20
21| `drop_dm_object_name(Processes)`
22
23| `security_content_ctime(firstTime)`
24
25| `security_content_ctime(lastTime)`
26
27| `windows_file_association_modification_via_ftype_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'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

Legitimate users or administrators may run the ftype command to check or modify file associations. Filter alerts if used within authorized maintenance activities.

Associated Analytic Story

• Windows File Extension and Association Abuse

Risk Based Analytics (RBA)

Risk Message:

File Association Modification via Ftype using the command $process$ activity observed on $dest$.

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: 1